Frailty score before admission as risk factor for mortality of renal patients during the first wave of the COVID pandemic in London

Background: Frailty is a known predictor of mortality and poor outcomes during hospital admission. In this large renal retrospective cohort study, we investigated whether frailer COVID-19 positive renal patients had worse outcomes. Design: All SARS-Cov-2 positive renal patients aged ≥18 years who presented to the emergency department at the Royal Free Hospital or at the satellite dialysis centres from 10th of March until the 10th of May 2020, with recent data on frailty, were included. The follow up was until 26th of May 2020. Age, gender, ethnicity, body mass index, chronic kidney disease stage, modality of renal replacement therapy, co-morbidities, Rockwood clinical frailty score (CFS), C reactive protein and the neutrophil-to-lymphocyte count were collected at presentation. The primary outcome was the overall mortality rate following COVID-19 diagnosis. Secondary outcomes included the need for hospital admission. Results: A total of 200 renal patients were SARS-Cov-2 positive. In the 174 patients who had a CFS recorded, the age was 65.4 years ± 15.8 (mean ± SD) and 57,5% were male. At the end of follow up, 26% had died. Frail patients (CFS 5-7) were more than three times more likely to die compared to less frail patients (CFS of 1-4) (odds ratio (OR) 3.3, 95% confidence interval (CI) 1.0-10.6). 118 patients (68%) required admission, but there was no difference in hospital admission rates for frail vs non-frail patients (OR 0.6, CI 0.3-1.7). Conclusions: Frailty is a better predictor of mortality than age and co-morbidities in COVID-19 positive renal patients.