ABSTRACTBackgroundOlder adults with coronavirus disease 2019 (COVID-19) face an increased risk of adverse health outcomes including mortality. Ethical guidelines consider allocation of limited resources based on likelihood of survival, frilty, co-morbidities and age. However, the association of frailty with clinical outcomes in older COVID-19 patients remains unclear.ObjectivesTo determine the association between frailty and short-term mortality in older adults hospitalized for COVID-19.DesignRetrospective single-center observational study.Setting and participantsN = 81 patients with COVID-19 confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR), at the Geriatrics department of Imelda general hospital, Belgium.MeasurementsFrailty was graded according to the Rockwood Clinical Frailty Scale (CFS). Demographic, biochemical and radiological variables, co-morbidities, symptoms and treatment were extracted from electronic medical records.ResultsParticipants (N = 48 women, 59%) had a median age of 85 years (range 65-97 years), median CFS score of 7 (range 2 - 9), and 42 (52%) were long-term care residents. Within six weeks, eighteen patients died. Mortality was significantly but weakly associated with age (Spearman r = 0.241, P = 0.03) and CFS score (r = 0.282, P = 0.011), baseline lactate dehydrogenase (LDH) (r = 0.301, P = 0.009), lymphocyte count (r = -0.262, P = 0.02) and RT-PCR Ct value (r = -0.285, P = 0.015). Mortality was not associated with long-term care residence, dementia, delirium or polypharmacy. In multivariable logistic regression analyses, CFS, LDH and RT-PCR Ct values (but not age) remained independently associated with mortality. Both age and frailty had poor specificity to predict survival. A multivariable model combining age, CFS, LDH and viral load significantly predicted survival.Conclusions and implicationsAlthough their prognosis is worse, even the oldest and most severely frail patients may benefit from hospitalization for COVID-19, if sufficient resources are available.BRIEF SUMMARYOutcomes of frail older adults hospitalized for COVID-19, particularly long-term care residents, remain unclear. In this retrospective cohort, frailty predicted mortality independently of age or established biomarkers.