Impact of an Outpatient Coverage Scheme on Health-care Utilization Among Middle-Aged and Older Adults: Evidence from the Outpatient Mutual-Aid Security Policy in China

China's social medical insurance system has long focused on reducing the risk of catastrophic health expenditures from serious illnesses, overlooking the economic burden of common diseases brought by population aging. To address this problem, China implemented the outpatient mutual-aid security (OMAS) policy for covering outpatient services under its basic medical insurance system for the employed. Using panel data from the China Health and Retirement Longitudinal Study between 2011 and 2018, this study aimed to investigate whether the OMAS policy changed the middle-aged and older adults' utilization pattern of health services by utilizing the difference-in-differences (DID) approach. The results indicated that the implementation of the OMAS policy increased the number of outpatient visits (Coefficient = 0.240, <i>p</i> < .05) and reduced the number of inpatient visits (Coefficient = -0.117, <i>p</i> < .05) without increasing financial risk among middle-aged and older adults. The OMAS policy was also found to be associated with improvements in self-rated health (Coefficient = 0.234, <i>p</i> < .05) and a reduction in the number of ADL limitations (Coefficient = -0.103, <i>p</i> < .05) over the course of its extended implementation. Our study demonstrated that the OMAS policy has led to changes in health-care utilization patterns and enhancements in health outcomes in the long term.