The role of welfare regimes on socioeconomic inequalities in edentulism: a cross-national analysis of 40 countries.

Background: We aim to evaluate the association between welfare regimes and edentulism (total tooth loss) and to investigate whether welfare regimes modify the magnitude of socioeconomic inequalities in edentulism. Methods: The Lancet Commission on Oral Health gathered and analysed nationally representative available data from 40 high, middle- and low-income countries, collected between 2007 and 2018. The study included 117,397 individuals 20 years or older. The outcome was edentulism, defined as the absence of all natural teeth. We categorised countries into seven welfare regimes, which served as both the primary exposure and an effect modifier. Individual-level variables included sex, age and a composite measure of socioeconomic position: "wealth" measured in quintiles. Inverse probability of treatment weight and multilevel logistic regression were employed to estimate the odds of being edentulous, and cross-level interaction terms between wealth and country factors. Findings: Individuals at the lowest wealth quintile had the highest prevalence of edentulism in all regimes. The highest age-sex standardised prevalence was found in Eastern European countries (8.4%, 95% Confidence Interval: 7.6-9.3), followed by Corporative (8.1%, 95% CI: 7.0-9.3), while the lowest was among the Insecurity regime (0.8%, 95% CI: 0.4-1.5), followed by the Scandinavian regime (4.7%, 95% CI: 3.5-6.1). Liberal countries presented the highest magnitude of absolute and relative inequalities, where the lowest quintile had OR = 20.6 (95% CI: 15.3-27.8) times higher likelihood of being edentulous and 17.3 percentage points (pp) higher prevalence. Low-income countries in the Insecurity regime presented the lowest level of inequality. Among high- and upper-middle income countries, the Scandinavian regime had the lowest absolute inequalities (5.5 pp difference between highest and lowest quintiles). The Informal Security regime had the lowest relative differences between the highest and lowest quintiles (OR = 2.20, 95% CI: 1.06-4.59). Interpretation: Our findings indicate that some welfare regime policies may enhance oral health while decreasing socioeconomic inequalities. Higher prevalence and inequalities among industrialised countries may reflect higher levels of oral health hazards. Funding: This was partially supported by a National Institute for Health and Care Research (UK) grant number 132731.