Intrinsic Capacity and Multimorbidity Predicting Incident Disability - Insights from the I-Lan Longitudinal Aging Study

Objectives: This longitudinal cohort study aimed to examine the effect of intrinsic capacity (IC) and multimorbidity on the development of new disabilities. Methods: The study utilized data from 1,009 participants without disabilities from the I-Lan Longitudinal Aging Study. Multivariable logistic regressions were employed to assess the predictive capability of IC (ranging from 0 to 100) and multimorbidity for incident disability over a 7-year follow-up period. Results: Both low IC (OR 4.9, 95% CI 2.1-11.1, p<0.001) and multimorbidity (OR 4.5, 95% CI 2.2-9.2, p<0.001) significantly predicted incident disability over the 7-year period. A one-point increase in IC reduced the risk of incident disability by 10% (OR 0.9, 95% CI 0.8-0.9, p<0.001). Among IC subdomains, both better locomotion (OR 0.96, 95% CI 0.94-0.99, p=0.014) and psychology (OR 0.97, 95%CI 0.94-1.00, p=0.049) significantly reduced the risk of incident disability. Rapid declines in IC significantly predicted incident disability (OR 4.1, 95% CI 1.8-9.3, p=0.001), whereas the onset of new multimorbidity or changes in the number of chronic conditions did not demonstrate a significant association with incident disability. The interaction terms between IC and multimorbidity, both categorically (low IC * multimorbidity, p=0.959) and numerically (IC (per point) * multimorbidity, p=0.660) were all statistically insignificant. Conclusions: IC exhibited better predictive capacity for 7-year incident disability compared to multimorbidity, so health care services targeting older adults should adopt an integrated care approach that combines both function- and disease-centric strategies.