Utility of established prognostic scores in COVID-19 hospital admissions: multicentre prospective evaluation of CURB-65, NEWS2 and qSOFA

Abstract

Introduction: The COVID-19 pandemic is ongoing, yet, due to the lack of a COVID-19-specific tool, clinicians must use pre-existing illness severity scores for initial prognostication. However, the validity of such scores in COVID-19 is unknown.

Methods: The North West Collaborative Organisation for Respiratory Research performed a multicentre prospective evaluation of adult patients admitted to the hospital with confirmed COVID-19 during a 2-week period in April 2020. Clinical variables measured as part of usual care at presentation to the hospital were recorded, including the Confusion, Urea, Respiratory Rate, Blood Pressure and Age Above or Below 65 Years (CURB-65), National Early Warning Score 2 (NEWS2) and Quick Sequential (Sepsis-Related) Organ Failure Assessment (qSOFA) scores. The primary outcome of interest was 30-day mortality.

Results: Data were collected for 830 people with COVID-19 admitted across seven hospitals. By 30 days, a total of 300 (36.1%) had died and 142 (17.1%) had been in the intensive care unit. All scores underestimated mortality compared with pre-COVID-19 cohorts, and overall prognostic performance was generally poor. Among the 'low-risk' categories (CURB-65 score<2, NEWS2<5 and qSOFA score<2), 30-day mortality was 16.7%, 32.9% and 21.4%, respectively. NEWS2≥5 had a negative predictive value of 98% for early mortality. Multivariable logistic regression identified features of respiratory compromise rather than circulatory collapse as most relevant prognostic variables.

Conclusion: In the setting of COVID-19, existing prognostic scores underestimated risk. The design of new prognostic tools should focus on features of respiratory compromise rather than circulatory collapse. We provide a baseline set of variables which are relevant to COVID-19 outcomes and may be used as a basis for developing a bespoke COVID-19 prognostication tool.

Keywords: pneumonia; respiratory infection; viral infection.

Figure 1

Patient flowchart describing cohort for each analysis and missing data. Analysis of CURB-65 scores was restricted to patients with consolidation on chest radiograph. CURB-65, Confusion, Urea, Respiratory Rate, Blood Pressure and Age Above or Below 65 Years; FiO₂, fraction of inspired oxygen.

Figure 2

Receiver operating characteristic plots for death within 72 hours and ICU admission based on the models defined as the sum of the corresponding predictors. Circles denote the sensitivity and specificity achieved by the optimal threshold from fitted models. AUC, area under the curve; CUCAF-SR, Clinical Frailty Scale, Urea, Consolidation, Age, FiO₂, Sex, Respiratory rate; CUCA-SF, Clinical Frailty Scale, Urea, Consolidation, Age, SpO₂, FiO₂; CURB-65, Confusion, Urea, Respiratory Rate, Blood Pressure and Age Above or Below 65 Years; ICU, intensive care unit; NEWS2, National Early Warning Score 2; qSOFA, Quick Sequential (Sepsis-Related) Organ Failure Assessment.

Figure 3

Calibration plots of the predicted risk of 30 day mortality (based on published validation studies) for CURB65, NEWS2 and qSOFA against observed risk in COVID-19 hospital admissions. CURB-65, Confusion, Urea, Respiratory Rate, Blood Pressure and Age Above or Below 65 Years; NEWS2, National Early Warning Score 2; qSOFA, Quick Sequential (Sepsis-Related) Organ Failure Assessment.