Assessing the usefulness and validity of frailty markers in critically ill adults

Rationale: Identifying frailty by the presence of a critical number of frailty markers has been difficult to operationalize in the intensive care unit (ICU), where patients often cannot complete performance measures or answer complex questions. Objectives: To assess the construct and predictive validity of a questionnaire-based approach to identifying frailty in adult ICU patients. Methods: We conducted an observational cohort study of adults admitted to a medical or surgical ICU at one of two hospitals in New York. We asked patients or surrogates about demographic information, frailty markers, and prehospital disability status. ICU physicians completed the Clinical Frailty Scale (CFS), a judgmentbased frailty assessment tool. We examined the relationship between individual frailty markers, CFS, and demographic correlates of frailty such as age, prehospital living arrangement, and prehospital disability. We assessed the predictive validity of possible frailty phenotypes, using hospital and 6-month outcomes. Results: Among 95 study participants (mean age [SD], 57.1 [17.5] yr), 80% reported one or more of seven frailty markers (median [interquartile range], 3 [1-4]). The most common frailty markers were impaired mobility (60%), impaired physical activity (60%), and decreased strength (44.2%). Patients with more frailty markers were older (mean age [SD] of those with at least three frailty markers: 62.3 [17.7] vs. 51.6 [15.8] yr; P,0.001) comparedwith those with fewer than three markers, and were more likely to be judged frail by CFS (57.0 vs. 19.6%; P = 0.001), although of the 49 patients with three or more frailty markers, CFS identified 36.7% as not frail. Malnutrition and fatigue or low energy were not significantly associated with other frailty correlates. Survivors with more frailty markersweremore likely to die or report increased disability at followup. Inmultivariatemodels, a frailty phenotype defined as at least three of the seven frailty markers performed similarly to CFS in predicting death or increased disability at 6 months (adjusted odds ratio [95% confidence interval], 3.3 [1.2-9.0] vs. 3.8 [1.2-11.7]) for CFS. Conclusions: Asking patients or surrogates about frailty markers may be a valid approach to identifying critically ill adults with a frailty phenotype associated with increased risk of adverse outcomes. Larger studies measuring frailty markers may provide insight into factors that impact short- and long-term outcomes after ICU admission.