Dust-emitting regions today include both low-subtropical latitude arid regions such as dry lakes of the Bodélé Depression that supply diatomaceous-rich dust (West Africa; Washington et al. 2006; Chappell et al. 2008) and the Nile Delta plain, which fuels the dunes and loess of the Sinai and Negev (Muhs et al. 2013), as well as high-latitude proglacial and periglacial regions, such as the Copper River delta, which seasonally emits large volumes (60-160 ktons in 2006; Crusius et al. 2011) of glacially ground rock powder over hundreds of kilometers into the Gulf of Alaska (Fig. 11).


In all of these cases, the fines are inherent to, and emanate from, the (subaerially exposed and desiccated) depositional systems, rather than from eolian saltation.


The critical attributes of the Devono-Mississippian mudrocks of Oklahoma and the greater midcontinent include the: 1) fine grain size restricted to very fine silt to very fine sand with little to no clay (mineral or grain size), 2) blanket-like deposition over large regions, including far from paleocoastlines, 3) deposition in both sediment-starved basins as organic- rich and chert-rich mudstone, and in carbonate ramps as dispersed fines, 4) Downloaded from http://pubs.geoscienceworld.org/sepm/jsedres/article-pdf/92/12/1186/5763983/i1938-3681-92-12-1186.pdf by McGill University user ultimate sources in (primarily) the Appalachian orogen, and 5) enigmatic absence of proximal fluvio-deltaic feeder systems.

We propose that delivery of the siliciclastic material to epeiric seas by eolian transport best explains this confluence of attributes.


The predominantly arid and seasonally dry climate in the mostly subtropical latitudes of Devono-Mississippian Laurentia would have favored dust emission.

In this model, the Neoacadian Orogen clastic- wedge system (Catskill delta for the Devonian, and Price-Pocono-Borden delta and Mauch Chunk delta for the Mississippian) then provided the source of the material, which was derived from the orogenic highlands.

Notably, the Catskill delta system drained (at times) regions thought to have been glaciated during the latest Devonian (Brezinski et al. 2008, 2010; Ettensohn et al. 2020a, 2020b), and thus would have delivered a ready and voluminous source of Al-poor rock flour to the alluvial plain, analogous to the Copper River Delta today (Fig. 11).

Although no such glaciation is recorded outside of Gondwanaland for the Mississippian, the subaerial delta plains of the Price-Pocono-Borden-Grainger and Mauch Chunk deltas off the Appalachian Orogen would have supplied abundant silt, analogous to the Nile Delta today.

Mass-balance arguments suggest that only 1% (363 km 3 ) of the total quartz eroded from the Neoacadian orogen and delivered to the Mississippian fluvio-deltaic plains is needed to supply the volume of quartz in the Meramec and Sycamore systems (259 km 3 ) (Supplemental File 5).


The eolian-delivery model holds that austral winter winds along the Appalachian orogen front and Zonda-Foehn-Chinook-like leeward winds translating into easterlies (Figs. 10, 12) deflated these subaerial delta plains and lofted siliciclastic fines for ultimate deposition into the Laurentian epeiric seas and emergent land regions to the (paleo) north and west (Devonian), and (paleo) west (Mississippian) (Figs. 10, 12).

The strength of leeward winds can impose gusty conditions to generate intense dust storms, such as the Zonda winds off the Andes (Norte 2015; Puliafito et al. 2015; Isla et al. 2021), and Chinook winds that rework proglacial strata across the northern Great Plains today (Hugenholtz et al. 2007).

This model also explains the dearth of clay minerals (and thus Al), given the lack of intense chemical weathering expected in this arid climate region and-for the latest Devonian-the source in a proglacial delta system.


This model predicts the occurrence of similarly uniform fines distributed in coeval units across a large region of the Laurentian epeiric sea, as indeed occurs (Figs. 2, 3).

Additionally, it builds on several other examples of eolian-marine units posited for similarly enigmatic, fine-grained (and generally clay-poor) siliciclastic systems that lack fluvio-deltaic compo- nents, such as those of the Permian Delaware Mountain Group (Fischer and Sarnthein 1988), Phosphoria Formation (Carroll et al. 1998), various units of the Permo-Pennsylvanian (Soreghan 1992; Soreghan et al. 2008), and Lower Mississippian units of the Appalachian Basin (Cecil et al. 2018a).

Similarly, it builds on the eolian-dust model for the origin of chert in Paleozoic units of Laurentia proposed by Lowe (1976) and Cecil et al. ( 2018b).


The Woodford Shale consistently exhibits the finest modes of the study units and the highest silica content (Figs. 7, 8).

Its uniquely high silica content is commonly attributed to the influence of biogenic silica from nutrient-rich upwelling (Turner et al. 2016), but this explanation evades the root issue of an ultimate Si source.

Cecil et al. ( 2018b) posited that much Phanerozoic chert was likely sourced by eolian dust; this model seems viable for the Woodford Shale given the paleogeographic context of arid conditions across the midcontinent of Laurentia during the Late Devonian, conducive to the availability and transport of ultrafine siliceous dust.


We propose that the fine detrital modes reflect: 1) the distance to source and 2) the direction of surface wind circulation patterns, given the significant paleogeographic shifts from Late Devonian to Early-Middle Mississippian times (Figs. 10, 12).

During the Late Devonian, Oklahoma and the greater midcontinent seaway were situated west-northwest of the Catskill delta at 308 S. Prevailing winds off the leeward front of the Appalachian orogen would have transported eolian dust in a north and west-northwesterly direction, across the North American midcontinent to Oklahoma and beyond.

The emergent transcontinental arch may have provided temporary storage areas along this path.


Ultimately, the finest fraction accumulated in the Woodford Shale; by the Mississippian, shifts occurred in both the location of the primary source (now the Price-Pocono-Borden-Grainger, the Mauch Chunk deltas, and coastal clastic systems) and the paleolatitude (~158 northward).

By this time, the Price-Pocono-Borden-Grainger and Mauch Chunk deltas were east-southeast of Oklahoma, enabling prevailing easterlies to loft fines from these systems directly into the epeiric seas across the greater midcontinent.

With the northward drift of the Laurentian continent, Southern Hemisphere winter winds off the Appalachian orogen shifted to blow more directly toward the west and west-northwest (less circuitous than those of the Late Devonian).

This shift might explain the elevated grain sizes, higher volume of quartz, and more ''loess-like'' signature in the Meramecian samples of the Meramec and Sycamore (Fig. 8).

Additionally, orographic effects of the greater Appalachian orogen presumably further exacerbated the aridity across Laurentia, leading to enhanced eolian emissions.


Finally, widespread delivery of only minimally (chemically) weathered eolian fines to Devono-Mississippian epeiric seas may have had auxiliary effects on organic carbon in these systems.

The Mississippian (and Upper Devonian) of North America contain anomalously high organic carbon, with the Woodford Shale and correlatives considered world-class source rocks (Ulmishek and Klemme 1990; Kuuskraa 2011; Sonnenberg 2011).

We speculate that this remarkable organic richness might reflect eolian delivery of abundant nutrients (notably iron) to these distal epeiric seas, stimulating productivity and associated preservation of organic carbon, as has been observed in the Bering Sea (Koffman et al. 2021) and suggested in other deep-time, dust-sourced systems (e.g., Carroll et al. 1998; Gabbott et al. 2010; Sur et al. 2015; Abadi et al. 2020).


Siliciclastic silt and mudstone are common throughout Upper Devonian-Lower Mississippian epeiric-sea strata of Laurentia, but no proximal fluvial-deltaic feeder systems exist to explain transport of this material.

Mineralogical data indicate a clear detrital source.

Grain-size modes range from very fine silt to very fine sand, with minimal lateral variation in units across broad swaths of Oklahoma and the greater midcontinent region.

Geochemical signatures are Si-rich and Al-poor, reflective a dearth of clay minerals (particularly Woodford Shale and Sycamore systems).

Detrital-zircon geochronology indicates primary sources in the Appalachian orogen.


Paleogeographic reconstructions show that the midcontinent occupied the subtropical arid belt, in the orographic rain shadow of the growing Appalachian orogen.

Consequent aridity would have promoted dust emission from vast delta plains draining the Appalachian highlands.

Model simulations of surface wind circulations indicate that Southern Hemisphere winter months were conducive for eolian delivery of fine siliciclastic material toward the west and northwest, derived from Appalachian clastic wedges.

Alpine glaciation in these highlands during at least the latest Devonian produced large volumes of physically weathered fines.


Siliciclastic silt of the Upper Devonian Woodford Shale most likely experienced a circuitous eolian trajectory and greater transport distances, resulting in the predominance of very fine silt modes.

In contrast, Mississippian units were directly downwind of deltaic plains of the northern Appalachian system, resulting in generally coarser silt to very fine sand modes.


Coeval units located most distally contain abundant chert, consistent with sourcing from very fine silica dust.

Eolian transport of material that was minimally chemically weathered to Devono-Mississippian epeiric seas likely delivered essential nutrients that stimulated organic productivity in these commonly organic-rich units-a hypothesis that merits further investigation.


Supplemental material is available from the SEPM Data Archive: https:// www.sepm.org/supplemental-materials.


In a recently published paper, McGlannan et al. ( 2022) posit that the detrital silt component of Upper Devonian and Lower Mississippian shales of the North American midcontinent region is of eolian origin and provided essential nutrients that stimulated the organic productivity that is recorded by these shales.

Our initial concern with their study was the fact that McGlannan et al. ( 2022) studied a stratigraphic interval that spans approximately 20 million years (Late Devonian to Early Mississippian), and applied conclusions reached for the Mississippian part of the succession to the underlying Devonian black shales.

This is surprising because it is well known that a drastic sea-level fall occurred at the end of the Devonian and resulted in an unconformity over much of the North American craton [1][2].

As far as we understand from geologic literature, extrapolating the inferred sedimentary dynamics of one stratigraphic interval (Early Mississippian) across a sequence boundary to rocks that were deposited multiple millions of years earlier (Late Devonian) is neither recommended nor considered good practice.

The aim of this discussion is not to disqualify eolian systems in general as a potential source of fines in shale successions.

It is not implausible that there were times and places in the geologic past when they may have contributed to marine or lacustrine shale–mudstone successions.

We are, however, firmly convinced that in the case of the Late Devonian of North America, no compelling case can be made for a significant eolian clastic component to its widely distributed black-shale successions.

