The physical phenotype of frailty for risk stratification of older medical inpatients.

Objectives: To determine the usefulness of physical phenotype of frailty, cognitive impairment, and serum albumin for risk stratification of elderly medical impatients.

Design: Prospective, observational cohort study.

Setting: A general internal medicine unit of a university hospital in Italy.

Participants: Inpatients with an average age of 80.8 ± 7.5 yr (N = 470).

Measurements: Frailty was defined using the Study of Osteoporotic Fractures Index, a parsimonious version of the physical phenotype (two of the following markers: weight loss, inability to rise five times from a chair, and exhaustion). Two frailty markers from non-physical dimensions were also evaluated: cognitive impairment (Mini-Cog score < 3) and low serum albumin on ward admission (< 3,5 gr/dl). Logistic regression adjusted for preadmission and admission-related confounders was used to investigate whether the physical phenotype of frailty and the two non-physical markers were associated with ward length of stay and unfavorable discharge (death plus any other ward discharge disposition different from direct return home). Areas Under the receiver operating characteristic Curve (AUCs) and Likelihood Ratios (LRs) were used for evaluation of discriminatory ability and clinical usefulness of significant predictors.

Results: The physical phenotype of frailty was associated with both study outcomes (p < 0.010) but the association was mainly mediated by chair standing ability. Non-physical markers were associated only with unfavourable discharge (p < 0.001). All of these predictors, either alone or in combination, had poor discriminatory ability (AUCs < 0.70) and poor clinical usefulness (+LRs near 1) for the study outcomes.

Conclusions: The physical phenotype of frailty appears of limited clinical use for risk stratification of older medical inpatients. Combination with markers from non-physical dimensions does not improve its prognostic abilities.