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.)
As I have mentioned in a previous post I had sent a letter to the editor of Journal of Dental Research, Professor W. Giannobile, in which I had asked the authors of a recent article on the periodontal findings of the 2009-2010 NHANES for some clarification regarding the quite confusing definition of attachment loss. There, Eke et al. (2012) wrote in the Material and Methods section,
“All periodontal examinations were conducted in a mobile examination center (MEC) by dental hygienists registered in at least one U.S. state. Gingival recession [= the distance between the free gingival margin (FGM) and the cemento-enamel junction (CEJ)] and pocket depth (PD) (= the distance from FGM to the bottom of the sulcus or periodontal pocket) were measured at 6 sites per tooth (mesio-, mid-, and disto-buccal; mesio-, mid-, and disto-lingual) for all teeth, excluding third molars. For measurements at each site, a periodontal probe (Hu-Friedy PVP 2TM, Chicago, IL, USA) with 2-, 4-, 6-, 8-, 10-, and 12-mm graduations was positioned parallel to the long axis of the tooth at each site. Data were recorded directly into an NHANES oral health data management program that instantly calculated attachment loss (AL) as the difference between probing depth and recession. Bleeding from probing and the presence of dental furcations were not assessed.” (Emphasis added.)
In my letter [pdf] I had pointed to (1) a possible glitch when calculating attachment loss as the difference, rather than the sum, between probing depth and recession; and (2) the fact that in the absence of any recession, periodontal probing depth must not automatically be regarded as attachment loss as the above description of the method suggested. I had provided a most trivial example regarding a 4 mm probing depth without recession which may be associated with either 0, 1, 2, 3, or 4 mm attachment loss, but it seems that the NHANES oral health data management program would have “instantly calculated” 4 mm. Then, (3) I had expressed my concern that either observation that attachment loss at certain thresholds was consistently higher than periodontal probing depth at respective thresholds in all age groups of the adult population of the United States, and the rather conspicuous finding that moderate periodontitis occurred at much higher prevalence than mild periodontal disease may in part be due to the apparently amended definition of attachment loss. And finally, as a constructive suggestion, (4) I asked the authors to compare the new 2009-2010 data with those of 1988-1994 by using the previous case definition (solely based on probing depth) by Albandar et al. (1999) in order to be able to “forget what I was told”, namely that prevalence, extent and severity of periodontal disease had in fact not decreased since NHANES III.