The National Early Warning Score (NEWS2) systematically underestimates the risk of in-hospital mortality in unplanned COVID-19 admissions to hospital.

Richardson, D.; Faisal, M.; Fiori, M.; Beatson, K.; A Mohammed, M.

Background: Although the National Early Warning Score (NEWS) and its latest version NEWS2 are recommended for monitoring for deterioration in patients admitted to hospital, little is known about their performance in COVID-19 patients. We analysed the performance of National Early Warning Score (NEWS2) during the first phase of the COVID-19 pandemic. Methods: Adult non-elective admissions discharged between 11-March-2020 to 13-June-2020 with an index NEWS2 electronically recorded within 24 hours of admission are used to predict mortality at four time points (in-hospital, 24hours, 48hours, and 72hours) in COVID-19 versus non-COVID-19 admissions. Results: Out of 6480 non-elective admissions, 620 (9.6%) had a diagnosis of COVID-19. They were older (73.3 vs 67.7yrs), more often male (54.7% vs 50.1%), had higher index NEWS (4 vs 2.5) and NEWS2 (4.6 vs 2.8) scores and higher in-hospital mortality (32.1% vs 5.8%). The c-statistics for predicting in-hospital mortality in COVID-19 admissions was significantly lower using NEWS (0.64 vs 0.74) or NEWS2 (0.64 vs 0.74), however these differences reduced at 72hours (NEWS: 0.75 vs 0.81; NEWS2: 0.71 vs 0.81), 48 hours (NEWS: 0.78 vs 0.81; NEWS2: 0.76 vs 0.82) and 24hours (NEWS: 0.84 vs 0.84; NEWS2: 0.86 vs 0.84). Increasing NEWS2 values reflected increased mortality, but for any given value the absolute risk was on average 24% higher (e.g.NEWS2=5: 36% vs 9%). Interpretation: NEWS2 is a valid predictor of the mortality risk but substantially underestimates the absolute mortality risk in COVID-19 patients. Clinical staff