Diagnostic yield of screening for SARS-CoV-2 among patients admitted to hospital for alternate diagnoses: an observational cohort study

BMJ Open. 2022 Aug 10;12(8):e057852. doi: 10.1136/bmjopen-2021-057852.


Objectives: To determine the diagnostic yield of screening patients for SARS-CoV-2 who were admitted with a diagnosis unrelated to COVID-19 and to identify risk factors for positive tests.

Design: Cohort from the Canadian COVID-19 Emergency Department Rapid Response Network registry.

Setting: 30 acute care hospitals across Canada.

Participants: Patients hospitalised for non-COVID-19-related diagnoses who were tested for SARS-CoV-2 between 1 March and 29 December 2020.

Main outcome: Positive nucleic acid amplification test 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% to 0.92%). Factors associated with a positive test included presence of 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 hospitalised 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.

Trial registration number: NCT04702945.

Keywords: COVID-19; Diagnostic microbiology; EPIDEMIOLOGY; Organisation of health services.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • COVID-19 Testing
  • COVID-19* / diagnosis
  • COVID-19* / epidemiology
  • Canada / epidemiology
  • Hospitals
  • Humans
  • Pandemics / prevention & control
  • SARS-CoV-2*

Associated data

  • ClinicalTrials.gov/NCT04702945