The bidirectional relationship between intrinsic capacity and catastrophic health expenditure in China: A Longitudinal Study

Background: Intrinsic capacity (IC), as a potential proxy for healthy ageing, guidance on framing the concept is limited. Furthermore, research on the relationship between IC and catastrophic health expenditure (CHE) is scarce.The current study aims to construct a validated IC framework using structural equation modelling (SEM) and examine such an association among older adults in China.

Methods: Using a 4-year prospective observational study, we enrolled 5,427 participants from wave 1 and wave 3 in the China Health and Retirement Longitudinal Study (CHARLS) for analysis. The SEM was used to construct IC score, and assessed its association with medical and financial burdens by using negative binomial regression and logistic mixed-effect models, where financial burden was defined as CHE according to the World Bank definitions.

Results: The SEM results showed a clear 5-subfactor structure for IC. After adjustment for potential confounders, the populations with poor and moderate IC had 1.927 times [95% confidence intervals (95% CI): 1.559-2.382] and 1.548 times (95% CI: 1.281-1.872) higher risk for inpatient visits in comparison with the group showing high IC, respectively, and also experiencing 2.163 times (95% CI: 1.674-2.795) and 1.687 times (95% CI: 1.347-2.112) risk for CHE, respectively.

Conclusions: Our analysis with both cross-sectional and longitudinal representative national data, provided an extensive picture of the adverse effects of IC loss, demonstrating that a favorable IC is important to reduce medical and financial burden. IC is applicable to more widely as a usual clinical assessment tool to reduce effectively health burden.