Analysis of Multiple 2x2 Tables with Site-specific Periodontal Data

Periodontal data typically consist of observations made at multiple sites within each patient. Observations within a patient tend to be positively correlated; hence, standard statistical techniques that assume independence are invalid. Regression techniques for correlated data have been proposed; communicating results from these models, however, is difficult, due to their inherent complexity. Simpler statistical approaches have also been proposed, but many of these methods can be applied only when covariates are specific to the subject, and do not vary from site to site within a subject. In this paper, we present two methods for the analysis of multiple 2x2 tables containing site-specific periodontal data. The methods presented are modifications of the well-known Mantel-Haenszel methods. We illustrate these methods using a subset of data from a clinical trial examining the effects of scaling and root planing on levels of interleukin-1β.