Concurrent and Predictive Validity of FRAIL-NH in Hospitalized Older Persons: An Exploratory Study

The FRAIL-NH was originally developed for frailty assessment of nursing home (NH) residents. We aimed to compare concurrent, predictive, and known-groups validity between FRAIL-NH and FRAIL, using the Frailty Index (FI) as gold standard reference. We also examined for ceiling effect of both measures in the detection of severe frailty.

A secondary analysis of a prospective cohort study.

Older adults (mean age 89.4 years) hospitalized for an acute medical illness in a 1300-bed tertiary hospital.

Baseline data on demographics, comorbidities, severity of illness, functional status, and cognitive status were gathered. We also captured outcomes of mortality, length of stay (LOS), institutionalization, and functional decline. For concurrent validity, we compared areas under the operating characteristic curves (AUCs) for both measures against the FI. For predictive validity, univariate analyses and multiple logistic regression were used to compare both measures against the adverse outcomes of interest. For known-groups validity, we compared both measures against comorbidities and functional status via 1-way analysis of variance, and dementia diagnosis via independent t test. Box plots were also derived to investigate for possible ceiling effect.

Both measures had good concurrent validity (both AUC > 0.8 and P < .001), with FRAIL-NH detecting more frailty cases (79.5% vs 50.0%). Although FRAIL-frail was superior for in-hospital mortality [6.7% vs 1.0%, P = .031, odds ratio (OR) 9.29, 95% confidence interval (CI) 1.09-79.20, P < .042] and LOS (10 vs 8 days, P = .043), FRAIL-NH-frail better predicted mortality (OR 6.62, 95% CI 1.91-22.94, P = .003) and institutionalization (OR 6.03, 95% CI 2.01-18.09, P = .001) up to 12 months postenrollment. Known-groups validity was good for both measures with FRAIL-NH yielding greater F values for functional status and dementia. Lastly, box plots revealed a ceiling effect for FRAIL in the severely frail group.

This exploratory study highlights the potential for expanding the role of FRAIL-NH beyond NH to acute care settings. Contrasted to FRAIL, FRAIL-NH had better overall validity with less ceiling effect in discrimination of severe frailty.