Abstract
OBJECTIVE: We examined disparities in periodontal disease in U.S. adults according to age, sex, race/ethnicity, country of birth, education, income, and poverty-income ratio within and between the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994) and NHANES 1999-2004. METHODS: We assessed disparities and changes therein using prevalence differences and ratios, as well as the Symmetrized Theil Index (STI). While these measures document disparities between pairs of population subgroups, and changes in relative disparities between surveys, the STI is a summary measure of health disparities that also tracks between-group disparities relative to the total population. RESULTS: Prevalence differences and ratios for the prevalence of periodontitis, the mean pocket depth (PD), and the mean clinical attachment loss (CAL) suggest that periodontal disease significantly decreased between NHANES III and NHANES 1999-2004 (p<0.01). However, the STI for the prevalence of periodontitis suggests that disparities significantly increased within categories of race/ethnicity, country of birth, and education in NHANES 1999-2004 compared with NHANES III. These findings were corroborated for mean PD and mean CAL (p<0.001): the overall STI significantly increased for mean PD from 4.53% in NHANES III to 11.02% in NHANES 1999-2004 and for mean CAL for teeth with CAL >0 from 31.73% in NHANES III to 43.36% in NHANES 1999-2004. CONCLUSIONS: Our findings suggest that inequalities in periodontal disease significantly decreased between NHANES III and NHANES 1999-2004 in the total population and across selected characteristics of the population. However, these inequalities increased within groups of the population in NHANES 1999-2004 compared with NHANES III. These findings call attention to the absolute and relative differences not only between population groups across surveys, but also within population groups within and between surveys.