Predictability of frailty index and its components on mortality in older adults in China

BACKGROUND Frailty represents an increased vulnerability to external stressors due to decreased physiological reserve and dysfunction in multiple bodily systems. The relationship between frailty and mortality has been well-documented in the literature. However, less is known about the predictive powers of frailty index and its components on mortality when they are simultaneously present. This study aimed to examine the predictive powers of frailty index and its multiple components on mortality in a nationally representative sample of older adults in China. METHODS We used a sample of 13,731 older adults from the 2008/2009 and 2011/2012 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Frailty was measured using the cumulative deficit approach, and was constructed from 38 health variables (39 deficits). We selected 8 major sets of components: activities of daily living (ADL) (6 deficits), instrumental ADL (IADL) (8 deficits), functional limitations (5 deficits), overall cognitive functioning (1 deficit), chronic disease conditions (11 deficits), self-reported health (2 deficits), hearing and vision impairment (2 deficits), and psychological distress (1 deficit). Survival analysis was used to examine the roles of the frailty and its components in mortality. RESULTS Results showed that almost all the components of the frailty index (except chronic diseases) were significant predictors of mortality when examined individually. Among the components, ADL and IADL disabilities remained significant when considering all the components simultaneously. When the frailty and its components were simultaneously analyzed, the frailty remained a robust predictor of mortality across the age and sex groups, while most components lost their significance except ADL, IADL, and cognitive function components in some cases. CONCLUSIONS Frailty measured by cumulative deficits has a stronger predictive power on mortality than its all individual components. ​ADL and IADL disability play a greater role in mortality than other components when considering all the components of frailty.