title: Sex differences in frailty: A systematic review and meta-analysis.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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'.
authors.affiliation: School of Medicine, The University of Queensland, Brisbane, QLD, Australia. Electronic address: e.gordon@uq.edu.au.
authors.forename: E H
authors.initials: EH
authors.lastname: Gordon
authors.affiliation: Centre for Research in Geriatric Medicine, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: N M
authors.initials: NM
authors.lastname: Peel
authors.affiliation: QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Samanta
authors.affiliation: Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: O
authors.initials: O
authors.lastname: Theou
authors.affiliation: Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: S E
authors.initials: SE
authors.lastname: Howlett
authors.affiliation: Centre for Research in Geriatric Medicine, The University of Queensland, Brisbane, QLD, Australia.
authors.forename: R E
authors.initials: RE
authors.lastname: Hubbard
mesh_terms: D000368:Aged; D000375:Aging; D015897:Comorbidity; D004185:Disability Evaluation; D005260:Female; D016330:Frail Elderly / Q000706:statistics & numerical data*; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D009026:Mortality; D012727:Sex Characteristics
keywords: Frailty; Frailty Index; Meta-analysis; Sex differences; Systematic review