Predicting outcome after hip fracture: using a frailty index to integrate comprehensive geriatric assessment results

INTRODUCTION: hip fracture is expensive in terms of mortality, hospital length of stay (LOS) and consequences for independence. Poor outcome reflects the vulnerability of patients who typically sustain this injury, but the impact of different comorbidities and impairments is complex to understand. We consider this in a prospective cohort study designed to examine how a patients' frailty index (FI) predicts outcome. METHODOLOGY: consecutive patients with low trauma hip fracture were assessed, excluding only those unfit for surgery. Comprehensive Geriatric Assessment (CGA) findings were used to derive a FI for each patient, which was examined alongside other assessment and outcome data from our National Hip Fracture Database (NHFD) submission for these individuals. RESULTS: we describe 178 patients; mean age 81 years, 73.5% female. The mean FI was 0.34 (SD = 0.16), and logistic regression identified abbreviated mental test score and FI as the strongest predictors of poor outcome. When patients were stratified by FI, 56 (31.5%) were in the low-frailty group (FI ≤0.25), 58 (32.5%) in intermediate (FI >0.25-0.4), and 64 (36%) in the high-FI group (FI >0.4). All the patients in the low-FI group returned to their original residence within a mean of 21.6 days. The mean LOS for the intermediate group was 36.3 days compared with 67.8 days in the high-FI group (P < 0.01) while 30-day mortality was 3.4% for the intermediate group compared with 17.2% for the high-FI group (P < 0.001). CONCLUSIONS: individual CGA findings proved disappointing as outcome predictors, while FI turned out to be a better predictor of mortality, 30-day residence and length of inpatient stay.