We are doing a prevalence study on Obstructive sleep apnea (OSA). There is an established association with neck circumference. Neck circumference increases with height and there is a variable called PPNC to correct for this. PPNC also has an established association with OSA
PPNC = (1000 × NC) / [(0.55 × Height) +310]
The parameter is actually calculating the percentage of the neck circumference to the predicted NC for the height. The original paper by Davies & Stradling, 1990 seems to be unavailable online. The correction equation suggested therein is population-dependent.
Would the correction be valid for the population under our study, if the value of PPNC for the controls (assumed normal) does not include the 100% (i.e. the predicted normal circumference) mark within +/- 1 SD?
Does it point to the fact that the correction is not valid for our population, since the predicted normal circumference value is not found even among the un-diseased population?
Or is there any other parameter which could be used in such a situation?
http://www.ncbi.nlm.nih.gov/pubmed/2376247
The abstract for the Davies and Stradling article states that only 66 subjects were studied. It is hard to believe that many E. Indians were among that group because it was published in a journal for Europe. Probably the numerical conclusions are not valid for your populations, but only a new study could prove that. Neck circumference is probably more dependent on weight or body mass index than height, at least for northern European populations. Even in U. S. Army females, the statistical distribution is not normal, and likely is not normal for any population where wide variations in weight for given height is possible because of diet options. Correlations between height or length dimensions and circumference dimension are typically quite low for many populations. It is not surprising that some way of accounting for differences in neck circumference are needed for any given height, such as the PPNC. Not everything that is published appears on the Internet. You might try looking for a copy of the pertinent journal in the library of a large university, or asking for a copy of it from such a university.
Thanks a lot John! Is it worth creating a new parameter that fits best for our population? We also have other anthropometric details like height, weight and waist circum for about a population of 300? Or is it pointless to do if we already have a correlation with neck circumference?
Hi Vasishta,
The following paper may be helpful to you
Comparison of Anthropometric Data Between Asian and Caucasian Patients With Obstructive Sleep Apnea: A Meta-Analysis.
Cho JH, Choi JH, Suh JD, Ryu S, Cho SH.
Clin Exp Otorhinolaryngol. 2016 Mar;9(1):1-7. doi: 10.21053/ceo.2016.9.1.1. Epub 2016 Mar 7. Review.
PMID:
26976019
Free PMC Article
The full paper is available on line at no charge through the search engine at www.pubmed.com .
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