Validity of diagnoses of SARS-CoV-2 infection in Canadian administrative health data: a multiprovince, population-based cohort study

Lisa M Lix; Christel Renoux; Carolina Moriello; Ko Long Choi; Colin R Dormuth; Anat Fisher; Matthew Dahl; Fangyun Wu; Ayesha Asaf; J Michael Paterson; Canadian Network for Observational Drug Effect Studies (CNODES) Investigators

doi:10.9778/cmajo.20220152

Validity of diagnoses of SARS-CoV-2 infection in Canadian administrative health data: a multiprovince, population-based cohort study

CMAJ Open. 2023 Sep 5;11(5):E790-E798. doi: 10.9778/cmajo.20220152. Print 2023 Sep-Oct.

Affiliations

¹ Department of Community Health Sciences (Lix), University of Manitoba, Winnipeg, Man.; Lady Davis Institute (Renoux, Moriello); Departments of Neurology and Neurosurgery, and Epidemiology, Biostatistics and Occupational Health (Renoux), McGill University, Montréal, Que.; George & Fay Yee Centre for Healthcare Innovation (Choi), University of Manitoba, Winnipeg, Man.; Department of Anesthesiology, Pharmacology & Therapeutics (Dormuth, Fisher), University of British Columbia, Vancouver, BC; Manitoba Centre for Health Policy (Dahl), University of Manitoba, Winnipeg, Man.; ICES Central (Wu, Asaf, Paterson), Toronto, Ont. lisa.lix@umanitoba.ca.
² Department of Community Health Sciences (Lix), University of Manitoba, Winnipeg, Man.; Lady Davis Institute (Renoux, Moriello); Departments of Neurology and Neurosurgery, and Epidemiology, Biostatistics and Occupational Health (Renoux), McGill University, Montréal, Que.; George & Fay Yee Centre for Healthcare Innovation (Choi), University of Manitoba, Winnipeg, Man.; Department of Anesthesiology, Pharmacology & Therapeutics (Dormuth, Fisher), University of British Columbia, Vancouver, BC; Manitoba Centre for Health Policy (Dahl), University of Manitoba, Winnipeg, Man.; ICES Central (Wu, Asaf, Paterson), Toronto, Ont.

Abstract

Background: Accurate coding of diagnoses of SARS-CoV-2 infection in administrative data benefits population-based studies about the epidemiology, treatment and outcomes of COVID-19. We describe the validity of diagnoses of SARS-CoV-2 infection recorded in hospital discharge abstracts, emergency department records and outpatient physician service claims from 3 Canadian provinces.

Methods: In this cohort study, population-based inpatient, emergency department and outpatient records were linked to SARS-CoV-2 polymerase chain reaction (PCR; reference standard) test results from British Columbia, Manitoba and Ontario for Apr. 1, 2020, to Mar. 31, 2021. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of diagnoses of SARS-CoV-2 infection were estimated for each quarter in the study period, overall and by province, age group and sex.

Results: Our study encompassed more than 13 million SARS-CoV-2 PCR test results. Specificity and NPV of diagnoses of SARS-CoV-2 infection were consistently high (i.e., most estimates were > 95%). Overall sensitivity estimates were 86.2%, 60.4% and 20.3% in the first quarter for inpatient, emergency department and outpatient cohorts, and 66.2%, 47.5% and 25.0% in the last quarter, respectively. For inpatients, overall PPV estimates ranged from 50.0% to 66.4%. For emergency department patients, overall PPV estimates were 76.9% and 68.3% in the first and last quarters, respectively. For outpatients, PPV estimates were 6.8% and 29.1% in the first and last quarters, respectively.

Interpretation: We found variations in the validity of diagnoses for SARS-CoV-2 infection recorded in different health care settings, geographic areas and over time. Our multiprovince validation study provides evidence about the potential use of inpatient and emergency department records as an alternative to population-based laboratory data for identification of patients with SARS-CoV-2 infection, but does not support the use of outpatient claims for this purpose.