Risk factors for severe disease in patients admitted with COVID-19 to a hospital in London, England: a retrospective cohort study

Abstract

COVID-19 has caused a major global pandemic and necessitated unprecedented public health restrictions in almost every country. Understanding risk factors for severe disease in hospitalised patients is critical as the pandemic progresses. This observational cohort study aimed to characterise the independent associations between the clinical outcomes of hospitalised patients and their demographics, comorbidities, blood tests and bedside observations. All patients admitted to Northwick Park Hospital, London, UK between 12 March and 15 April 2020 with COVID-19 were retrospectively identified. The primary outcome was death. Associations were explored using Cox proportional hazards modelling. The study included 981 patients. The mortality rate was 36.0%. Age (adjusted hazard ratio (aHR) 1.53), respiratory disease (aHR 1.37), immunosuppression (aHR 2.23), respiratory rate (aHR 1.28), hypoxia (aHR 1.36), Glasgow Coma Scale <15 (aHR 1.92), urea (aHR 2.67), alkaline phosphatase (aHR 2.53), C-reactive protein (aHR 1.15), lactate (aHR 2.67), platelet count (aHR 0.77) and infiltrates on chest radiograph (aHR 1.89) were all associated with mortality. These important data will aid clinical risk stratification and provide direction for further research.

Keywords: COVID-19; hospitalisation; severe disease.

Fig. 1.

Kaplan–Meier plot of time to death (reduced y-axis scale). Blue shading corresponds to 95% confidence intervals.

Fig. 2.

Cohort outcomes. CPAP, continuous positive airway pressure; IMV, invasive mechanical ventilation.

Fig. 3.

Kaplan–Meier plot of time to death split into tertiles by predicted risk from the multivariable model.