Diagnostic Yield of Screening for SARS-CoV-2 among Patients Admitted for Alternate Diagnoses

Davis, P.; Rosychuk, R. J.; Hau, J. P.; Cheng, I.; McRae, A. D.; Daoust, R.; Lang, E.; Turner, J.; Khangura, J.; Fok, P. T.; Stachura, M.; Brar, B.; Hohl, C. M.

Objectives: To determine the diagnostic yield of screening patients for SARS-CoV-2 who were admitted with a diagnosis unrelated to COVID-19, and identify risk factors for positive tests. Design: Cohort from the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN) registry Setting: 30 acute care hospitals across Canada Participants: Patients hospitalized for non-COVID-19 related diagnoses who were tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between March 1, and December 29, 2020 Main outcome: Positive nucleic acid amplification test (NAAT) for SARS-CoV-2 Outcome measure: Diagnostic yield Results: We enrolled 15,690 consecutive eligible adults who were admitted to hospital without clinically suspected COVID-19. Among these patients, 122 tested positive for COVID-19, resulting in a diagnostic yield of 0.8% (95% CI 0.64% - 0.92%). Factors associated with a positive test included presence of a fever, being a healthcare worker, having a positive household contact or institutional exposure, and living in an area with higher 7-day average incident COVID-19 cases. Conclusions: Universal screening of hospitalized patients for COVID-19 across two pandemic waves had a low diagnostic yield and should be informed by individual-level risk assessment in addition to regional COVID-19 prevalence.