Whereas we disagree with the validity of the McGlannan et al. ( 2022) study at several levels, three principal lines of reasoning stand out to demonstrate that their conclusions are flawed and inapplicable to the Late Devonian black shales of North America.

First, petrographic examination of the rocks in question, collected from the same location as samples used by the authors (Woodford samples from McAlister Quarry), as well as samples from the Woodford of the Central Basin Platform (Permian Basin, Texas, samples courtesy of Kitty Milliken) does not support their assumptions about these rocks.

SEM analysis shows these samples to be strongly dominated by microcrystalline quartz (Fig. 1) and indicates that it is highly unlikely that the authors could have succeeded to extract detrital quartz grains from these rocks with the method described (McGlannan et al. 2022), much less using them for grain-size analysis.

The abundant early diagenetic silica cementation that fed on dissolution of radiolarian tests is so ubiquitous in these shales, generating silt- and even sand-size quartz particles [3][4][5] that upon crushing/processing it would inevitably have generated silt- and sand-size quartz particles (Fig. 2).

Petrographic constraints (Fig. 1), however, should readily disabuse a discerning observer from the notion that these particles are in any kind or form detrital in nature.

In our extensive experience with mudstone petrography, the detrital vs. authigenic nature of silt-size quartz grains cannot be determined (as the authors did) via inspection of “smear slides of residues” with a petrographic microscope.

To make that determination requires the resolution offered by scanning electron microscopes (SEM).

Figure 3 shows our Woodford samples from the perspective of scanned cathodoluminescence, illustrating the type and size range of detrital quartz.

The dominant reddish-orange colors of quartz grains suggest derivation from the same low-grade metamorphic source, the Acadian orogeny, presumed for Late Devonian black shales farther east [6].

The general abundance and size range of detrital quartz from the Woodford is in essence the same as that observed in Upper Devonian black shales of the Illinois Basin ca. 500 km to the east, and in the Williston Basin ca.

900 km to the north (Fig. 3), plausibly suggesting that all three locales received clastics from the Acadian orogen in the east [6].

The lacking differences in size range and source characteristics of detrital quartz (Fig. 3) between samples from Oklahoma and those of time-equivalent Devonian black shales from the Illinois and Williston basins (both far offshore the Acadian source region) supports strong dilution of clastics by early diagenetic silica in the case of the Woodford samples.

No principal difference is observed between these locales.

The randomly oriented phyllosilicate platelets (cardhouse fabric) observed in these rocks (Figs. 1, 4), shielded from compaction by early diagenetic silica cements (Figs. 1, 2), strongly suggests that the detrital component of these shales arrived via bedload transport of flocculated muds, and is quite similar to uncompacted fabrics seen in flume experiments that simulated accumulation of muds from bottom current transported floccules [7][8].

Settling of airborne dust through the water column should produce an entirely different fabric with largely bedding-aligned phyllosilicates [9].

Second, when examined in detail, Devonian organic-rich mudstone successions show rapid shifts of depocenters in response to basin dynamics (e.g., basement fault reactivation [10][11]) as well as accommodation change due to subsidence (tectonic) and sea-level fluctuations.

In the Late Devonian, regional unconformities (sequence boundaries) and their correlative conformities have been recognized and correlated across the United States by various authors [12][13][11].

Yet, these erosional contacts (and implicit hiatuses) are absent from Figure 2 of McGlannan et al. ( 2022), greatly oversimplifying the existing stratigraphic complexities.

Stratigraphic analysis shows that in the Appalachian Basin [14][11], the Illinois Basin [13], and in central Oklahoma [15], Devonian black shale successions invariably onlap onto structural highs (Cincinnati Arch, Nemaha Ridge).

Such distal responses to shoreline progradation and retrogradation imply lateral sediment supply (for example by wind-driven bottom-current systems) from a distal source and require shoreline-attached sediment dispersal systems.

Had eolian sediment dispersal indeed been the key control in the distal realm, stratal units should be expected to drape across positive elements, rather than terminate against them.

The most pervasive chert deposits associated with Late Devonian black shales occur in southern Laurentia, where a proximity to deep ocean waters and a combination of SE Tradewinds with the Ekman spiral provide ideal conditions for upwelling of nutrient-rich waters onto the flooded North American craton [16][17][18][19].

Whereas the influence of this nutrient source likely diminishes away from the cratonic edge [20][21], it is a highly plausible scenario for driving marine productivity in the Anadarko–Arkoma and Permian basins and the Woodford Shale sections sampled by McGlannan et al. ( 2022).

Third, due to the Devonian-age colonization of land masses by trees and other land plants, nutrient supply to shelf and epicontinental seas increased so dramatically [22][23] that eolian sourced nutrients, had they existed, would not have made any difference with regard to the available nutrient supply.

Also, as mentioned above, the very likely existence of upwelling of nutrient-rich deep-sea waters along the southern margin of the Late Devonian inland sea is a much more plausible nutrient source (rather than eolian input) for that part of the Late Devonian black-shale system.

Fundamentally, there is no need, nor any justification, to call on input of eolian clastics as a critical factor for the formation of any of the Late Devonian black-shale successions in North America.

Several studies of geochemical proxies and organic petrography have shown marine–terrestrial co-dependencies linking rapid expansion of land plants, enhanced continental weathering, terrestrial runoff, and nutrient supply from the Acadian borderlands to enhanced primary productivity in the Devonian inland sea [24][22][23][25][26][27].

Collectively, these studies evoke a mental image of coastal plains with thriving forests, unlikely to have facilitated widespread deflation and lofting of siliciclastic fines as postulated by McGlannan et al. ( 2022).

Furthermore, generating copious quantities of dust to fertilize the Devonian inland sea for several millions of years by way of deflation implies a commensurate concentration of sand and formation of eolian dunes [28].

Yet, in spite of a long history of research into Devonian nearshore and onshore deposits of the Appalachian Basin [29][30][31], no eolian deposits have ever been documented.

In summary, the confluence of petrographic constraints, stratigraphic relationships, and global controls thoroughly invalidates the premise of McGlannan et al. ( 2022).

The considered evidence shows a striking mismatch between well documented geologic realities and the “eolian supply” vision proposed by McGlannan et al. ( 2022).


We thank Wilson and Schieber for their discussion, as our paper in Current Ripples presented a new hypothesis, and we welcome tests of that hypothesis.

Current Ripples encourages “provocative papers on sedimentary geology” so we are happy to motivate future research toward advancing knowledge on the Devono-Mississippian of North America.

Through an integration of paleogeography, paleoclimate, grain size, detrital-zircon provenance, geochemistry, and surface-wind models, McGlannan et al. ( 2022) proposed that eolian transport supplied significant siliciclastic material to Devono-Mississippian marine strata of the North American midcontinent [1].

Wilson and Schieber (2024) begin their discussion with the statement that “...extrapolating the inferred sedimentary dynamics of one stratigraphic interval (Early Mississippian) across a sequence boundary to rocks that were deposited multiple millions of years earlier (Late Devonian) is neither recommended nor considered good practice.

” We find this odd, akin to arguing that, e.g., sediment dynamics of glacioeustasy in the Pleistocene cannot apply to glacioeustasy that operated in the Pennsylvanian.

Processes can apply across time, as long as the tenets of uniformity of process (uniformitarianism) are followed.

Wilson and Schieber (2024) then focus on three main arguments to challenge the validity of our hypothesis for the Late Devonian in particular.


Regarding the issue of an authigenic or detrital origin for the silica, we recognize that Schieber and his collaborators have extensive experience with mudstone petrography and petrology, are aware of and respect their work documenting diagenetic silica in mudstones, and indeed acknowledge in our paper the pervasive presence of diagenetic and biogenic silica in the Woodford Shale [1].

For example, Figure 5B in McGlannan et al. ( 2022) illustrates the rhythmic, thin, chert-like beds in the Woodford Shale.

Wilson and Schieber note that they have studied samples from the same sites we studied and found diagenetic silica.

We do not doubt this.

Owing to the common presence of diagenetic silica, we preferentially avoided silica-rich facies and predominantly sampled laminated shale facies.

Wilson and Schieber (2024) suggest that we generated sand- and silt-size particles “upon crushing–processing” but, as we detailed in our paper, “Samples were gently crushed with a ceramic mortar and pestle to pea-size gravel to accelerate chemical reactions, then rinsed with distilled water and sieved at 250 lm to remove any fines generated during crushing” that might be erroneously incorporated in the grain-size analyses.

Of 19 Woodford Shale samples, 12 were selected for particle-size measurement after smear-slide analysis to verify disaggregation and presence of a preponderance of detrital material (Supplemental File 3 and Fig. 6A in McGlannan et al. 2022), which included not only quartz, but minor feldspar and even (rare) accessory minerals such as zircon.

We acknowledge that, despite our efforts to minimize the inclusion of diagenetic silica, some microcrystallized silica may have remained, which would have skewed particle-size results to finer modes.

Additionally, as discussed in our paper, eolian delivery of silica-rich dust likely provided a significant source of Si for biogenic and diagenetic silica in these Devono-Mississippian units—an interpretation that builds on previous work by others, such as Banks (1970), Cecil (2015), and Cecil et al. ( 2018) [2][3][4].

Wilson and Schieber (2024) then address stratigraphic relationships, implying that we believe the Woodford (and correlative black shales) should exhibit a draping geometry owing to hemipelagic settling, but we do not, in any way, dispute a component of bottom-current transport for the redistribution of detrital material in the Woodford Shale or any of its correlative formations.

We absolutely acknowledge the action of submarine redeposition and redistribution.


We mention several times throughout the paper that these sediments were ultimately deposited in the marine environment, but we hypothesize eolian delivery of the material to the marine system.

Once eolian dust hits the surface waters, it is subject to marine processes, especially if accumulation occurs on submarine slopes.

Analogous systems wherein submarine mass flows redistributed eolian-transported fines include the sandstones and siltstones of the Permian Delaware Mountain Group, for example (Fischer and Sarnthein 1988) [5].

We do not doubt the existence of stratigraphic complexities related to basin dynamics and sea-level fluctuations.

Stratigraphic complexities in the Woodford Shale related to relative changes in base level are certainly present in Oklahoma, but the comparison of these complexities to those in the Appalachian foreland basin and the intracratonic Illinois and Michigan basins requires much further stratigraphic study.

