Yesterday, new NHANES 2009-2012 data on prevalence, extent and severity of periodontitis have gone online in the Journal of Periodontology. On first sight, authors confirm findings of the previous, 2009-2010, survey in that prevalence is much larger as previously reported. So, 46% of U.S. adults have periodontitis with almost 9% having severe disease (Eke et al. 2015). The previous report (Eke et al. 2012a) contained an unclear description of how attachment loss was measured concealing that a “signed” measure of recession was used to calculate clinical attachment loss as difference of probing pocket depth and recession (from Latin, recessus, retreat). In a letter to the Editor-in-Chief of the Journal of Dental Research, Professor Giannobile, I had raised more problems in the article when I wrote,
“Teaching in particular undergraduates about how probing parameters periodontal probing depth, attachment level, and recession are measured is quite an effort but usually straightforward. In order to avoid undue exaggeration of prevalence, extent and severity of periodontitis both in the population and in patients attending a common office and to be able to assess treatment outcomes, metric periodontal probing parameters have to be properly defined. I would therefore appreciate if authors could comment on the apparent redefinition of attachment loss in their paper. When analyzing the Figure in the paper by Eke et al. (2012a), what immediately hits the eye is that there seems to be higher prevalence of attachment loss at different thresholds (a) than of pocket depth at respective thresholds (b) in all age groups. Such a pattern may actually be a result of how attachment loss had erroneously been redefined, most probably due to convenience. Just as a trivial example, a 4 mm probing depth without recession may be associated with either 0, 1, 2, 3, or 4 mm attachment loss, but the NHANES oral health data management program would have “instantly calculated” 4 mm. Based on the new case definition using attachment loss in addition to probing depth, prevalence of all periodontitis in the adult population of 30 years and older in the U.S. has now been estimated to exceed 47%, after 35% found in NHANES III during 1988-1994. This much higher prevalence may be due to the redefinition of attachment loss, too. Moreover, as to Eke et al. (2012a), mild periodontitis has a rather low prevalence in all age groups while moderate periodontitis is widespread (Figure c). The picture was different in NHANES III when severe periodontitis occurred with lowest, moderate periodontitis with intermediate and mild periodontitis with highest prevalence, a pattern which, I suppose, applies to many other widespread chronic diseases. The strange new pattern might indeed be explained partly by the redefinition of attachment loss as well, ultimately leading to a different distribution of cases.” (Emphasis added.)
Subtracting recession from periodontal probing depth makes sense only when true recession (the free gingival margin is located apical to the cemento-enamel junction) gets a minus sign. This was circumstantially explained to me in an email by the authors forwarded to me by Professor Giannobile, who never published my original letter. Eke et al. (2012a) had actually concealed that a signed recession definition was used. In the new update of NHANES 2009-2012, calculation of clinical attachment is now correctly described, including the signed recession definition. Eke et al. (2015) may also have realized that there is no complex chronic disease where moderate severity is more prevalent than its mild form. It is rather perplexing to see that authors have now abandoned the differentiation between moderate and mild periodontitis which they call “other” periodontitis (other than severe). They give the following reason,
“These subgroups [mild and moderate periodontitis] are not truly ordinal [sic] as the label suggests because many ‘moderate’ cases had insufficient pocket depth to qualify as ‘mild’ and we have therefore combined them and used the label ‘other‘ periodontitis.”
