68 DEVELOPMENT OF AN IRISH HIP FRACTURE DATABASE FRAILTY INDEX: ASSOCIATIONS WITH LENGTH OF STAY, DELIRIUM, MORTALITY AND NURSING HOME ADMISSION

Abstract

Abstract Background In older people, hip fracture can lead to adverse outcomes. Frailty, capturing biological age and vulnerability to stressors, can indicate those at higher risk. This study aimed to derive a frailty index (FI) in the Irish Hip Fracture Database (IHFD), to explore associations with prolonged length of hospital stay (LOS ≥ 30 days), delirium, inpatient mortality and new nursing home (NH) admission and to assess whether the FI added value to those predictions above and beyond age, sex, and pre-operative American Society of Anaesthesiology (ASA) score. Methods A 21-item FI was constructed with 16 dichotomous comorbidities, three 4-level ordinal pre-morbid functional variables (difficulty with indoor mobility, outdoor mobility, and shopping), and nursing home provenance (yes/no). The FI was computed as the proportion of items present, and divided into tertiles (low, medium, high risk). Independent associations between FI and outcomes were explored with logistic regression, from which we extracted adjusted Odds Ratios (aOR) and areas under the curve (AUC). Results From 2017-2020, the IHFD included 14,615 hip fracture admissions, mean (SD) age 80.4 (8.8), 68.9% women. Complete FI data was available for 12,502 (85.5%). By FI tertile (low to high risk), prolonged LOS proportions were 5.9%, 16.1% and 23.1%; delirium 5.5%, 13.5% and 17.6%; inpatient mortality 0.6%, 3.3% and 10.1%; and new nursing home admission 2.2%, 5.9% and 11.3%. All associations were statistically significant (p<0.001) independently of age and sex. AUC analyses suggested that the FI score, added to age, sex, and ASA score, added value to the prediction of delirium and new NH admission (p<0.05), and especially to prolonged LOS and inpatient mortality (p<0.001). Conclusion A 21-item FI in the IHFD was a significant predictor of outcomes and added value to traditional risk markers. The utility of a routinely derived FI to more efficiently direct limited orthogeriatric resources requires further investigation.