The predictive properties of frailty-rating scales in the acute medical unit

Background: older people are at an increased risk of adverse outcomes following attendance at acute hospitals. Screening tools may help identify those most at risk. The objective of this study was to compare the predictive properties of five frailty-rating scales. Method: this was a secondary analysis of a cohort study involving participants aged 70 years and above attending two acute medical units in the East Midlands, UK. Participants were classified at baseline as frail or non-frail using five different frailty-rating scales. The ability of each scale to predict outcomes at 90 days (mortality, readmissions, institutionalisation, functional decline and a composite adverse outcome) was assessed using area under a receiver-operating characteristic curve (AUC). Results: six hundred and sixty-seven participants were studied. Frail participants according to all scales were associated with a significant increased risk of mortality [relative risk (RR) range 1.6-3.1], readmission (RR range 1.1-1.6), functional decline (RR range 1.2-2.1) and the composite adverse outcome (RR range 1.2-1.6). However, the predictive properties of the frailty-rating scales were poor, at best, for all outcomes assessed (AUC ranging from 0.44 to 0.69). Conclusion: frailty-rating scales alone are of limited use in risk stratifying older people being discharged from acute medical units.