As I have reported in my previous post, in the current controversy with authors of a recent update of prevalence of periodontal disease in the U.S. as observed in the 2009-2010 NHANES, the editor of Journal of Dental Research, Professor W. Giannobile, had expressed regrets that he has declined to publish either an Erratum or my letter [pdf]. According to Dr. Giannobile, authors had conceded that
“[T]he algorithm used to calculate attachment loss (AL) in NHANES can intuitively be misunderstood because it is stated that subtraction measures of gingival recession from measures of pocket depth PD (and not added as one would expect intuitively). However, mathematically this is correct. The recession is called out as a negative number by the examiner and is subtracted from the PD i.e., PD – (-recession) = PD + recession (if the FGM is below the CEJ) which adds up to the sum of the recession plus the PD. If the FGM is above the CEJ, then it is the direct sum of the recession (which is positive) and PD. Thus in NHANES, AL is calculated from three anatomical points versus a direct measure from the CEJ to the bottom of the pocket as may be done clinically (Clinical attachment loss). There is a long history behind why NCHS [National Center of Health Statistics] has used this approach, however this is how AL has been determined for all previous NHANES including NHANES III (the dataset used by Albandar 1999), NHANES 1999-2004 and NHANES 2009 – 2010.”
Honestly, I had not expected anything else. The authors actually claim that they had adopted the “long history” of how attachment loss had been determined, i.e. according to the correct albeit overly complicated approach used by Albandar et al. (1999) but, for the first time, mention “recession” rather than the distance between the cemento-enamel junction and the free gingival margin (which got a minus sign in case of exposed root surface). In my response I wrote,
“[I]f the ways how attachment loss have been determined had been identical in NHANES III and the 2009-2010 NHANES (and indeed any NHANES), one would expect either an apt quotation or a correct reference.
Note that Albandar et al. (1999) did not use the term “recession” at all in their description of what had been considered attachment loss. I find it very awkward that recession (from Latin recessus, retreat) can have a minus sign. I am afraid that future investigators outside the U.S. might refer to Eke et al. (2012) when falsely calculating attachment loss by intuitively and erroneously adding (rather than subtracting) recession and periodontal probing depth. See also the description, apparently written for lay people, of what is meant by recession and attachment loss in Dye et al. (2007) on p. 102 who compare NHANES III and 1999-2004 NHANES data:
“Recession: the presence of exposed [sic!] dental root, which is typically measured in millimeters from the free gingival margin (FGM) to the cemento-enamel junction (CEJ). The FGM is located along the top of the gum and the CEJ is the place on a tooth where the root and the tooth “crown” meet.
“Attachment loss (AL): the amount of connective tissue loss measured in millimeters (mm) from the CEJ to the sulcus base.”
I still would find a brief Corrigendum or Erratum or, say, Note regarding the paper by Eke et al. appropriate and helpful, which might state that attachment loss had been determined in an identical way as had been described by Albandar et al. (1999).
As regards my final suggestion, I am aware that case definitions by Albandar et al. (1999) did include furcation involvement which has not been assessed by Eke et al. (2012). So, direct comparison in order to conclude whether the situation has improved, is stable, or has actually deteriorated will in fact hardly be possible.” (Emphasis as such.)
I had been quite comfortable with teaching the results obtained in NHANES III (the population-based 3rd National Health and Nutrition Examination Survey the data of which had been collected between 1988 and 1994) for a long time. In a nutshell, for the adult, dentate (those with teeth) population of the United States Albandar and Kingman (1999) had reported that,
- gingival inflammation (as assessed by bleeding on probing) is widespread with increasing prevalence (at least one bleeding site) from 40-50% in 30 to 39-yr-olds to around 60% in 80-plus-yr-olds, as well as increasing extent (mean % teeth with gingival bleeding) from about 13 to 23%;
- likewise, calculus is widespread with prevalence in 90-95% of subjects and increasing, with age, extent from 40-50% to more than 60% teeth; and
- while males had significantly more gingival bleeding, more subgingival calculus and more teeth with either supra and subgingival calculus than females, non-hispanic blacks had the highest prevalence and extent of dental calculus.
When it comes to periodontitis, Albandar et al. (1999) observed that,
- at least 35% of the adult population were affected by the disease, but most cases (22%) were mild;
- moderate and advanced periodontitis affected not more than 13%;
- not surprisingly, prevalence and extent of attachment loss increased with age while in the oldest age group (80 yr and older), prevalence of deep pockets decreased because of tooth loss and recession; and,
- severe forms of the disease affected more men and more African Americans and Hispanics than Whites.