The Italian version of the “frailty index” based on deficits in health: a validation study

BACKGROUND AND AIM: Several measurements were taken for frailty classification in geriatric population. "Frailty index" is based on "deficits in health," but it is still not available in Italian version. Thus, the aim of the present work was to validate a version of "frailty index" for the Italian geriatric community. METHODS: The validation of Italian frailty index (IFi) is based on a cohort study that enrolled 1077 non-disabled outpatients aged 65 years or older (81.3 ± 6.5 years) in Naples (Italy). IFi has been expressed as a ratio of deficits present/deficits considered after a comprehensive geriatric assessment. IFi was stratified in light, moderate and severe frailty. Mortality, disability (considering an increase in ADL lost ≥1 from the baseline) and hospitalization were considered at 3, 6, 12, 18 and 24 months of follow-up. Area under curve (AUC) was evaluated for both Fried's and IFi frailty index. RESULT: At the end of follow-up, mortality increased from 1.0 to 30.3%, disability from 40.9 to 92.3% and hospitalization from 0.0 to 59.0% (p < 0.001 for trend). Multivariate analysis shows that the relative risk for unit increase in IFi is 1.09 (95% CI = 1.01-1.17, p = 0.013) for mortality, 1.04 (95% CI = 1.01-1.06, p = 0.024) for disability and 1.03 (95% CI = 1.01-1.07, p = 0.041) for hospitalization. AUC is higher in IFi with respect to Fried's frailty index when considering mortality (0.809 vs. 0.658, respectively), disability (0.800 vs. 0.729, respectively) and hospitalization (0.707 vs. 0.646, respectively). CONCLUSIONS: IFi is a valid measure of frailty after the comprehensive geriatric assessment in an Italian cohort of non-institutionalized patients.