Intrinsic capacity differs from functional ability in predicting 10-year mortality and biological features in healthy aging: results from the I-Lan longitudinal aging study
Aging (Albany NY). Wei-Ju Lee et al.
This study aimed to explore the biological features and mortality risk of intrinsic capacity (IC) and functional ability (FA). Based on data from 1839 participants from the I-Lan Longitudinal Aging Study, multivariable Cox proportional hazard models were used to evaluate the predictive ability of IC (range 0-100) and FA (range 0-100) on 10-year mortality. Of 2038 repeated measurements for IC within a 7-year observational period, multivariable logistic regression was used to compare biological features of participants with maintained, improved and rapidly deteriorated IC. A 1-point increased IC value was associated with a 5% (HR 0.95, 95% CI 0.93-0.97, p < 0.001) decrease in mortality risk. Low IC (HR 1.94, 95% CI 1.39-2.70, p < 0.001) was associated with higher mortality risk. Hyperglycemia (OR 1.40, 95% CI 1.09-1.81, p = 0.010), low serum levels of DHEA-S (OR 3.33, 95% CI 1.32-8.41, p = 0.011), and high serum levels of C-reactive protein (OR 1.45, 95% CI 1.05-2.00, p = 0.023) were associated with low IC at baseline. Low serum levels of DHEA-S (middle tertile OR 1.84, 95% CI 1.15-2.95, p = 0.012; lowest tertile OR 2.25, 95% CI 1.34-3.77, p = 0.002) and vitamin D deficiency (OR 1.82, 95% CI 1.02-3.27, p = 0.044) were associated with rapid deterioration of IC. IC and FA predicted 10-year mortality, whereas chronic inflammation, hyperglycemia, and low DHEA-S were associated with low IC status. Low DHEA-S and vitamin D deficiency may be considered as potential biomarkers of rapid IC declines, which implies underlying biological mechanisms of healthy aging.