During the Late Devonian the Anadarko basin was essentially a wide passive margin facing southward into the Rheic Sea. Although there appears to be an intra-Woodford unconformity at the Devonian–Carboniferous boundary, the continuity in conodont and pollen biozones at the I-35 South outcrop in Oklahoma (Over 1990, 1992; Kondas et al. 2018) and conodont zones at the Wapanucka (Over 1990), and Hass G (Boardman and Puckette 2006; Haywa-Branch and Barrick 1990; Over and Barrick 1990) locations demonstrate that the Upper Woodford unconformity is of a lower magnitude than certain regions in the up-dip interior Illinois basin (Over et al. 2019; Over 2021; Fig. 6 in Lazar and Schieber 2022) [6][7][8][9][10][11][12][13][14].

Yet, the sediments are similar; therefore eolian delivery provides a viable means for transporting sediments beyond the Appalachian system.


In their third major point, Wilson and Schieber (2024) take issue with the hypothesis of eolian nutrient fertilization.

Regarding nutrients supplied to Devonian epeiric seas, we accept the possibility of eutrophication from the expansion of terrestrial land plants, and deep basin upwelling, in addition to eolian dust fertilization.

We did not exclude any mechanism by which nutrients might have reached the marine system.

Rather, we merely suggested dust as a possible carrier of iron, in light of the eolian hypothesis.

We are raising questions and proposing hypotheses to consider.

We do not know how significant dust may (or may not) have been in delivering nutrients (bioavailable iron) across Laurentian epeiric seas during the Late Devonian.

Mechanisms of nutrient delivery are not mutually exclusive.

In other words, sometimes the answer isn’t either/or, but both, or all the above.


Finally, we disagree with Wilson and Schieber’s (2024) argument on the requirement for “a commensurate concentration of sand and formation of eolian dunes” to generate “copious quantities of dust.” As addressed in our paper, whilst much controversy surrounds the claim that sand dunes and eolian processes produce significant dust deposits, both empirical and experimental studies raise questions about the efficacy of sand saltation in producing silt, and this remains a contentious claim.

For example, although sand saltation has been suggested for small loess accumulations such as the Negev in Israel (Crouvi et al. 2008), relatively minimal eolian silt (loess) occurs in the peri-Saharan region, for example (Smalley 1995)—where one might expect large volumes given the vast sand seas [15][16].

Furthermore, recent experimental studies demonstrate the inefficiency of eolian saltation of sand for silt production (Swet et al. 2019, 2020; Adams and Soreghan 2020) [17][18][19].

Consider that the dustiest source on the planet today, the Bodélé Depression, is not sourced by dunes, but by the desiccated-lake deposits of paleolake Megachad (Warren et al. 2007) [20].

Similarly, dust off the Copper River Delta today is sourced by the deflation of glacially generated fines across (dried) floodplains, not sand dunes (Crusius et al. 2011) [21].

We again thank Wilson and Schieber for the opportunity for additional discussion, and for highlighting the need for further petrographic and SEM studies of the Woodford Shale focused specifically on the detrital component.

It is likely we will continue to agree to disagree on several points; even so, we look forward to further testing and revision of our hypothesis that eolian-transported detrital silt and dust contributed to the Woodford Shale, and many of its correlatives.


Since the 1960s, considerable effort has been made to develop a valid, reproducible and standardised orthodontic index.

Occlusal indices such as the Index of Orthodontic Treatment Need (IOTN) [1], and the Dental Aesthetics Index (DAI) [2] have been developed to rank malocclusion according to the level of treatment need.

Occlusal indices can be defined as methods for determining the level of treatment need or the amount of deviation from normal occlusion and can be used for the evaluation of individual patients and populations [3].

Occlusal indices such as the DAI [2] and the IOTN [1] are used to determine the need or priority for orthodontic treatment in epidemiological surveys.


The Dental Aesthetic Index (DAI), adopted by the World Health Organization, evaluates 10 occlusal characteristics: overjet, negative overjet, tooth loss, diastema, anterior open bite, anterior crowding, anterior diastema, width of the anterior irregularities (mandible and maxilla) and antero-posterior spring relationship [2].

The DAI has four stages of malocclusion severity: a score lower than or equal to 25 (no or slight treatment need), a score between 26 and 30 (elective treatment), a score between 31 and 35 (treatment highly desirable) and a score greater than 36 (treatment mandatory) [4].

The IOTN records the need for treatment based on two components: the Dental Health Component (DHC) and the aesthetic component (AC).

The DHC-IOTN consists of a hierarchical scale with five levels: level 1 represents little or no need for treatment and level 5 represents a great need for treatment.

It evaluates the malocclusion by means of five characteristics: tooth loss, overjet, crossbite, displacement of the contact point, and overbite [1].


Thus, despite having a similar goal, the DAI and the DHC-IOTN exhibit differences that determine their ability to predict malocclusion and the need for orthodontic treatment.

Moreover, the IOTN has been described as an index for easy use [1].

In Brazil, the DAI has been used in national epidemiological surveys organised by the Ministry of Health.

Other epidemiological surveys, using DAI or IOTN, were carried out in Brazil [5], Spain [6], India [7] and United States [8].

This study aimed to assess the validity and reproducibility of the DAI and the DHC-IOTN in the identification of orthodontic treatment needs.


This study was carried out between July and October 2009.

The study involved the assessment of a sample of 131 pairs of dental casts selected randomly from the archive of the Specialization Course in Orthodontics at the Faculty of Dentistry, Universidade Federal de Minas Gerais, Brazil.

This archive 3279 contains 198 models of oral cavities of all orthodontic patients from Universidade Federal de Minas Gerais.

Models in inadequate conditions (with fractures in casts) and models of patients who had received previous orthodontic treatment were not included.

The age of participants whose models were included in this study ranged from 12 to 15 years, an age group recommended in studies of occlusal indices by several authors [2,4].

The patients, whose models were evaluated, were at early permanent dentition.


The sample size calculation was performed by considering the 54.3% prevalence of orthodontic treatment need, as measured by the DAI [9], with a confidence interval of 95% and 5% of level of precision.

Approval was obtained from the Ethics Committee in Research of Universidade Federal de Minas Gerais (No 0369.0.203.000-09).


First, to assess reproducibility, 13 models (10% of the total sample set) were examined on two occasions, with an interval of 30 days between examinations, using the two indices proposed in the study.

The reproducibility analysis was carried out before the validation analysis.


After the reproducibility assessment, the 131 study models were examined by the researcher, an expert in orthodontics, to assess the ability of both indices to identify orthodontic treatment need.

The DAI [2,4] and the DHC-IOTN [1] values were classified according to the specific criteria of each index studied.

The recommendations were used to measure the DHC-IOTN in the models [10].

The aesthetic component of the IOTN was not assessed, as it presents poor association with the clinical condition when used in models [11].

The instruments used were those recommended for each index, namely the periodontal probe for the DAI and the proper ruler for the DHC-IOTN.


The gold standard of orthodontic treatment need was determined by three professors who are experts in the area of orthodontics with at least 10 years of clinical experience [12].

They examined the 131 study models separately.

Each model was coded as "no need for orthodontic treatment", "elective orthodontic treatment" or "orthodontic treatment required" based on the clinical evaluation of each one.

Where there was disagreement in the assessment of the models, there was a discussion among the researchers to reach a consensus [12-14].


The DAI scores and degrees of treatment need as determined by the DHC-IOTN were regrouped in a dichotomous manner as follows: "without treatment needs" and "in need of treatment".

The DAI scores were dichotomised as "no need for treatment" (DAI ≤ 25) and "in need of treatment" (DAI > 25).

The DHC-IOTN is subdivided into three stages of severity according to the need for treatment.

Grade 1 (none) and 2 (little) were considered as not requiring treatment, while Grades 3 (moderate need), 4 (great need) and 5 (very great need) were considered as in need of treatment [1] In the same way, the gold standard evaluation was dichotomised as follows: "without treatment needs" and "in need of treatment".

The latter category included "elective orthodontic treatment" and "orthodontic treatment required".

The time needed to evaluate the indices was measured by a digital stopwatch by the same researcher who evaluated the models.


To assess the reproducibility of the original DAI and DHC-IOTN values, the average estimate of the intraclass correlation coefficient for agreement (95% IC) was calculated.

The Cohen Kappa coefficient (95% IC) and the Prevalence-adjusted bias-adjusted Kappa (PABAK) [15] were calculated to measure agreement between the dichotomised DAI and DHC-IOTN.

An evaluation of the normality of the variable "time" was conducted using the Kolmogorov-Smirnov test.

The comparison between time needed to evaluate the indices was done by the Wilcoxon test.

The significance level was set at 5% for all analyses.

The validation of the indices was done by calculating sensitivity, specificity, positive predictive value, negative predictive value and accuracy (area under the receiving-operating characteristic curve [ROC curve]).

An optimum cutoff point for each of the indexes was determined by plotting ROC curves.


The mean (±Standard Deviation) and median DAI values obtained were 35.4 (±10.9) and 33.0, respectively.

The minimum and maximum values were 19 and 98.

For the ordinal DHC-IOTN, the minimum and maximum values ranged between 1 and 5.

The orthodontic treatment need according to the DAI and DHC-IOTN evaluation made by the examiner were presented on Table 1.

The intra-rater reliability assessment resulted in an intraclass correlation coefficient of 0.89 for the DAI (95% IC = 0.64 to 1.0) and 0.87 for the DHC (95% CI = 0.56 to 0.96).

Table 2 shows the comparison between the two indices, the Cohen Kappa and PABAK coefficients.


The time spent (in seconds) to assess the DAI and the DHC-IOTN were presented on Table 3.

These variables were not normally distributed (Kolmogorov-Smirnov test, P < 0.05).

The time spent to assess the DHC-IOTN was statistically lower than that for the DAI (Wilcoxon test, P < 0.001).


When comparing the two indices with the gold standard (Table 4), less agreement on the overall diagnosis of models examined for treatment needs was observed (47% according to the DAI and 52% according to the DHC-IOTN), with a significant percentage of false positives both for the DAI (41%) and the DHC-IOTN (39%).

The accuracy of the indices, as reflected by the ROC curve, was also presented (Figure 1).

In the analysis of the validity of the indices (Table 5), both had great sensitivity and very low specificity, indicating a good ability to identify orthodontic treatment need in patients.

