Educational inequalities in self-rated health and their mediators in late adulthood: Comparison of China and Japan.

Education has an impact on health, but the magnitude of the impact may vary across countries. This cross-sectional study compared educational inequalities in health and their mediators in late adulthood between China and Japan, which both face rapid population aging. We studied the same age cohort (63-72 years) based on two nationwide population-based surveys in 2018: the China Health and Retirement Longitudinal Study (N = 5,277) and Japan's Longitudinal Survey of Middle-Age and Elderly Persons (N = 20,001). The relative index of inequality (RII) in education was used to measure educational inequality in self-rated health (SRH). We then examined the extent to which income, smoking, leisure-time physical activity, and social participation mediated educational inequalities in SRH. In both countries, a lower educational level was associated with a higher risk of poor SRH; in China, however, the gradient was flatter. In China, the RII of education was 1.69 (95% confidence interval [CI]: 1.20-2.39) for men and 1.47 (95% CI: 1.06-2.05) for women. In Japan, meanwhile, RII was 2.70 (95% CI: 2.21-3.28) for men and 2.60 (95% CI: 2.13-3.18) for women. Our mediation analysis based on logistic regression models with bootstrapping also found that social participation was a key mediator of educational inequalities in health in both countries. In all, the results underscore that one's relative position in educational inequalities is a reliable predictor of subjective health in late adulthood in both China and Japan.