Associations of physical, psychological, and cognitive multimorbidity with health service utilisation and catastrophic health expenditure among middle-aged and older adults: a longitudinal study in China

Multimorbidity has become an increasingly pressing public health challenge in ageing societies, particularly with respect to psychological and cognitive conditions that have long been neglected. Our study describes temporal changes in patterns of physical, psychological, and cognitive multimorbidity among middle-aged and older adults in China, and examines their associations with healthcare utilisation and catastrophic health expenditure (CHE). We used data from the China Health and Retirement Longitudinal Study (CHARLS), including 11,625 participants who completed four follow-up waves from 2011 to 2018. A Sankey diagram was used to visualise the flows between multimorbidity statuses over time. Logistic regression and zero-inflated negative binomial regression models were employed to examine the associations between baseline multimorbidity and multimorbidity categories at the final wave, as well as between multimorbidity categories and healthcare utilisation and CHE. Adjustments were implemented for multiple testing. During the follow-up period, the prevalence of multimorbidity increased from 51.87% to 71.57%. Individuals with baseline single disease or multimorbidity were more likely to be classified into additional multimorbidity types at later waves. After adjusting for all covariates, individuals with physical-psychological-cognitive multimorbidity had significantly higher odds of outpatient service use (OR = 3.27; 95% CI: 2.92–3.67), inpatient service use (OR = 3.97; 95% CI: 3.45–4.57), and CHE (OR = 2.67; 95% CI: 2.37–3.02) compared with their counterparts. Our study demonstrates a rising prevalence of multimorbidity in middle-aged and older Chinese adults. Distinct multimorbidity patterns were consistently associated with greater healthcare service utilisation and increased financial burden.