Background: Health inequality is seen as a challenge for implementing the Healthy China Strategy. This study analyzes the income-related health inequality among urban–rural resident basic medical insurance (URRBMI) participants. Methods: This study utilized data from the 2019 China Household Finance Survey (CHFS), and the concentration index (CI) was employed to estimate the effects of income-related health inequality on participants. Results: Our findings provide clear evidence that health inequality among participants has fluctuated—narrowing, widening, and then narrowing again—in the areas of the contribution, medical treatment, and reimbursement of URRBMI, respectively. Overall, the analysis indicates a widening of health inequality post-reimbursement, with results remaining consistent. A heterogeneity analysis shows that health inequality is most pronounced among women and those with less than a middle school education. Finally, our study reveals a pro-rich trend in the actual utilization of medical services among participants, with persistent disparities in outpatient and inpatient service usage even after standardization, further exacerbating income-related health inequality. Conclusions: We recommend that the URRBMI design take participants’ income levels into account, with policies favoring disadvantaged individuals to enhance their medical security, improve access to healthcare services, and ultimately reduce health inequality.

To examine the longitudinal associations between sensory impairment and multimorbidity among middle-aged and older adults in China, and to explore whether activities of daily living (ADL) mediate these associations. Data were drawn from the China Health and Retirement Longitudinal Study (CHARLS), including the baseline wave in 2011 and follow-up waves in 2015 and 2018. This study was designed as a longitudinal cohort study. For repeated-measures generalized estimating equations (GEE) analysis, 11,542 participants with complete multimorbidity data across three waves were included. For longitudinal analyses of incident multimorbidity, 7,248 participants free of multimorbidity at baseline and successfully followed in both 2015 and 2018 were analyzed, accounting for 74.8% of the 9,696 participants without multimorbidity at baseline. Sensory impairment was classified into four categories using self-reported vision and hearing function: no sensory impairment (NSI), self-reported visual impairment (VI), self-reported hearing impairment (HI), and self-reported dual sensory impairment (DSI). VI was operationally defined as reporting "poor" distance or near vision, and HI as reporting "poor" hearing. Multimorbidity was defined as the presence of ≥ 2 physician-diagnosed chronic conditions. Repeated-measures logistic regression using GEE was used to examine the association between baseline sensory impairment and multimorbidity across survey waves. Fixed-time logistic regression models were further used to examine incident multimorbidity at follow-up. Multinomial logistic regression was conducted as a sensitivity analysis, and mediation analysis was conducted to examine the potential role of ADL. In the repeated-measures GEE analysis, VI, HI, and DSI were each associated with higher odds of multimorbidity across survey waves after adjustment for covariates and survey wave (VI: OR = 1.538, 95% CI: 1.426-1.658; HI: OR = 1.421, 95% CI: 1.231-1.641; DSI: OR = 2.115, 95% CI: 1.888-2.370). In fixed-time longitudinal analyses, all impairment types predicted incident multimorbidity over 2011-2015 (VI: OR = 1.381, 95% CI: 1.172-1.627; HI: OR = 1.380, 95% CI: 1.017-1.872; DSI: OR = 1.412, 95% CI: 1.063-1.875). Over the longer 2011-2018 follow-up, only DSI remained significantly associated with incident multimorbidity (OR = 1.449, 95% CI: 1.116-1.881). Multinomial logistic regression further showed a graded association between sensory impairment and chronic disease burden, with the strongest associations observed for DSI. Mediation analysis indicated that ADL partially mediated the association between DSI and incident multimorbidity, accounting for 14.20% of the total effect. Sensory impairment is significantly associated with multimorbidity among middle-aged and older Chinese adults, with DSI showing the most persistent long-term effect. ADL decline may represent a potential indirect pathway linking DSI to subsequent multimorbidity. These findings highlight the importance of integrated sensory screening and functional maintenance interventions, particularly for individuals with DSI.