The cost of end-of-life care is an important topic in health and wellness sector. There are few studies focus on the end-of-life medical expenditures of older adults in China, especially the causes of urban-rural differences in end-of-life medical expenditures in this population.

To investigate the associated factors of medical expenditures of Chinese oldest old population (≥80 years) in the year before their death, and to analyze rural-urban differences in the medical expenditures as well as their causes.

In September 2021, 1 399 oldest-old adults who died in 2014—2018 with full data of medical expenditure and other key variables in the year prior to their death were selected from the participants of Chinese Longitudinal Healthy Longevity Survey 2018. Ordinary least squares regression was used to analyze the associated factors of the medical expenditures. The Oaxaca-Blinder technique was used to decompose urban-rural differences in the expenditures.

The median medical expenses of the participants in the year prior to their death was 3 500.00 yuan, and the interquartile range was 9 000.00 yuan, the logarithmic mean value was (8.09±1.73) yuan. The residence, age at death, gender, marital status, living arrangement, prevalence of disability, prevalence of endowment insurance, place of death, accessibility of medical services, prevalence of being confined to bed, and annual household income per capita were factors associated with the medical expenditures in the year prior to death (P<0.05). After controlling for confounding factors, the medical expenses of the urban participants in the year prior to their death was 42.6% higher than that of participants living in rural areas. According to the findings of Oaxaca-Blinder decomposition, the explainable and unexplainable parts of the urban-rural differences accounted for 32.86% and 67.14%, respectively. Of the explainable part, 18.70% was caused by differences in endowment insurance participation, 30.18% by differences in place of death, and 40.42% by differences in annual household income per capita.

The medical expenditures in the year prior to death in the oldest-old were associated with complex factors, and showed large urban-rural differences. It is essential that efforts should be made to implement healthy aging strategies, balance the allocation of urban and rural medical resources, improve social security system for older adults, and to develop end-of-life care. All of these will help reduce the medical expenditures and improve the quality of life and death of older adults at the end of their life.