However, the positive predictive value (PPV) for both indices was low, reducing the certainty of the sensitivity.

Otherwise, the specificity is low but the negative predictive value is high.

The new cutoff points (DAI=31, and DHC=3), have changed the properties of indexes.


Indices could be considered useful for epidemiological and public health applications when they are reliable and valid.

Considering the results presented, the DAI and DHC-IOTN could be considered reliable and validity.


For the sample size calculation of our study we could use the frequency of orthodontic treatment need as measured by the DHC-IOTN or by the DAI.

Considering that orthodontic treatment need based on research with orthodontic study models was about 15.0% [16], we opted for the frequency of orthodontic treatment need determined by the DAI [9] because it ensured a larger sample set.

The literature have pointed out that it is possible and correct to use dental models in order to validate orthodontic indices [14,17].

Besides, the reliability and agreement between the information obtained clinically and from diagnostic models are high [11].

For these reasons and due to feasibility, we carried out the study using dental models.


High intra-examiner agreement existed between the original DAI and DHC-IOTN values.

The examiner was trained and calibrated in the use of the indices before the evaluation sessions, which confirms the need for those steps before an epidemiological survey.

This step contributed to the good results.


However, the examiner was a specialist in orthodontics, and epidemiological surveys are normally conducted by general dentists, which may point to the need for more previous training.

It might be necessary to evaluate the reliability and validity of occlusal indices between general dentists as well.

It is important that the indices have a high degree of reproducibility to be useful as a research tool.


Despite the lower ICC DHC-IOTN as compared to the DAI value, the confidence intervals are coincident, showing that the reproducibility of both is similar [1,11,12,17,18].

Despite the high percentage of agreement between both indices, the Cohen Kappa could be considered fair.


However, considering that the agreement between positive classification (orthodontic treatment need) for DAI and DCH-IOTN was high, Cohen Kappa was artificially low.

So, the Prevalence-adjusted bias-adjusted Kappa was calculated and it was considered substantial.

So, the DAI and DHC-IOTN measure orthodontic treatment needs in the same way [15].


Most cases showed the need for treatment.

This high prevalence is similar to the results of other studies because these validation studies are usually conducted in orthodontics settings, where study models are provided and where most cases for treatment are, due to the need for diagnosis [14,16,17,19].


In validity studies of the occlusal indices, an important factor is the definition of the gold standard.

The literature has considered a panel of orthodontists to be the gold standard.

This assessment, as defined by several authors [20,21], has been considered the gold standard of the orthodontic treatment needs.

However, there are at least two ways to define this panel: using the Likert scale [17] or by consensus [12].

The number of orthodontists in this type of panel has varied from two [12] to eighteen [21].


Our study had a consensus panel of three orthodontists, similar to that of Freer and Freer [12].

It seems necessary to standardise the construction of these panels worldwide to better define the need for orthodontic treatment.

It is not easy to infer the effect on the validity statistics of the DHC-IOTN and DAI if the number of specialists participating in the panel were changed.

In Brazil, the post-graduate Orthodontic programs vary in content and length of study which may potentially increase the discordance among specialists' determinations of treatment need.


The comparison with the gold standard has shown an impressive amount of false positives.

This is a worrying finding because about 50% of the cases were determined to need treatment based on both indices which a committee of experts in orthodontics had not noticed.

In this case, an epidemiological survey using these indices may overestimate the need for treatment in a population.

The modification in the cutoff points has decreased the proportion of false-positive and has increased the proportion of false-negative results in both indices.

The overall concordance has slightly increased.


In the validity assessment, the DHC-IOTN showed a sensitivity of 100% and DAI, 91%, i.e., the probability of the assessment performed correctly indicate the orthodontic treatment needs is great.

Both showed low values of specificity (DAI = 14% and DHC-IOTN = 19%).


In epidemiological surveys, sensitive tests are useful because they prevent people with a problem from being disregarded.

Depending on the problem, this can be a complicating factor in finding a solution.

Moreover, specific tests are also desirable because they contribute to cost reduction both in the need for subsequent examinations and in the treatment that will be provided.

The low specificity is related to a high degree of false positives, which affects the good sensitivity.

Thus, it would be desirable to have a balance of these two characteristics, but that did not occur with the DAI and DHC-IOTN indices.

Thus, it is necessary to develop an occlusal index that evaluates orthodontic treatment needs more accurately.

This development process is not easy and could be done with participation of experts in orthodontics, public health, epidemiology, statistic from all over the world.


The positive predictive value (PPV) for the two indices is low (28 for the DAI and 31 for the DHC-IOTN).

Whereas PPV increases with increasing prevalence, this is another deficiency in the validity of these indices.

The modification in cutoff points increased the PPV and specificity for the two indices.

However, the others properties (sensibility and negative predictive value) have decreased.

The deficiencies observed in the characteristics analysed concerning the validity of a test resulted in the accuracy values (DAI = 0.61 and DHC-IOTN = 0.67).


Studies with American [2] or English [1] orthodontists showed better accuracy levels.

However, in another study [14], the accuracy of the IOTN was very similar to our results.

The validity of an index can depend on the origin of the orthodontic experts who determine as the gold standard [14].


As discussed previously, an expert's opinion is currently regarded as the best determinant of the treatment need because of the difficulty in using occlusal indices to identify and quantify the objective signs of malocclusion and orthodontic treatment needs [10,21,22].

Therefore, the aggregate decision of orthodontic specialists is generally regarded as the gold standard against which any occlusal index should be validated [20,21].

The different methods of obtaining the gold standard in the validation studies could also explain the different accuracy results for the occlusal indices [12,21].


The time spent for the assessment of the DAI was longer than for the DHC-IOTN.

This is probably because only the worst occlusal feature is recorded by the DHC-IOTN [3].

In other words, the identification is made through a hierarchical scale of occlusal anomalies, whereas several occlusal features of space and the teething are recorded to obtain the final DAI score.

Reducing the time needed for index application is always important, especially in population studies [22].

Despite not assessing the aesthetic component of the IOTN once we evaluated dental models [11], the inclusion of this component would increase the time spent in evaluation.

A disadvantage of DHC-IOTN use is that the proposed ruler for the index is not easily found, whereas the DAI is an index whose instrument for measurement (periodontal probe) is easily accessible.


It is necessary to point out some limitations of this study.

The study was conducted with a small group of Brazilian orthodontists, and the sample, although probabilistic, is representative of a single orthodontics service in Brazil.

Other studies should be conducted to assess the validity and reproducibility of the DAI and IOTN among Brazilian orthodontists.

Although there is little option for orthodontic treatment in public health in Brazil, the choice of a reliable and valid instrument is essential for a correct epidemiological diagnosis.

Additionally, the incorporation of subjective evaluation in the epidemiological diagnosis of orthodontic treatment need is absolutely relevant [23,24].

The studied indices are epidemiological tools that aim to assess the degree of treatment need and not make diagnoses or aid in orthodontic planning.

The epidemiological indices usually underestimate the studied disease, which has not occurred in this case.

Further research in this area is important so that the epidemiological findings can be utilised as a reliable tool for planning and evaluation of public health actions.


The DHC and the DAI are reproducible and have reasonable accuracy.

The biggest problem presented is the high false positive rate compared to the gold standard.

The DHC has the advantage of being an index of rapid implementation.

The time spent assessing the DAI is greater than that spent assessing the DHC.


In regard to the article entitled “The Dental Aesthetic Index and Dental Health Component of the Index of Orthodontic Treatment Need as Tools in Epidemiological Studies” by Cardoso et al. [ 1] which checks the validity and agreement of two scales for orthodontic treatment need, we would like to draw your attention to a number of discrepancies in the design and methodology which have affected the results:


The authors have chosen a sample where the prevalence of orthodontic treatment need (according to the gold standard) is 91%.

Unfortunately, this is not a true representation of the orthodontic treatment need of the population.

In a literature review of studies published between 1951 and 2000 (in total 25 studies), covering orthodontic treatment needs in different ethnic groups, Thilander et al. [ 2] reported only 10 (40%) studies reporting orthodontic treatment need above 75% while only one (4%) study (Law et al., [ 3]) in a Chinese population reported the prevalence of orthodontic treatment need above 90%, as reported by Cardoso et al. It is unfortunate that Cardoso et al. have chosen dental casts from the archive of Specialization Course in Orthodontics of a dental school—which indicates that these casts were prepared for the subjects who had undergone orthodontic treatment.

This gives rise to one question i.e. whether the 9% of casts shown to be not requiring orthodontic treatment were actually of subjects who did not require orthodontic treatment?

In our opinion, for such important research in which two scales were being evaluated and the study was carried out with the help of dental casts (post-hoc design), the valid option would have been to include a higher number of otherwise normal casts (as per the gold standard), as this was not a prospective study and could have been easily controlled.

Otherwise, the study should have been carried out as a random evaluation in a sample drawn from the population.


The authors have shown the diagnostic accuracy of the two scales to be 61% and 67%, respectively.

Now here we would like to provide a random simulation wherein the diagnostic accuracy will lead to an even higher result without using any scale in such a high prevalence situation.

Suppose, using random criteria we propose all the 100% subjects to be requiring the treatment (Table 1).


Table 1.

Diagnostic Efficacy in high prevalence cases.


Random criteria


Yes
No
Total


Gold standard


Yes
91
0
91


No
9
0
9


Total


100
0
100


Using these random criteria (which in fact are no criteria), owing to high prevalence the criteria has a diagnostic accuracy of 91%, sensitivity of 100% and specificity of 0%.

This simulation shows that in case of a high prevalence, the accuracy of a model can be a wrong inference.

The poor specificity as observed by Cardoso et al. in this article indicates that despite the use of proposed scales, the entire population has to be screened again by panel approach (gold standard) which shows that the time spent on administration of scales is of no use at all, rather it increases the overall time for treatment need assessment without adding any utility.

Secondly, in such a situation, DHC cut-off 2 seems to be a better choice as at least it does have a 100% sensitivity, which means that the panel has not to go beyond the screened subjects.


In regard to reproducibility, we are amazed to see that the authors have used test-retest validation for only 10% of the samples, which merely turns out to be 13 models.

It is difficult to assume that with the primary aim of the study being stated as “to assess the validity and reproducibility of the DAI and the DHC-IOTN in the identification of orthodontic treatment needs”, the reproducibility has been checked in only 13 observations.


