To assess the association of pre-morbid functional status [Barthel Index (BI)] and frailty [modified Frailty Index (mFI)] with in-hospital mortality and a risk scoring system developed for COVID-19 in patients ≥75 years diagnosed with COVID-19.

Retrospective bicentric observational study.

Data on consecutive patients aged ≥75 years admitted with COVID-19 at 2 Italian tertiary care centers were collected from February 22 to May 30, 2020.

Overall, 221 consecutive patients with COVID-19 aged ≥75 years were admitted to 2 hospitals in the study period and were included in the analysis. Clinical, functional (BI), frailty (mFI), laboratory, and imaging data were collected. Mortality risk on admission was assessed with the COVID-19 Mortality Risk Score (COVID-19 MRS), a dedicated score developed for hospital triage.

Ninety-seven (43.9%) patients died. BI, frailty, age, dementia, respiratory rate, Pao2/Fio2 ratio, creatinine, and platelet count were associated with mortality. Analysis of the area under the receiver operating characteristic (AUC) indicated that the predictivity of age was modest and the combination of BI, mFI, and COVID-19 MRS yielded the highest prediction accuracy (AUCCOVID-19MRS+BI+mFI vs AUCAge: 0.87 vs 0.59; difference: +0.28, lower bound–upper bound: 0.17-0.34, P < .001).

Premorbid BI and mFI are associated with mortality and improved the accuracy of the COVID-19 MRS. Functional status may prove useful to guide clinical management of older individuals.