title: Construct validity of the Groningen Frailty Indicator established in a large sample of home-dwelling elderly persons: Evidence of stability across age and gender.
abstract: BACKGROUND
  The primary objective of the present study was to evaluate the validity of the Groningen Frailty Indicator (GFI) in a sample of Dutch elderly persons participating in LifeLines, a large population-based cohort study. Additional aims were to assess differences between frail and non-frail elderly and examine which individual characteristics were associated with frailty.
  
  
  METHODS
  By December 2012, 5712 elderly persons were enrolled in LifeLines and complied with the inclusion criteria of the present study. Mann-Whitney U or Kruskal-Wallis tests were used to assess the variability of GFI-scores among elderly subgroups that differed in demographic characteristics, morbidity, obesity, and healthcare utilization. Within subgroups Kruskal-Wallis tests were also used to examine differences in GFI-scores across age groups. Multivariate logistic regression analyses were performed to assess associations between individual characteristics and frailty.
  
  
  RESULTS
  The GFI discriminated between subgroups: statistically significantly higher GFI-median scores (interquartile range) were found in e.g. males (1 [0-2]), the oldest old (2 [1-3]), in elderly who were single (1 [0-2]), with lower socio economic status (1 [0-3]), with increasing co-morbidity (2 [1-3]), who were obese (2 [1-3]), and used more healthcare (2 [1-4]). Overall age had an independent and statistically significant association with GFI scores. Compared with the non-frail, frail elderly persons experienced statistically significantly more chronic stress and more social/psychological related problems. In the multivariate logistic regression model, psychological morbidity had the strongest association with frailty.
  
  
  CONCLUSIONS
  The present study supports the construct validity of the GFI and provides an insight in the characteristics of (non)frail community-dwelling elderly persons participating in LifeLines.
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Epidemiology, Unit Health Technology Assessment, The Netherlands. Electronic address: L.L.Peters@umcg.nl.
authors.forename: L L
authors.initials: LL
authors.lastname: Peters
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Epidemiology, Section Trial Coordination Centre, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Boter
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Epidemiology, Unit Medical Statistics, The Netherlands.
authors.forename: J G M
authors.initials: JG
authors.lastname: Burgerhof
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Geriatric Medicine, The Netherlands.
authors.forename: J P J
authors.initials: JP
authors.lastname: Slaets
authors.affiliation: University of Groningen, University Medical Center Groningen, Department of Epidemiology, Unit Health Technology Assessment, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Buskens
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D016330:Frail Elderly / Q000523:psychology / Q000706:statistics & numerical data; D015577:Geriatric Assessment / Q000379:methods; D006299:Health Services for the Aged / Q000706:statistics & numerical data; D006305:Health Status Indicators; D006801:Humans; D057187:Independent Living / Q000523:psychology / Q000706:statistics & numerical data; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D010342:Patient Acceptance of Health Care / Q000523:psychology / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012107:Research Design; D012737:Sex Factors; D012959:Socioeconomic Factors
keywords: Cohort study; Construct validity; Frailty; Groningen Frailty Indicator; Measures; Morbidity; Obesity