4. Area under curve as depicted in Table 5 of the article (61% for DAI and 67% for DHC) indicates poor discrimination ability of the tests.

In an ROC curve, an area of 1 represents a perfect test; an area of 0.5 represents a worthless test.

According to rough estimates, an AUC value 0.60–0.70 shows poor accuracy of a diagnostic test, as no realistic classifier should have an AUC less than 0.5 (Fawcett [4]).


Under the circumstances, we do not agree with the conclusions of the authors that DHC and the DAI are reproducible and have reasonable accuracy and would recommend a rethinking of the applicability of DHC and DAI as per the results shown by the authors.


In response to the Commentary submitted by Arora et al. [ 1], which has questioned some methodological issues in our article [2], we would like to respond item by item.


(1) Arora et al. have pointed out that we performed a study with a prevalence of orthodontic treatment need (according to the gold standard) of 91%.

However, according to Table 4 of our study, the real prevalence of orthodontic treatment need is 52%.

Despite the fact that we chose the archives of Specialization Course in Orthodontics of a Dental School, this high prevalence (52%) is similar to the results of other studies because these validation studies are usually conducted in orthodontics settings, where study models are provided and where most cases for treatment are due to the need for diagnosis [3–6].

It is important to reinforce that we have also discussed these points in the second paragraph of page 3283.


(2) Arora et al. questioned “whether 9% casts shown to be not requiring orthodontic treatment were actually of subjects who did not require orthodontic treatment?” The models evaluated (n = 131) were a sample of 198 models of oral cavity of all orthodontic patients from Universidade Federal de Minas Gerais (first paragraph, page 3279).

These models pertained to patients who required orthodontic treatment in this University.


The clinical evaluation of orthodontic treatment need is a complex process which involves radiograph evaluation, facial evaluation, dental evaluation, and desires [7].

The gold standard of orthodontic treatment need in our study was determined by a consensus of three experts.

These experts have evaluated dental models.

This evaluation is quite different to a clinical orthodontic diagnosis.


So, the prevalence of patients without orthodontic need (48%) was not a surprise for us.


(3) Considering that the prevalence of orthodontic treatment need was not 91%, as pointed out by Arora et al., this simulation of accuracy is not relevant.


(4) To evaluate reproducibility we examined 13 models.

In the literature concerning reproducibility of occlusal indexes there is no unique option regarding sample size.

Beglin et al. [ 5] and Firestone et al. [ 8] evaluated 40 dental models in order to measure reproducibility.

Ovsenik and Primoziv [3] on the other hand studied 10 models.

In this regard, our methodology lies between these extremes presented in the literature.


(5) The last issue is related to the validity evaluation.

The ideal value of an Area Under Curve (AUC) is 1.0.

The statistical program that we have used measured the AUC for both indexes and the 95% confidence intervals (95% CI).

These confidence intervals indicated if the curve crosses the non-significant 0.5 value at any point.

Considering that 95% CI for both indexes did not cross the non-significant 0.5 value, we sustain that both indexes present reasonable (not perfect) accuracy [9].


It is important to reinforce that we discuss the limitations of our study in the last paragraph, page 3284.

However, we cannot accept the criticisms laid out in this Commentary.


A 2017 study by Goyal et al 11 showed that there was a disparity between the demand for photo- therapy and the time devoted to learning it during residency.

Responses obtained from dermatology program directors across the United States showed that a majority (67%) regarded their phototherapy training as inadequate, which was primarily attributed to time deficiency.

11 A cross-sectional survey 12 among US dermatology residents, published in 2015, showed that approxi- mately 59% did not obtain any hands-on photo- therapy training and that 42% had never observed phototherapy at all.

Fewer than half of the residents felt that they could comfortably administer NB-UVB unsupervised, and fewer than 20% were comfortable with administering other modalities (excimer laser, PUVA, and BB-UVB).


Similarly, in 2015, Anderson et al 13 found that, among US dermatology residents, 29% and 76% were not comfortable with prescribing outpatient and home phototherapy, respectively.

This discomfort stemmed from a lack of exposure and is significant because dermatology trainees who do not develop enough confidence to prescribe phototherapy during residency are less likely to do so in practice.


Phototherapy primarily uses UV radiation.

Depending on the pathogenesis of the disease being treated and the specific modality prescribed, phototherapy counteracts the pathologic changes that char- acterize inflammatory skin diseases through several key mechanisms: (1) induction of apoptosis, (2) modification of the cytokine milieu, and (3) immunosuppression.

14-16 Phototherapy has been used successfully to treat many skin diseases.

A partial list is shown in Table I.


Among these, photo- therapy for psoriasis has the most data.

The different modalities that can be used for psoriasis are BB-UVB, NB-UVB, excimer light or laser, and PUVA (oral, topical, hand-foot soak, and bath/full-body soak).

17 BB-UVB is rarely used today and has largely been replaced by NB-UVB because of the latter's better efficacy.

18 Oral PUVA has superior efficacy to NB-UVB for psoriasis.


Treatment with NB-UVB can produce substantial improvement of moderate to severe psoriasis after approximately 20 to 36 treatments, whereas oral PUVA can generate equal or better results after a median of 16 to 17 sessions.

18 In a systematic review by Almutawa et al, 17 oral PUVA achieved the highest clearance rate (CR) (79%) but caused symptomatic erythema and blistering in 17% of patients.

NB-UVB attained a 68% CR and was better tolerated (adverse effects in 7.8%), and bath PUVA was the least effective (58% CR) and least tolerated (adverse effects in 21%).

Hence, although oral PUVA is more efficacious, better tolerability makes NB-UVB a preferred first-line phototherapy modality.

17 In practice, the high cost and intermittent availability of 8-methoxypsoralen in the United States, together with well-known, long-term adverse effects of photoaging and photocarcinogenesis, have further limited the use of PUVA.


Excimer Torres et al areas such as the scalp, palms, and soles.

4 It can produce results with as few as 8 treatment sessions compared to conventional NB-UVB, thereby reducing the cumulative UV dose.

4,18 Outside the realm of psoriasis, NB-UVB is a first-line UV-based treatment option for many conditions including vitiligo, early mycosis fungoides, and atopic dermatitis.

UVA1 penetrates deeper into the dermis and has shown benefit for sclerosing skin disorders such as morphea and scleroderma.

19 NB-UVB and UVA1 are also useful for therapeutic hardening of patients with polymorphous light eruption and solar urticaria, respectively.

20 For treatment-resistant dermatitis of the hands and feet, topical PUVA is frequently used.

Oral PUVA is helpful for plaque stage mycosis fungoides, other forms of cutaneous lymphoma, and as a second-line UV-based treatment option for recalcitrant skin conditions that have failed or responded inadequately to NB-UVB.

21 The list of photoresponsive dermatoses is long, which underscores the versatility of this treatment modality.


Biologics are injected or infused monoclonal antibodies that block specific proinflammatory cytokines or receptors implicated in the patho- physiology of psoriasis and other inflammatory diseases.

16,22 These agents are grouped according to their cytokine target(s) as follows: tumor necro- sis factor inhibitors (etanercept, infliximab, adalimumab, certolizumab), interleukin (IL) 12/ IL-23 inhibitor (ustekinumab), IL-17 inhibitors (secukinumab, ixekizumab, brodalumab), and IL- 23 inhibitors (guselkumab, tildrakizumab, risanki- zumab-rzaa).

22 A 2019 meta-analysis found risankizumab-rzaa to be the most efficacious bio- logic for psoriasis, followed by ixekizumab, gusel- kumab, and brodalumab.

23 Kim et al 24 noted that IL-17 inhibitors have the earliest onset of efficacy.

The fastest, brodalumab, attained a 50% reduction in Psoriasis Area and Severity Index score (PASI) in less than 2 weeks and a 75% reduction in PASI in 4 weeks.

The IL-17 inhibitors were also among the biologic agents that had the most sustained activity together with the IL-23 inhibitors and IL-12/23 inhibitor.


A comparative study by Inzinger et al 25 showed that the efficacy rates of oral PUVA were comparable to those of infliximab and exceeded those of etanercept, efalizumab, alefacept, adalimumab, and ustekinumab.

Additionally, a recent trial comparing patient-reported outcomes of NB-UVB versus adalimumab versus placebo showed that improve- ments in overall health-related quality of life scores were equivalent for both active interventions after 12 weeks.


The acute adverse effects of phototherapy are relatively minor and include pruritus, tenderness, erythema, tanning, and blister formation.

18 For PUVA, the application or ingestion of a photosensi- tizer can incite skin phototoxicity, nausea, and/or vomiting.

18 The true risk of UV-induced skin cancer has long been a subject of debate and is a cause of hesitation for patients and providers alike.

PUVA has been found to significantly increase the risk of squamous cell carcinoma in a dose-dependent manner, whereas the incidences of PUVA-induced melanoma and basal cell carcinoma are much lower.

14,27 NB-UVB and UVA1 have had no evidence of increased risk of photocarcinogenesis and are considered safe with proper supervision by most practitioners.

14,27,28 These risks can be mitigated via thoughtful patient and modality selection, proper dosing and dose adjustment, protection of uninvolved areas, moni- toring of cumulative UV dose, and periodic full-body skin examinations.

14 With the exception of PUVA, phototherapy does not require any pretreatment laboratory workup and can be safely administered to pediatric, elderly, and pregnant patients.


The adverse effects and safety of biologic medi- cations should also be considered.

With proper patient screening, biologics have shown good safety, particularly when compared to traditional systemic agents 24 ; however, long-term data are scarce.

infection because of the immunomodulatory effects of the medication.

Tumor necrosis factor inhibitors have specifically been associated with an elevated risk of tuberculosis, hepatitis B, lymphoma, and other malignancies, whereas IL-17 inhibitors have been shown to induce and exacerbate inflammatory bowel disease and increase the risk for mucocutaneous candidiasis.

24,29 Depression and suicidality have been reported among patients taking brodalumab, although evidence on causation remains controversial.

24,29 Furthermore, parenteral administration of biologics makes injection site and infusion reactions a possibility.

24,29 To minimize these risks, patients who are candidates for biologic therapy require workup before initiation and at regular intervals throughout treatment.

Laboratory tests consisting of a complete blood count, liver function test, hepatitis panel, and tuberculosis screening are regularly performed.

