Cumulative social disadvantage and inequitable utilisation of healthcare and long-term care services among older adults with complex needs: a cross-sectional study in China

Background: Older adults with complex needs (CNs) exhibit substantial demands for healthcare and long-term care (LTC) services. Although social disadvantage markedly impairs access to services, empirical research on this population remains sparse, and key dimensions remain unexplored. While LTC services can influence healthcare service utilisation, evidence regarding their role in the association between social disadvantage and healthcare service utilisation among this population remains limited. Methods: We conducted a cross-sectional study using data from the Long-Term Care Insurance of Shanghai, China, from January to June 2023. We combined five domains of social disadvantage into a cumulative score and categorised it into quintiles. Negative binomial regression models evaluated associations between cumulative social disadvantage (including its quintiles) and its individual dimensions and utilisation of healthcare and LTC services. A parallel multiple mediation analysis examined the mediating roles of formal and informal care between cumulative social disadvantage and healthcare service utilisation. Results: Among 42,499 CN older adults, increasing cumulative social disadvantage was associated with graded reductions in the utilisation of healthcare and LTC services. Educational disadvantage and healthcare access disadvantage exhibited the strongest negative associations with care service utilisation. We observed significant additive interactions between these two disadvantages for outpatient visit frequency (relative excess risk due to interaction (RERI) = 0.093), hospital stay duration (RERI = 0.576), formal care frequency (RERI = 0.191), and informal care frequency (RERI = 0.379). Although LTC services statistically mediated the association between cumulative social disadvantage and healthcare service utilisation, the proportion mediated remained below 1%. Conclusions: Cumulative social disadvantage was significantly correlated with reduced utilisation of healthcare and LTC services among CN older adults. Policymakers should pay close attention to the social disadvantages experienced by CN older adults, focusing on healthcare access and educational attainment, while working to increase outpatient visit utilisation. Furthermore, fostering the synergistic development of healthcare and LTC services is essential.