Reliability and Validity of the Tilburg Frailty Indicator in 5 European Countries

Abstract

ObjectivesTo assess the internal consistency, convergent and divergent validity, and concurrent validity of the Tilburg Frailty Indicator (TFI) within community-dwelling older people in Spain, Greece, Croatia, the Netherlands, and the United Kingdom. DesignCross-sectional study. SettingPrimary care and community settings. ParticipantsIn total, 2250 community-dwelling older people (60.3% women; mean age = 79.7 years; standard deviation = 5.7). MethodsWe assessed the reliability and validity of the full TFI as well as its physical, psychological, and social domains. Baseline data of the Urban Health Centers Europe project were used. The internal consistency was assessed with the Cronbach alpha. The convergent and divergent validity were assessed using Pearson correlation coefficients between the domains and alternative measures: the 12-item short-form, Groningen activity restriction scale, 5-item mental well-being scale of the 36-Item Short Form Survey, and the De Jong Gierveld loneliness scale. The concurrent validity was assessed by the area under the receiver operating characteristic curve with physically frail (Survey of Health, Ageing and Retirement in Europe-Frailty Instrument), loss of independence (Groningen activity restriction scale), limited function (Global Activity Limitation Index), poor mental health (5-item mental well-being scale of the 36-Item Short Form Survey), and feeling lonely (De Jong Gierveld loneliness scale) as criteria. ResultsThe internal consistency of the full TFI was satisfactory with the Cronbach alpha ≥0.70 in the total population and in each country. The internal consistency of the psychological and social domains was not satisfactory. The convergent and divergent validity of the physical, psychological, and social domains was supported by all the alternative measures in the total population and in each country. The concurrent validity of the full TFI and the physical, psychological, and social domains was supported with most area under the receiver operating characteristic curve ≥0.70 in the total population and in each country. Conclusions and ImplicationsThe TFI is a reliable and valid instrument to assess frailty in community-dwelling older people in Spain, Greece, Croatia, the Netherlands, and the United Kingdom.