Effects of intrinsic capacity on health-related outcomes are moderated by frailty status among community-dwelling older adults

Objectives To examine whether frailty moderates associations between intrinsic capacity (IC) losses and health-related outcomes among community-dwelling older adults. Design Secondary analysis of a longitudinal cohort study. Setting Community in Singapore. Participants Adults aged ≥55 years from the Individual Physical Proficiency Test for Seniors cohort. Measurements IC was assessed using the Integrated Care for Older People Step One questions, and frailty using Clinical Frailty Scale (CFS). Outcomes included ADL and iADL, Life Space Assessment, self-rated health (SRH), EQ-5D-5L, hospitalizations, A&E visits, and falls. Linear mixed and Cox proportional hazard models were used, with multiple imputation and sensitivity analyses for missing data. Results Among 1109 participants (mean age 67.7(SD 6.8) years; 73% female; 86% Chinese), 308(28%) were frail (CFS > 3). Higher cumulative IC losses were associated with iADL decline over time (IC losses × Year2 β = −0.305; 95%CI −0.50 to −0.11; p < 0.01), poorer SRH (β = −1.624; 95%CI −2.593 to −0.654; p = 0.001), lower EQ-5D-5L scores (β = −0.00689; 95%CI −0.012 to −0.001; p < 0.05), and higher hospitalization risk (HR = 1.47; 95%CI 1.08–2.01; p < 0.05). Significant IC losses × frailty interactions were observed for iADL and EQ-5D-5 L, which remained significant in imputation and sensitivity analyses. In subgroup analyses, IC losses remained associated with poorer quality-of-life measures and iADL decline among both non-frail and frail participants. Conclusion The effect of IC on health-related outcomes is influenced by frailty status. The sub-group analysis supported the detrimental effect of IC loss even among non-frail older adults. These findings support IC assessment alongside frailty evaluation.