Background The inequality caused by circumstances is known as "inequality of opportunity" (IOp). Many scholars have studied IOp in the health field, but few studies have quantified contributors to the IOp of health service utilization among middle-aged and elderly people. This study measured the IOp of health service utilization and decomposed the contributors to IOp present among Chinese middle-aged and elderly people. Methods Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS) in 2013, 2015 and 2018. A mean-based regression method was adopted to measure the IOp of health service utilization. Shapley–Shorrocks decomposition was used to analyze the main contributors to IOp seen among the middle-aged and elderly. Results Although the absolute IOp of health service utilization decreased over time, IOp still explains the total inequality to a large extent. The absolute IOp and relative IOp were greatest in the areas of self-treatment and inpatient care utilization, respectively. Shapley decomposition results showed that the out-of-pocket (OOP) ratio contributed most to the IOp of outpatient care utilization; and the residence area highly explains the IOp of inpatient service utilization. Meanwhile, social and economic factors such as work status and income contribute more to the IOp of inpatient care utilization than outpatient and self-treatment. Conclusions Strategies aimed at achieving equal opportunities remain necessary to ensure the fairness of health service utilization. Policies and measures should further adjust the medical insurance compensation policies, and pay more attention to the middle-aged and elderly residents in rural areas, optimize health resource allocation, improve the social security systems, and narrow the socioeconomic gap between urban and rural areas in China.

Medical expenses, especially among middle-aged and elderly people, have increased in China over recent decades. However, few studies have analyzed the concentration or persistence of medical expenses among Chinese residents or vulnerable groups with longitudinal survey data. Based on the data of CHARLS (China Health and Retirement Longitudinal Study), this study sought to identify characteristics associated with the concentration and persistence of medical expenses among Chinese middle-aged and elderly adults and to help alleviate medical spending and the operational risk of social medical insurance. Concentration was measured using the cumulative percentages of ranked annual medical expenses and descriptive statistics were used to define the characteristics of individuals with high medical expenses. The persistence of medical expenses and associated factors were estimated using transfer rate calculations and Heckman selection modeling. The results show that total medical expenses were concentrated among a few adults and the concentration increased over time. People in the high medical expense group were more likely to be older, live in urban areas, be less wealthy, have chronic diseases, and attend higher-ranking medical institutions. Lagged medical expenses had a persistent positive effect on current medical expenses and the effect of a one-period lag was strongest. Individuals with chronic diseases during the lagged period had a higher likelihood of experiencing persistent medical expenses. Policy efforts should focus on preventive management, more efficient care systems, improvement of serious illness insurance level, and strengthening the persistent protection effect of social medical insurance to reduce the high medical financial risk and long-term financial healthcare burden in China.

Background Medical expenses, especially among middle-aged and elderly people, have increased in China over recent decades. While the concentration and persistence of medical expenses have attracted great attention, few studies have focused on Chinese residents or vulnerable groups. This study sought to identify characteristics associated with the concentration of medical expenses and estimate their persistence among Chinese middle-aged and elderly adults. Methods Data was obtained from the China Health and Retirement Longitudinal Study, a nationally representative household survey of middle-aged and elderly adults that was conducted by the National School of Development at Peking University in 2013, 2015, and 2018. Concentration was measured using the cumulative percentages of ranked annual medical expenses and descriptive statistics were used to define the characteristics of individuals with high medical expenses. The persistence of medical expenses and associated factors were estimated using transfer rate calculations and Heckman selection modeling. Results Total medical expenses were concentrated among a few middle-aged and elderly adults and the concentration increased over time. Compared with middle-aged and elderly adults in the lower 90% medical expense group, those in the top 10% high medical expense group were more likely to be older, live in urban areas, be less wealthy, have chronic diseases, and attend higher-ranking medical institutions. High medical expenses demonstrated strong persistence. Lagged medical expenses had a persistent positive effect on the incidence and volume of current medical expenses and the effect of a one-period lag was strongest. Individuals with chronic diseases during the lagged period had a higher likelihood of experiencing persistent medical expenses. Factors such as age ≥75 years, income, health insurance, comorbidities, and receiving a higher number of medical services were significant positive contributors to higher medical expenses. Conclusion Policy efforts should focus on preventive management and optimizing the allocation of health resources to reduce high medical expenses and inequitable access to health services among middle-aged and elderly individuals in China. The government should establish a more efficient care system and adjust social health insurance policies to alleviate the long-term financial healthcare burden.

Background: The inequality caused by circumstances is known as "inequality of opportunity" (IOp). Many scholars have studied IOp in the health field, but few studies have quantified contributors to the IOp of health service utilization among middle-aged and elderly people. This study measured the IOp of health service utilization and decomposed the contributors to IOp present among Chinese middle-aged and elderly people.Methods: Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS) in 2013, 2015 and 2018. A mean-based regression method was adopted to measure the IOp of health service utilization. Shapley–Shorrocks decomposition was used to analyze the main contributors to IOp seen among the middle-aged and elderly.Results: Although the absolute IOp of health service utilization decreased over time, the inequality due to circumstance factors still accounted for a large part of the total inequality. The absolute IOp and relative IOp were greatest in the areas of self-treatment and inpatient care utilization, respectively. The IOp of health service utilization in urban areas was greater than that in rural areas, and the heterogeneity between urban and rural areas was more prominent in the area of inpatient care utilization. The out-of-pocket (OOP) ratio contributed most significantly to the IOp of outpatient care utilization; meanwhile, work status and income had a great impact on the IOp of inpatient care utilization. Among urban-dwelling middle-aged and elderly individuals, apart from the OOP ratio, work status largely explained the IOp of outpatient care and self-treatment utilization, while distance greatly explained the IOp of outpatient care utilization in rural areas. Work status, education, and income level contributed more to the IOp of inpatient care utilization in rural areas than in urban areas.Conclusions: Strategies aimed at achieving equal opportunities remain necessary to ensure the fairness of health service utilization. Policy measures should pay more attention to middle-aged and elderly residents of rural areas, and efforts should be made to further optimize health resource allocation, improve social security systems, and narrow the socioeconomic gap between urban and rural areas in China.