22,30 Additional tests may be warranted depending on patient-specific or medication-specific risk factors.

Recent guidelines suggest that certain biologic agents may be safely administered to pregnant, lactating, and pediatric patients; however, information regarding this is still limited.

22,31 The COVID-19 pandemic raised numerous questions regarding biologics' safety that lack clear, evidence-based answers.

Based on experience with HIV-positive patients, and in keeping with the practice of social distancing, home phototherapy is a reasonable option during this pandemic.


The price of treatment is a reality that must be considered when formulating a management plan; and for chronic skin conditions, this may entail lifelong expenditures.

According to a study in Scotland, the average price for a course of NB-UVB is £257, whereas topical medications cost £128 annually per patient.

Implementing NB-UVB resulted in a 40% reduction in cost (£50.74 per patient annually) due to less need for medications.

32 A 2010 analysis estimated that biologics cost at least twice as much as NB-UVB and PUVA combined.

The least expensive biologic included in the study, adalimumab, was quoted at $23,538 for the first year of therapy alone, compared to $3148 and $7582 for a year of NB-UVB and PUVA, respectively.

33 Six years later, the price of adalimumab increased by more than 2-fold ($58,045) for the first year of therapy alone.


Home phototherapy units cost anywhere between $2500 and $5000.

35,36 They can offset the indirect expenses incurred from office-based treatment (transportation, lost income from work absences, inconvenience), but a disadvantage is that patients must pay for the device up front because few insurance policies offer coverage.

A comparative study showed that although in-office phototherapy was less costly at the beginning of treatment, it became 5 times more expensive than home phototherapy after 3 months.

36 Additionally, when compared to biologics, home phototherapy cost up to 36 times less over a 3-year period.


Biologics have remarkable efficacy and a good safety record to date, and they are convenient to administer.

This may provide rationale for physicians and patients to justify the high cost, especially when factoring in the intangible phototherapy expenses.

However, some patients may respond inadequately to biologic therapy and require dose escalation or more frequent administration, thereby further increasing the cost of treatment.


In practice, treatments are often combined to enhance efficacy when rapid suppression of disease activity is desired or when monotherapy is insufficient to achieve and maintain control.

Several reviews and guidelines on psoriasis treatment have reported on the combination of phototherapy with various topical drugs, traditional systemic agents, and biologics.

14,16,38,39 With each medication having its own adverse effects, enhanced toxicity from combining 2 or more modalities is a possibility.

Contrarily, some combinations of medications may lower the chances of long-term adverse effects by reducing the cumulative dose of either modality alone or have minimal to no additive toxicity because of the relatively short duration of adjunctive treatment.

38 The concomitant administration of acitretin with NB-UVB has been found to hasten clinical response, reduce the required acitretin dose, and decrease the number of phototherapy sessions by approximately 20%, thereby lowering the cumulative UV dose and theoretical risk for photocarcinogenesis.

14,38,40 Similar effects have been observed with acitretin plus PUVA, and given the established skin cancer risk with this modality, the coadministration of an oral retinoid is particularly valuable.

40-43 Because retinoids have a keratolytic effect, phototherapy dose escalations must be proceeded with cautiously when using this combination.

14 Most protocols recommend UV dose reduction by 33%.


Several studies have shown that NB-UVB in conjunction with biologics is safe, synergistic, and well tolerated, although long-term data on these combinations have not been explored.

Patients with moderate to severe psoriasis who complied with J AM ACAD DERMATOL FEBRUARY 2021 482 Torres et al thrice-weekly NB-UVB in addition to etanercept showed biopsy-proven improvement without addi- tional adverse effects compared to etanercept alone.

38,44 Moreover, a half-body comparison of adalimumab plus NB-UVB versus adalimumab alone yielded a 33% greater PASI reduction on the irradiated body half compared to the nonirradiated half. 45 Analogous results were obtained in a similar trial on ustekinumab.

46 Erythema was the most common adverse effect.

45,46 To date, there are no studies on the combination of PUVA with any biologic.


One major challenge concerning adherence to phototherapy is limited access.

In the United States, phototherapy facilities are concentrated in urban areas of the East and West Coasts and the Midwest region east of Mississippi, leaving 89% of counties without a treatment center.

6 This misdistribution appears to reflect the geographic location of dermatology providers in general and not the underuse of phototherapy per se.

Nonetheless, the indirect costs of travel and lost income from missing work can discourage patients from complying with repeated phototherapy treatments.

6 Other limiting factors are the resources needed to establish a phototherapy center (equipment, space, trained staff) and the need for prior authorization.


Home phototherapy devices can potentially address these hurdles.

Several randomized trials have shown that home-based and office-based phototherapy are equally safe and effective, with higher satisfaction and adherence in favor of home phototherapy; however, this also entails higher up-front costs for the patient and the need for a provider who is sufficiently familiar with home phototherapy.

47 In addition, photother- apy has possible long-term risks.

Therefore, in practice, it is usually administered intermittently, and patients may experience disease relapses within weeks to months of discontinuation.

Combining phototherapy with other modalities can not only decrease the likelihood or severity of a relapse but also lower the risk of adverse effects from either modality alone.

With proper patient education, home-based phototherapy is another option.


The advantages and limitations of phototherapy and biologics are summarized in Table II.


Phototherapy remains an indispensable treatment option for many cutaneous diseases.

Its versatility, cost effectiveness, and unparalleled safety makes it a viable first-line treatment or adjunct when other treatment regimens fall short.

Just as there are numerous indications for phototherapy alone, there are a wide variety of modalities with which it can be combined.

As dermatologic management becomes more individualized and costly, improved access to this treatment modality through expanding residency training curricula and prescribing of home devices will prove that even in the era of biologics, phototherapy will stand the test of time.

Dermatologists are the only group of physicians who have the knowledge and expertise to supervise the delivery of phototherapy.

Therefore, it is essential that we as a specialty continue to make sure this treatment option is available to our patients.


The article 'Role of phototherapy in the era of biologics' underscores the safety and efficacy of an established treatment among exponentially increasing options [1].

In this review, it was stated that narrowband ultraviolet B (NB-UVB) in conjunction with biologics has been considered safe.

Our findings raise questions about this opinion, particularly for antitumor necrosis factor (TNF) agents [2].


Prolonged immunosuppression by ultraviolet radiation significantly increases the risk of skin cancers.

In the transplantation literature, the cumulative incidence of skin cancers has ranged from 40% to 70% at 20 years [3].

UVB is particularly responsible for the immunomodulatory features of phototherapy; thus, the combination of immunosuppressive agents with relatively safe-considered NB-UVB should also be evaluated with caution.


TNF-α has been implicated in photocarcinogenesis [4], so it was hypothesized that anti-TNF agents might provide protection against the effects of DNA damage induced by UVB irradiation.

Faurschou et al. investigated the effects of TNF-α and infliximab in UVB-irradiated HaCaT keratinocytes and, as an interesting finding, both groups showed increased levels of DNA damage compared to that of the control group [5].


Our research group conducted a study in SKH-1 mice to test the potential of several immunosuppressive agents (infliximab, etanercept, and cyclosporine) to enhance UVB-induced carcinogenicity [2].

For the initial 10 weeks, mice were irradiated by a targeted UVB device.

The spectral output of this device peaks at 302 nm and 312 nm, with an average wavelength of 304 nm.

A predetermined minimal erythema dose was applied thrice per week before the administration of treatment agents.

The combination of the experimental drug and phototherapy was continued for an additional period of 14 weeks.

Drug doses were based on published effective doses in rodents, and the frequency of the applications was reproduced from the scheme for patients with psoriasis.

In a total experimental period of 24 weeks, higher tumor burden and keratinocytic neoplasia numbers were detected in the etanercept group.

The lack of statistical significance for other active treatment groups might be related to the small group sizes.


While the results cannot be extrapolated to the human situation, caution is advised.

Additionally, the light source and the timing of phototherapy were different from the clinical scenario because in studies evaluating this combination, NB-UVB phototherapy was initiated with the introduction of anti-TNF agents, and cessation of phototherapy was considered in the third month.


To the Editor: We read with interest and appreciation the commentary of Botsali [1], which expounds on the potential harm associated with the combination of narrowband ultraviolet (UV) B (NB-UVB) phototherapy and immunosuppressive agents, specifically, tumor necrosis factor inhibitors (anti-TNF).

Having been around for more than 4 decades, phototherapy has a well-known efficacy and long-term safety profile.

Because immunosuppression is one of the key mechanisms by which phototherapy controls inflammatory skin diseases [2], the risk of immunosuppression and subsequent cancer development is of particular concern, especially when phototherapy is combined with systemic immunosuppressive therapies.

Although it has been found that photochemotherapy with psoralen plus UVA significantly increases the risk of keratinocyte carcinomas, there has been no such evidence for NB-UVB monotherapy [2].

A retrospective study of more than 3000 patient records found no significant association between NB-UVB and the development of melanoma and keratinocyte carcinomas [3].

The median number of phototherapy sessions was 29, which approximates a typical course in clinical practice wherein substantial improvement in skin lesions is seen [2,3].

Previous human studies have also shown that the combination of NB-UVB with anti-TNF agents or other biologics is relatively safe [2].

However, given the lack of long-term data on these combinations, it is reasonable to proceed with caution.


Of note, concomitant therapy with NB-UVB and biologics is typically done in clinical practice for only a few months.

Concerns regarding immunosuppression are of special importance amidst the ongoing COVID-19 pandemic.

Patients may opt to discontinue treatment and risk having a disease flare because of fears of contracting the virus.

According to a recent study by Veenstra et al [4], patients on immunosuppressive medications (including anti-TNF agents) for various immune-mediated inflammatory conditions (including psoriasis) did not show a significantly elevated risk of acquiring COVID-19 or having a more severe disease course compared to the general population.

In addition, anti-TNF therapy was associated with a decreased likelihood of hospitalization due to COVID-19 [4].

The study did not account for patients who are on topicals or phototherapy in addition to immunosuppressive medications.

However, given that patients who are on immunosuppressive drugs often have moderate to severe skin disease, it is possible that these patients have a current or previous course of phototherapy.

Moreover, based on clinical experience with HIV-positive patients, phototherapy is a safe and reasonable option during this time [2].


Finally, care must be taken when extrapolating data obtained from in vitro or animal studies into clinical practice.

