Background and aims: Relatively little is known about how region of residence influences frailty of seniors. Frailty indexes can be used to investigate these effects. We constructed and validated a frailty index, to investigate the differences in health status between rural and urban seniors.
Methods: We studied rural (n=949) and urban (n=7598) older adults in the Canadian Study of Health and Aging, of whom 22% died over 72 months. The frailty index was generated from 40 self-reported health deficits (symptoms, diseases, disabilities, unfavourable living conditions).
Results: The average value of the frailty index increased exponentially with age in both groups (rural: r=0.94; urban: r=0.97, p<0.01) and was highly correlated with mortality (r=0.96 for rural, r=0.97 for urban, p<0.01). Up to age 80, there were few rural-urban differences in frailty. After age 80, the rural sample showed higher mortality than the urban sample. The hazard ratio for death for each increment in the frailty index was 1.38 (1.14-1.72) in rural participants vs 1.18 (1.11-1.26) in urban participants. Women lived longer than men at any index value.
Conclusions: Frailty index analysis readily summarizes health and mortality differences between very old rural and urban dwellers, which reflect differences in deficit accumulation, and in the impact of gender on survival. The frailty index provides efficient dimensionality reduction for studying group differences in the health of older adults.