Measuring and decomposing oral health inequalities in an UK population

OBJECTIVES With health inequalities high on the policy agenda, this study measures oral health inequalities in the UK. METHODS We compare an objective clinical measure of oral health (number of natural teeth) with a self-reported measure of the impact of oral health (the Oral Health Impact Profile, OHIP) to establish whether the type of measure affects the scale of inequality measured. Gini coefficients and Concentration Indices (CIs) are calculated with subsequent decompositions using data from the 1998 UK Adult Dental Health Survey. Because the information on OHIP is only available on dentate individuals, analyses on the number of natural teeth are conducted for two samples - the entire sample and the sample with dentate individuals only, the latter to allow direct comparison with OHIP. RESULTS We find considerable overall pure oral health inequalities (number of teeth: Gini = 0.68 (including edentate), Gini = 0.40 (excluding edentate); OHIP: Gini = 0.33) and income-related inequalities for both measures (number of teeth: CI = 0.35 (including edentate), CI = 0.15 (excluding edentate); OHIP: CI = 0.03), and the CI is generally higher for the number of teeth than for OHIP. There are differences across age groups, with CI increasing with age for the number of teeth (excluding edentate: 16-30 years: CI = 0.01, 65 + years: CI = 0.11; including edentate: 16-30 years: CI = 0.01, 65 + years: CI = 0.19). However, inequalities for OHIP were highest in the youngest age group (CI = 0.05). Number of teeth reflects the accumulation of damage over a lifetime, while OHIP records more immediate concerns. CONCLUSIONS There are considerable pure oral health inequalities and income-related oral health inequalities in the UK. Using sophisticated methods to measure oral health inequality, we have been able to compare inequality in oral health with inequality in general health. The results provide a benchmark for future comparisons but also indicate that the type of health measure may be of considerable significance in how we think about and measure oral health inequalities.