The mouse study conducted by Botsali and colleagues provided valuable insight into the potential additive carcinogenic effect of combining NB-UVB with anti-TNF agents [5].

However, as the commenting author recognized, these results cannot be readily applied to the human population.

This is because although useful information can be obtained from in vitro or animal models, they often lack the intricacies and complex interplay of human anatomy and physiology.

In summary, the aim of the review ‘‘Role of Phototherapy in the Era of Biologics’’ was to emphasize the utility, cost effectiveness, and versatility of phototherapy as a treatment option.

Because no therapeutic modality is completely devoid of risk, appropriate adjustments should be made on a case-to-case basis.


There is a statement in the introduction of the commu- nication that many breakfast cereals are 'energy-dense and nutritionally poor' (1) .

This statement cannot be sub- stantiated.

In fact, many, if not most, ready-to-eat cereals are nutrient rich, containing 25 % of the recommended dietary intake for many B vitamins, folate and Fe.

Break- fast cereal is one of the best sources of dietary Fe for both Kiwi adults and children (2,3) .

It is also well known that breakfast cereal eaters have higher nutrient intakes than those who skip or eat other foods for breakfast (4) .

They are also more likely to meet their fibre targets (4) .

Many ready- to-eat cereals, oats and muesli products are high in whole grains and often contain nuts and seeds, which further contribute to their intrinsic nutritional value.


The communication also states that many cereals in the New Zealand market are high in fat (1) .

There are very few breakfast cereal products in the market that would qualify as 'high in fat', for which there is no criterion for mea- surement in New Zealand.

The highest mean fat content in Table 1 in the communication is for muesli at 16·5 % or less than 8 g per 45 g serving.

In addition, less than one-third of the total fat is coming from saturated fat, indicating the use of non-saturated sources of fat by manufacturers.


The introduction to the communication also implies that there is no governance of breakfast cereal manufacture or labelling in New Zealand other than under Standard 1.2.7 in the Australia New Zealand Food Standards Code (1) :


'There is no regulation of formulation, labelling or promotion of breakfast cereals in NZ.

However, Food Standards Australia New Zealand (FSANZ) implemented Standard 1.2.7 in 2016, which requires that health claims be present only on foods meeting a Nutrient Profile Scoring Criterion (NPSC) score of <4.'


This is not the case for regulation in New Zealand.

The nutrition labelling of all breakfast cereals in New Zealand is strictly regulated under Standard 1.2.8 of the Code (5) .

In conjunction, the addition of vitamins and minerals is regulated in Standard 1.3.2 and there are other stipulated requirements for cereals in Standard 2.1.1.

There are fur- ther requirements which manufacturers must meet for allergen warnings and advisory statements as well as the use of novel ingredients.

What is more, not all cereals are required to meet NPSC as part of Standard 1.2.7.

Since nutrient content claims are governed under this standard, and do not require a passing of the NPSC.


The increases in mean total fat and energy in flakes and muesli shown in Table 1 of the communication would not come as a surprise to many working in food devel- opment in the cereal category.

The use of ingredients with more whole grains, nuts and seeds is evident across the category, largely due to innovation.

This would explain increases in energy, total fat and saturated fat in products that were generally low in fat and saturated fat to begin with.

In fact, when it comes to flakes, puffs and bubbles, there is little opportunity to increase fat in these products other than with the addition of nuts, seeds and wholegrain clusters.

Growth in granola and muesli, which are largely oat based and incorporate nuts and seeds, is also evident with the New Zealand market showing 30 % growth over the last 5 years (6) .

The addition of coconut to many cereals, which is also based on consumer demand, contributes to the fat and saturated fat contents.


Therefore, an increase in the mean energy, total fat or saturated fat content of the category is not a reliable indicator of a negative change in healthfulness.

In fact, if anything, the ingredient profiles of many cereals have been improved with the use of more whole ingredients having healthier fat profiles.


With respect to changes in protein in this category, it is not realistic to look for significant changes in a cate- gory that is largely grain based.

The addition of nuts can help together with soya crisps and pea protein, but this is likely to be in a small group of variants.

It is therefore unlikely that protein in this category will shift very much over time.


The discussion section of the communication explicitly states that a serving of breakfast cereal exceeds recom- mended intakes for sugar, Na and fat (1) :


'Unlike the USA, there appears to be little impetus in either Australia or New Zealand to reformulate breakfast cereal into a healthier product, despite the fact that one bowl of cereal can exceed the recom- mended dietary intake of sugar, Na and fat.'


The Daily Values (DV) or Reference Intakes used in the Food Standards Code are 90 g for sugars, 2300 mg for Na and 70 g for fat, with 24 g of that from saturated fat based on a diet of 8368 kJ/d (2000 kcal/d) (5) .

It is unlikely that a bowl of cereal would exceed these amounts, especially since one serving is likely to be between 30 and 45 g of cereal.

Even two servings of any cereal product would not reach the DV.

In fact, a breakfast cereal with 30 % sugar would provide 9 g of sugar per serving, which equates to 10 % of the 90 g DV for sugar.


The original communication references the 'added sugar or free sugars' recommendation from the WHO (10 % of energy intake from 'added or free' sugars) as the 'recommended dietary intake for total sugars' (1) .

Even in applying this recommendation correctly, it would equate to approximately 50 g of added sugars for adults, 25 g for young children and up to 50 g for teenagers.

There is currently no cereal that would reach those levels of added sugar in a serving or even in two servings.

What is more, the most recent national nutrition surveys in New Zealand showed that breakfast cereals contribute less than 3 % of total daily sugar intakes in New Zealand adults (2) and 3 % in children (3) .


This is also true for fat and saturated fat, given that the DV are 70 g and 24 g, respectively.

There is no cereal on the market that would exceed 70 g of fat or 24 g of saturated fat in a serving, particularly since the serving size is likely to be between 30 and 45 g.


The same logic would then apply to Na with a serving of cereal supplying under 200 mg, which equates to approximately 10 % of the suggested dietary target (7) .


The statement from the communication listed above is not factual and is void of reality.


The definition of reformulation according to the Oxford Dictionary is to 'formulate again or differently'.

This assumes that you are changing an already existing product.

To address reformulation, you would have to examine the same products over time.

Addressing reformulation performance based on mean nutrient intakes assumes a level of stability in the market, a stability that we cannot guarantee.

In addition, the methodology used in the communication is likely to dilute intra-individual variances over time.

This, combined with the shifting sample group, makes this assessment of reformulation problematic.


The authors of the original communication do acknowledge that individual reformulations were not possible to assess, which makes the conclusion that cereal manufacturers are not doing anything to reformulate their foods a rather broad assumption (1) .

Using average changes in nutrient contents across a dynamic category, to draw this conclusion, is prone to error.

In fact, it is likely that there was rapid innovation taking place in this category over the last 5 years.

This is evident from the entry of new brands, which is not recognised in the communication and could explain changes in mean intakes.


The breakfast cereal category has changed substantially over the years.

Na has been reduced across the category in line with recommendations; some of the largest brands in New Zealand have reduced their sugar content (8) and manufacturers are adding more whole ingredients such as whole grains, nuts and seeds.

All of this contributes to diverse and nutritious options becoming available to the New Zealand market.


The communication has made a number of untrue and misleading statements about the breakfast cereal category and the authors need to provide clarity for readers around their conclusions, particularly those statements regarding cereal exceeding recommended intakes.


We write this letter in response to a short communication entitled ‘The nutritional quality of New Zealand breakfast cereals: an update’, published in the December 2017 journal [1].

There are a number of misrepresentations of the New Zealand breakfast cereal category in the communication that need to be addressed by the authors.

Breakfast cereals contribute valuable nutrients to the Kiwi diet.

There is a statement in the introduction of the communication that many breakfast cereals are ‘energy-dense and nutritionally poor’ [1].

This statement cannot be substantiated.

In fact, many, if not most, ready-to-eat cereals are nutrient rich, containing 25% of the recommended dietary intake for many B vitamins, folate and Fe.

Breakfast cereal is one of the best sources of dietary Fe for both Kiwi adults and children [2,3].

It is also well known that breakfast cereal eaters have higher nutrient intakes than those who skip or eat other foods for breakfast [4].

They are also more likely to meet their fibre targets [4].

Many ready-to-eat cereals, oats and muesli products are high in whole grains and often contain nuts and seeds, which further contribute to their intrinsic nutritional value.

The communication also states that many cereals in the New Zealand market are high in fat [1].

There are very few breakfast cereal products in the market that would qualify as ‘high in fat’, for which there is no criterion for measurement in New Zealand.

The highest mean fat content in Table 1 in the communication is for muesli at 16.5% or less than 8 g per 45 g serving.

In addition, less than one-third of the total fat is coming from saturated fat, indicating the use of non-saturated sources of fat by manufacturers.

Cereal manufacture and labelling are regulated under the Australia New Zealand Food Standards Code.

The introduction to the communication also implies that there is no governance of breakfast cereal manufacture or labelling in New Zealand other than under Standard 1.2.7 in the Australia New Zealand Food Standards Code [1]: ‘There is no regulation of formulation, labelling or promotion of breakfast cereals in NZ.

However, Food Standards Australia New Zealand (FSANZ) implemented Standard 1.2.7 in 2016, which requires that health claims be present only on foods meeting a Nutrient Profile Scoring Criterion (NPSC) score of <4.

’ This is not the case for regulation in New Zealand.

The nutrition labelling of all breakfast cereals in New Zealand is strictly regulated under Standard 1.2.8 of the Code [5].

In conjunction, the addition of vitamins and minerals is regulated in Standard 1.3.2 and there are other stipulated requirements for cereals in Standard 2.1.1.

There are further requirements which manufacturers must meet for allergen warnings and advisory statements as well as the use of novel ingredients.

What is more, not all cereals are required to meet NPSC as part of Standard 1.2.7.

Since nutrient content claims are governed under this standard, and do not require a passing of the NPSC.


Mean energy, total fat and saturated fat are not reliable indicators of the healthfulness of the category.

The increases in mean total fat and energy in flakes and muesli shown in Table 1 of the communication would not come as a surprise to many working in food development in the cereal category.

The use of ingredients with more whole grains, nuts and seeds is evident across the category, largely due to innovation.

This would explain increases in energy, total fat and saturated fat in products that were generally low in fat and saturated fat to begin with.

