Ruth Hubbard

Background Frailty is an important determinant of health‐care needs and outcomes for people in hospital. Objectives To compare characteristics and predictive ability of a multidomain frailty index derived from routine health data (electronic frailty index‐acute hospital; eFI‐AH) with the hospital frailty risk score (HFRS). Methods This retrospective study included 6771 patients aged ≥75 years admitted to an Australian metropolitan tertiary referral hospital between October 2019 and September 2020. The eFI‐AH and the HFRS were calculated for each patient and compared with respect to characteristics, agreement, association with age and ability to predict outcomes. Results Median eFI‐AH was 0.17 (range 0–0.66) whilst median HFRS was 3.2 (range 0–42.9). Moderate agreement was shown between the tools (Pearson's r 0.61). After adjusting for age and gender, both models had associations with long hospital stay, in‐hospital mortality, unplanned all‐cause readmission and fall‐related readmission. Specifically, the eFI‐AH had the strongest association with in‐hospital mortality (adjusted odds ratio (aOR) 2.81, 95% confidence intervals (CI) 2.49–3.17), whilst the HFRS was most strongly associated with long hospital stay (aOR 1.20, 95% CI 1.18–1.21). Both tools predicted hospital stay >10 days with good discrimination and calibration. Conclusions Although the eFI‐AH and the HFRS did not consistently identify the same inpatients as frail, both were associated with adverse outcomes and they had comparable predictive ability for prolonged hospitalisation. These two constructs of frailty may have different implications for clinical practice and health service provision and planning.