Risk Factors For COVID-19 Positivity in Hospitalized Patients in A Low Prevalence Setting

Background: Identifying hospitalized patients with Coronavirus disease 2019 (COVID-19) in a low prevalence setting is challenging. We aimed to identify differences between COVID-19 positive and negative patients. Methods: Hospitalized patients with respiratory illness, or fever, were isolated in the emergency room and tested for COVID-19. Patients with a negative PCR and low probability for COVID-19 were taken out of isolation. Patients with a higher probability for COVID-19 remained in isolation during hospitalization and were retested after 48 hours. Risk factors for COVID-19 were assessed using logistic regression. Results: 254 patients were included, 37 COVID-19-positive (14.6%) and 217 COVID-19-negative (85.4%). Median age was 76 years, 52% were males. In a multivariate regression model, variables significantly associated with COVID-19 positivity were exposure to a confirmed COVID-19 case, length of symptoms before testing, bilateral and peripheral infiltrates in chest X-ray, neutrophil count within the normal range, and elevated LDH. In an analysis including only patients with pneumonia (N=78, 18 positive for COVID-19), only bilateral and peripheral infiltrates, normal neutrophil count and elevated LDH were associated with COVID-19 positivity. Conclusions: The clinical presentation of COVID-19 positive and negative patients is similar, but radiographic and laboratory features may help to identify COVID-19 positive patients and to initiate quick decisions regarding isolation.