Background: It is a well-described clinical phenomenon that females live longer than males, yet tend to experience greater levels of co-morbidity and disability. Females can therefore be considered both more frail (because they have poorer health status) and less frail (because they have a lower risk of mortality). This systematic review aimed to determine whether this ageing paradox is demonstrated when the Frailty Index (FI) is used to measure frailty.
Methods: Medline, EMBASE and CINAHL databases were searched for observational studies that measured FI and mortality in community-dwellers over 65years of age. In five-year age groups, meta-analysis determined the sex differences in mean FI (MD=mean FIfemale-mean FImale) and mortality rate.
Results: Of 6482 articles screened, seven articles were included. Meta-analysis of data from five studies (37,426 participants) found that MD values were positive (p<0.001; MD range=0.02-0.06) in all age groups, indicating that females had higher FI scores than males at all ages. This finding was consistent across individual studies. Heterogeneity was high (I2=72.7%), reflecting methodological differences. Meta-analysis of mortality data (13,127 participants) showed that male mortality rates exceeded female mortality rates up until the 90 to 94-years age group. Individual studies reported higher mortality for males at each level of FI, and higher risk of death for males when controlling for age and FI.
Conclusions: The pattern of sex differences in the FI and mortality of older adults was consistent across populations and confirmed a 'male-female health-survival paradox'.
Keywords: Frailty; Frailty Index; Meta-analysis; Sex differences; Systematic review.
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