Pneumonia surveillance and its attendant clinical risk stratification for COVID-19 in low-risk patients

Abstract

Objectives: The objective of the study is to determine the prevalence of COVID-19 in the context of a secondary pneumonia surveillance program targeted at low-risk patients and to identify clinical characteristics associated with COVID-19.

Study design: This study design is a retrospective cohort study.

Methods: This study is conducted in Tan Tock Seng Hospital, a University affiliated 1600-bed public hospital in Singapore. Patients with pneumonia admitted under our Enhanced Pneumonia Surveillance (EPS) program from 7 February 2020 to 20 March 2020 were included. Relevant clinical variables were collated.

Results: Of 1295 patients admitted under our EPS program, 47 (3.6%) patients tested positive for COVID-19. The prevalence of a radiologist-reported normal chest X-ray (CXR) in the COVID-19-positive group was 62.8% compared with 6.2% in the COVID-19-negative group. In patients with a normal CXR, a low normal white blood cell (WBC) count and minimal C-reactive protein (CRP) elevation were associated with COVID-19.

Conclusions: The pick-up rate of COVID-19 in low-risk patients with pneumonia is 3.6%. However, at least 7.9% of patients who were isolated had a normal CXR. For patients with pneumonia-like illness at presentation but a normal CXR, higher WBC and CRP values may guide early deisolation. Ultimately, this informs resource allocation for both COVID-19 and non-COVID-19 clinical services.

Keywords: COVID-19; Chest X-ray; Pneumonia surveillance.