Clinical frailty as a key characteristic of the patient population of the NHS Nightingale North West COVID-19 temporary emergency field hospital: cohort study April to June 2020.

A total of 104 COVID-19 patients were admitted, 74% with moderate-to-severe frailty (clinical frailty score, CFS > 5). A total of 84 were discharged, 14 transferred to other hospitals, and six died on site. High C-reactive protein (CRP) > 50 mg/dL predicted 30-day mortality (adjusted odds ratio 11.9, 95%CI 3.2-51.5,  < 0.001). Patients with CFS > 5 had a 10-day median admission, versus 7-day for CFS ≤ 5 and half the likelihood of discharge on a given day (adjusted hazard ratio 0.51, 95%CI 0.29-0.92,   =  0.024). CRP > 50 mg/dL and hospital-associated COVID-19 also predicted admission duration. As more frail patients had a lower rate of discharge, prevalence of CFS > 5 increased from 64% initially to 90% in the final week (non-zero slope  < 0.001). The NNW population was characterized by high levels of frailty, which increased over the course of the hospital's operation, with subsequent operational implications. Identifying and responding to the needs of this population, and acknowledging the risks of this unusual clinical context, helped the hospital to keep patients safe.