title: Factor structure for the frailty syndrome was consistent across Europe.
abstract: OBJECTIVE
  We explored the measurement properties of frailty with the goal of optimizing frailty assessment according to phenotype definition of Fried and comparing measurement properties across countries.
  
  
  METHODS
  Data are from the Survey of Health, Ageing and Retirement in Europe (n = 27,938), a population-based study of community-dwelling adults aged ≥50 years. Frailty was specified as a unidimensional construct, and measurement invariance across the 12 countries was tested. To assess our measurement model, we used confirmatory factor analysis (CFA) and multigroup CFA to assess measurement invariance.
  
  
  RESULTS
  The unidimensional model fit the data well (adjusted χ(2)(48) = 82.74, P = 0.001), and the same structure was satisfactory for all countries. Inclusion of equality constraints led to significant model deterioration (adjusted χ(2)diff(88) = 995.05, P < 0.001), suggesting differences in parameters across countries. Spain was removed from further analyses, and equality constraints for Greece, Sweden, Israel, Italy, and France were not tenable. Accounting for these led to satisfactory model fit (adjusted χ(2)(113) = 414.33, P < 0.001). Significant mean frailty differences were identified.
  
  
  CONCLUSIONS
  The relationships between the construct of frailty and indicators, although broadly constant, do vary across some countries. Furthermore, there was evidence of differing levels of frailty for the middle-aged and older populations across European countries.
authors.affiliation: Department of Medical Gerontology, Trinity College Dublin, Lincoln Gate, Dublin, Ireland. Electronic address: kingkalb@tcd.ie.
authors.forename: Bellinda L
authors.initials: BL
authors.lastname: King-Kallimanis
authors.affiliation: Department of Medical Gerontology, Trinity College Dublin, Lincoln Gate, Dublin, Ireland.
authors.forename: Rose Anne
authors.initials: RA
authors.lastname: Kenny
authors.affiliation: Department of Medical Gerontology, Trinity College Dublin, Lincoln Gate, Dublin, Ireland; School of Nursing Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom.
authors.forename: George M
authors.initials: GM
authors.lastname: Savva
mesh_terms: D000368:Aged; D005060:Europe; D005163:Factor Analysis, Statistical; D005260:Female; D016330:Frail Elderly / Q000706:statistics & numerical data*; D005853:Geriatrics / Q000379:methods*; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D007391:International Cooperation; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012179:Retirement
keywords: Confirmatory factor analysis; Cross cultural; Frailty; Measurement invariance; Older persons; Psychometric properties