Intrinsic capacity and 10-year mortality: Findings from a cohort of older people

Abstract

Background and objectives: Longitudinal data with regard to the association between intrinsic capacity (IC) and mortality is required for prevention efforts. We examined the association between IC and 10-year mortality among older people.

Research design and methods: We recruited a cohort of 2032 Chinese people aged 70 years and older, 1371 of them could be traced over follow-up, of which 1096 died within 10 years. Of those who were traceable, 846 were complete cases regarding the data for the exposure, outcome and covariates. Multiple imputation was used to handle missing data. Nine indicators were included to represent the construct of IC. All-cause mortality was collected from the Death Registry. Multivariable Cox proportional hazard regression model and Kaplan-Meier estimator were used to assess the association between IC and mortality.

Results: The mean age of the 2032 participants was 79.7 years and 51 % were female. Compared with those in the lowest (best) quartile of IC, those in the highest (worst) quartile were associated with 1.48-fold (95 % CI 1.21-1.82) higher risk of mortality, after adjustment for sociodemographic variables. When past medical illnesses were further adjusted, the hazard ratio was attenuated (1.41; 95 % CI 1.15-1.73). Kaplan-Meier estimator for survival probability similarly showed a graded mortality pattern. The association between IC and mortality remained similar when the analysis was confined to community-dwelling older people.

Discussion and implications: IC is associated with mortality in a dose-response fashion. Assessment of IC should be instituted in community and institutional settings to enable formulation of early interventions.

Keywords: Biological age; Healthy ageing; Intrinsic capacity; Mortality; Survival.