Subgroup disparities in the mediating roles of income and social support between education level and depressive symptoms among Chinese middle-aged and older adults: an analysis based on the China health and retirement longitudinal study

Objectives This study aimed to identify potential subgroups and explore how the mediating effects of income and social support in the relationship between education level and depressive symptoms vary across these groups among middle-aged and older Chinese adults. Design This study used statistical learning techniques to analyse data from the China Health and Retirement Longitudinal Study (CHARLS), adopting a cross-sectional approach.

Setting The study analysed data from the 2011 baseline survey of CHARLS. Depressive symptoms were evaluated based on the Centre for Epidemiologic Studies Depression Scale form.

Education, social support (informal social support, community support and public support), lifestyle choices (smoke, alcohol and social activity), health conditions (hypertension, dyslipidaemia, diabetes, lung disease, heart problem, kidney disease, digestive disease, arthritis, disability, pain and activity limitation), demographic background (urban residence, sex, age, marital status, body mass index and retirement status) were included in the analysis. Participants 8161 adults over the age of 45 were included.

Primary outcome measures The primary outcome measure was the association between educational level and depressive symptoms mediated by income and social support.