Sex differences in the relative heterogeneity of frailty in relation to age, frailty, health protection, and five-year mortality

Abstract

Background: Previous studies have suggested that the relative heterogeneity of frailty declines with increases in age and the level of the frailty index (FI). In this study, we investigated the sex difference in the relative heterogeneity of frailty and its response to health-protective factors, in a Chinese community sample. Methods: Data used for this secondary analysis were obtained from the Beijing Longitudinal Study of Aging that involved 3257 community-dwelling Chinese people aged 55 years and older at baseline. An FI was constructed for each indicial using 35 variables assessing health-related problems. A protection index (PI) consisting of 27 variables assessing lifestyle and social engagement was also built. The relative heterogeneity of frailty, as measured by the coefficient of variation (CV) of the FI, was calculated as the ratio of the standard deviation to the mean FI for different age, FI, and PI groups, and for the five-year survival status. Results: The CV decreased with the increase in age (F = 20.60, P =.006) and the FI (F = 57.59, P =.001), consistent in both sexes. In each age group, the CV was higher in men than in women (t = 3.25, P =.018). A great level of protection was associated with a significantly reduced mortality, and an increased CV (t = 2.91, P =.027). Conclusions: Our data demonstrate that a gender difference exists in the relative heterogeneity of frailty, which is negatively related to age and frailty as well as positively associated with health protection and the five-year survival.