In fact, when it comes to flakes, puffs and bubbles, there is little opportunity to increase fat in these products other than with the addition of nuts, seeds and wholegrain clusters.

Growth in granola and muesli, which are largely oat based and incorporate nuts and seeds, is also evident with the New Zealand market showing 30% growth over the last 5 years [6].

The addition of coconut to many cereals, which is also based on consumer demand, contributes to the fat and saturated fat contents.

Therefore, an increase in the mean energy, total fat or saturated fat content of the category is not a reliable indicator of a negative change in healthfulness.

In fact, if anything, the ingredient profiles of many cereals have been improved with the use of more whole ingredients having healthier fat profiles.

With respect to changes in protein in this category, it is not realistic to look for significant changes in a category that is largely grain based.

The addition of nuts can help together with soya crisps and pea protein, but this is likely to be in a small group of variants.

It is therefore unlikely that protein in this category will shift very much over time.

A bowl of breakfast cereal is physically unable to exceed daily nutrient targets.


The discussion section of the communication explicitly states that a serving of breakfast cereal exceeds recommended intakes for sugar, Na and fat [1]: ‘Unlike the USA, there appears to be little impetus in either Australia or New Zealand to reformulate breakfast cereal into a healthier product, despite the fact that one bowl of cereal can exceed the recommended dietary intake of sugar, Na and fat.’ The Daily Values (DV) or Reference Intakes used in the Food Standards Code are 90 g for sugars, 2300 mg for Na and 70 g for fat, with 24 g of that from saturated fat based on a diet of 8368 kJ/d (2000 kcal/d) [5].

It is unlikely that a bowl of cereal would exceed these amounts, especially since one serving is likely to be between 30 and 45 g of cereal.

Even two servings of any cereal product would not reach the DV.

In fact, a breakfast cereal with 30% sugar would provide 9 g of sugar per serving, which equates to 10% of the 90 g DV for sugar.

The original communication references the ‘added sugar or free sugars’ recommendation from the WHO (10% of energy intake from ‘added or free’ sugars) as the ‘recommended dietary intake for total sugars’ [1].

Even in applying this recommendation correctly, it would equate to approximately 50 g of added sugars for adults, 25 g for young children and up to 50 g for teenagers.

There is currently no cereal that would reach those levels of added sugar in a serving or even in two servings.

What is more, the most recent national nutrition surveys in New Zealand showed that breakfast cereals contribute less than 3% of total daily sugar intakes in New Zealand adults [2] and 3% in children [3].

This is also true for fat and saturated fat, given that the DV are 70 g and 24 g, respectively.

There is no cereal on the market that would exceed 70 g of fat or 24 g of saturated fat in a serving, particularly since the serving size is likely to be between 30 and 45 g. The same logic would then apply to Na with a serving of cereal supplying under 200 mg, which equates to approximately 10% of the suggested dietary target [7].

The statement from the communication listed above is not factual and is void of reality.


Reformulation in the category has been happening for decades and is still continuing.

The definition of reformulation according to the Oxford Dictionary is to ‘formulate again or differently’.

This assumes that you are changing an already existing product.

To address reformulation, you would have to examine the same products over time.

Addressing reformulation performance based on mean nutrient intakes assumes a level of stability in the market, a stability that we cannot guarantee.

In addition, the methodology used in the communication is likely to dilute intra-individual variances over time.

This, combined with the shifting sample group, makes this assessment of reformulation problematic.

The authors of the original communication do acknowledge that individual reformulations were not possible to assess, which makes the conclusion that cereal manufacturers are not doing anything to reformulate their foods a rather broad assumption [1].

Using average changes in nutrient contents across a dynamic category, to draw this conclusion, is prone to error.

In fact, it is likely that there was rapid innovation taking place in this category over the last 5 years.

This is evident from the entry of new brands, which is not recognised in the communication and could explain changes in mean intakes.

The breakfast cereal category has changed substantially over the years.

Na has been reduced across the category in line with recommendations; some of the largest brands in New Zealand have reduced their sugar content [8] and manufacturers are adding more whole ingredients such as whole grains, nuts and seeds.

All of this contributes to diverse and nutritious options becoming available to the New Zealand market.

The communication has made a number of untrue and misleading statements about the breakfast cereal category and the authors need to provide clarity for readers around their conclusions, particularly those statements regarding cereal exceeding recommended intakes.


We wish to respond to a letter by Gina Levy of Kellogg (Australia) Pty Ltd – Research and Technology, Australia entitled ‘The New Zealand breakfast cereal category is dynamic and responsive to consumer preferences’, published in Public Health Nutrition [1] in response to our published article ‘

The nutritional quality of New Zealand breakfast cereals: an update’ [2].

We thank the author for her interest in our publication and will respond to several of her comments.


The above letter suggests a misrepresentation of the nutritional quality of breakfast cereals with our wording that many cereals can be ‘energy-dense and nutritionally poor’.

While we concur with Ms Levy that some ready-to-eat cereals contain moderate levels of natural and supplemental vitamins/minerals, as well as whole grains, nuts and seeds, our comment was in relation to the proportion of nutrients in these products and their alignment with the New Zealand recommended nutrient intakes from cereals.

Many of the New Zealand breakfast cereals analysed for our original publication had up to 30% of their energy content from sugar alone, with the Na content of some cereals being up to 350 mg per 100 g of product.

With New Zealand currently having a very high prevalence of obesity [3], the 30% sugar content of cereals, particularly those marketed towards children, is nutritionally poor, despite the fact that these cereals may offer whole grains as a primary carbohydrate source.


We acknowledge an ambiguity when we described a bowl of cereal as exceeding the recommended intakes for sugar and Na. We should have clarified that these levels can be exceeded when one considers the proportion of kilojoules and nutrients normally consumed in the breakfast meal alone.

It is documented that many cereal eaters (both adults and children) regularly consume more than the manufacturer-declared serving size in one sitting [4,5] and that children will voluntarily eat more of a high-sugar cereal (up to twice the recommended serving size) compared with a lower-sugar alternative [6].

When looking at the mean sugar values of children’s breakfast cereals in our New Zealand data set, the intake from double the recommended serving size, with 200 ml of milk, would equate to approximately 25 g sugar in one breakfast meal.

Ms Levy acknowledged that a child’s maximum sugar intake should be approximately 25 g/d (based on WHO recommendations that sugar should not exceed 10% of daily energy intake [7]).

Thus, a child’s total recommended daily sugar allowance could be consumed in this one meal alone.


The literature reports that increasing breakfast energy is associated with greater overall food intake in normal-weight and obese subjects, and that those who consume a large breakfast meal do not compensate by eating smaller meals later in the day [8].

Furthermore, it has been reported that children will readily consume lower-sugar cereals if offered to them [6,9] and our argument is that New Zealand manufacturers do not currently provide adequate low-sugar cereal options.

Except for ‘Biscuits and Bites’, the mean sugar content of all breakfast cereal categories in 2017 was 20% or more, suggesting that adults are also consuming a significant amount of sugar from their breakfast cereal meal (particularly when combined with milk and any added fruits or sugar).

The ‘adequate intake’ of Na has been shown to range from 200–400 mg in children aged 2–3 years, through to 460–960 mg in youth aged 14–18 years [10].

Thus, it is concerning that one 40 g serving of dry cereal can provide up to 200 mg Na, especially as Ministry of Health data report that Na from breakfast cereals accounts for only 6% of the daily Na intake [11].

If those eating high-sugar cereals are indeed eating up to double the recommended serving size as suggested previously [6], then the Recommended Daily Intake (RDI) of Na for younger consumers is also being reached after consumption of the breakfast meal alone.


The Ministry of Health in New Zealand currently recommends that high-fat, -sugar and -salt (HFSS) foods and drinks should be consumed no more than once per week [10].

Yet, breakfast cereals are generally marketed as being foods that can be consumed on a daily basis.

Certainly, not all New Zealand breakfast cereals would be termed a HFSS food based on their sugar, fat or Na content, but a large proportion would be based on our data collected in 2017.

This is also concerning, as New Zealand television advertising shows proportionately twice as many breakfast cereals advertisements as Australia [12].

It is also a worry that promotional characters used to market cereals are more likely to feature on cereals calculated to be ‘less healthy’ when using Nutrient Profile Scoring Criterion scores [13].


We acknowledge Ms Levy’s comments about a lack of data to support our statements about product reformulation, and this was noted as a limitation in our original publication.

However, as we did not have access to individual product details from the original 2013 data set, we were unable to determine whether specific product reformulations had taken place.

Despite this, we suggest that the lack of change seen at the category level in our data is still indicative that little has been done at a manufacturer level to reduce the content of sugar and Na of many breakfast cereals.

We agree with Ms Levy that there have been new products and brands entering the breakfast cereal category during the last 5 years, and suggest a more robust study should be undertaken to evaluate whether existing products have had their nutritional profiles altered in recent years in an attempt to align with suggested New Zealand RDI.


Interestingly, Ms Levy focused on one particular in-house cereal example (Nutri-Grain®) and reported that the manufacturer (Kellogg’s) has reduced the sugar content of this product.

However, the data sourced to support this claim are from an Australian website and no evidence has been provided that this change has also occurred in the New Zealand product.

Furthermore, Nutri-Grain has previously been criticised by the Obesity Policy Coalition for its level of sugar, being the highest of ten children’s cereals surveyed [14], suggesting that this one product alone may have been targeted for reformulation.

The reformulated Nutri-Grain product discussed in the letter still contains 26.7% sugar, so the reformulation has not fully redressed the issue of excessive sugar in the cereal.

Further, Ms Levy did not provide any information that other cereals had been reformulated in recent years (either Kellogg’s or any other brand) and a search of both the Internet and published literature could not identify any other information or press releases about cereal companies in New Zealand reducing their sugar content.


We would like to acknowledge that we misrepresented that there is no regulation of food labelling in New Zealand and thank Ms Levy for clarifying this point.

However, the emphasis of this statement in the original publication was on the lack of regulation of product formulation and promotion of breakfast cereals.

Currently, there is little control of the nutritional quality of breakfast cereals in New Zealand and this appears to be largely manufacturer-driven in response to customer demand.

However, it is our belief that manufacturers should take some responsibility for the provision of healthier breakfast cereals (including cereals with a lower sugar content), particularly as the published literature demonstrates that consumers will still readily purchase and consume such products.