Objective: To investigate the shape of the socioeconomic-oral health distribution using the MacArthur Scale of Subjective Social Status and equivalised household income.
Methods: Cross-sectional self-report data were collected by questionnaire in 2003 from adults aged 43-57 years living in Adelaide, Australia. A two-stage stratified, clustered, random sampling design was used to select individuals nested within 60 geographic areas. Values for subjective social status and equivalised household income were divided into quintiles. Oral conditions were: (1) <24 remaining teeth; (2) 1+ impact/s on the 14-item Oral Health Impact Profile experienced fairly often or very often; (3) fair or poor self-rated oral health; and (4) low satisfaction with chewing ability. Analyses of weighted data were conducted using SUDAAN to adjust for the sampling design. Prevalence ratios and their 95% confidence intervals (PR, 95%CI) for each oral condition were calculated from logistic regression models. Covariates were age, sex, country of birth, smoking, alcohol use, body mass index, frequencies of toothbrushing and interdental cleaning.
Results: A questionnaire was returned by 2,915 adults (69.4%). There was a linear gradient of decreasing prevalence for each oral condition across quintiles of increasing subjective social status. In the fully adjusted model the gradient was steepest for low satisfaction with chewing (PR= 4.1, 95%CI = 3.0-5.4). Using equivalised household income, a threshold effect was observed for all oral conditions. The steepest threshold was for adverse impacts of oral conditions (PR=3.0, 95%CI=2.0-4.6). Adjustment for covariates did not attenuate the magnitude of PRs.
Conclusion: The finding that subjective social status was associated with continuous gains in oral health status, while equivalised household income was associated with a threshold effect, supports the psychosocial explanation for socioeconomic health inequalities. Supported by NHMRC.