Measurement properties of the Groningen Frailty Indicator in home-dwelling and institutionalized elderly people.

OBJECTIVES To enable prevention of poor outcome in elderly people, a valid instrument is required to detect individuals at high risk. The concept of frailty is a better predictor than age alone. The Groningen Frailty Indicator (GFI) has been developed to identify frailty. We assessed feasibility, reliability, and construct validity of the self-assessment version of the GFI. DESIGN Cross-sectional. SETTING Community-based. PARTICIPANTS Home-dwelling and institutionalized elderly persons were included in the study (n = 353) who met the following inclusion criteria: persons 65 years and older who were able to fill out questionnaires. MEASUREMENTS The feasibility of the GFI was assessed by determining the proportion of missing values per item. The internal consistency reliability of the GFI was established by calculating the KR-20. Mann-Whitney and Kruskal-Wallis tests were applied to assess discrimination between specific subgroups (known group validity). Convergent and discriminant validity was assessed using Spearman Rank correlations between GFI and diseases and disorders, case complexity, and health care needs (INTERMED), life satisfaction (Cantril Ladder of Life), activities of daily living (Katz), quality of life (EQ-5D), and mental health (SF-36). Finally, we used multivariate regression analyses to evaluate the cutoff score of the GFI (<4 versus ≥4). RESULTS A total of 296 (84%) of the participants completed all items of the GFI; the internal consistency was 0.68. The GFI yielded statistically significant GFI scores for subgroups (known group validity). The correlations for the convergent (range 0.45 to 0.61) and discriminant validity (range 0.08 to 0.50) were also as hypothesized. In contrast with nonfrail participants, frail older persons had higher levels of case complexity, disability, and lower quality of life and life satisfaction. CONCLUSIONS This study supports the feasibility, reliability, and validity of the self-assessment version of the GFI in home-dwelling and institutionalized elderly people.