Validity of hospital diagnostic codes to identify SARS-CoV-2 infections in reference to polymerase chain reaction results: a descriptive study

Cristiano S Moura; Autumn Neville; Fangming Liao; Bijun Wen; Fahad Razak; Surain Roberts; Amol A Verma; Sasha Bernatsky

doi:10.9778/cmajo.20230033

Validity of hospital diagnostic codes to identify SARS-CoV-2 infections in reference to polymerase chain reaction results: a descriptive study

CMAJ Open. 2023 Oct 24;11(5):E982-E987. doi: 10.9778/cmajo.20230033. Print 2023 Sep-Oct.

Authors

Cristiano S Moura¹, Autumn Neville¹, Fangming Liao¹, Bijun Wen¹, Fahad Razak¹, Surain Roberts¹, Amol A Verma¹, Sasha Bernatsky²

Affiliations

¹ Faculty of Medicine (Moura, Bernatsky), McGill University; Research Institute of the McGill University Health Centre (Neville, Bernatsky), Montréal, Que.; Li Ka Shing Knowledge Institute, St. Michael's Hospital (Liao, Wen, Razak, Roberts, Verma), Unity Health Toronto; Department of Medicine (Razak, Verma) and Institute of Health Policy, Management and Evaluation (Razak, Roberts, Verma), University of Toronto, Toronto, Ont.
² Faculty of Medicine (Moura, Bernatsky), McGill University; Research Institute of the McGill University Health Centre (Neville, Bernatsky), Montréal, Que.; Li Ka Shing Knowledge Institute, St. Michael's Hospital (Liao, Wen, Razak, Roberts, Verma), Unity Health Toronto; Department of Medicine (Razak, Verma) and Institute of Health Policy, Management and Evaluation (Razak, Roberts, Verma), University of Toronto, Toronto, Ont. sasha.bernatsky@mcgill.ca.

Abstract

Background: In 2020, International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) codes were created for laboratory-confirmed SARS-CoV-2 infections. We assessed the operating characteristics of ICD-10 discharge diagnostic code U07.1 within the General Medicine Inpatient Initiative (GEMINI).

Methods: GEMINI assembles hospitalization data (including administrative ICD-10 discharge diagnostic codes, laboratory results and demographic data) from hospitals in Ontario, Canada. We studied adults (age ≥ 18 yr) admitted during 2020 and tested at least once for SARS-CoV-2 via polymerase chain reaction (PCR) during (or within 48 h before) hospitalization. With PCR results as the reference standard, we calculated sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for ICD-10 code U07.1 hospital discharge diagnostic codes. Analyses were stratified by demographic data, calendar period and timing of the first test (within or after 48 h of hospital admission).

Results: In 11 852 hospitalizations with at least 1 SARS-CoV-2 PCR test, 444 (3.7%) were positive. The sensitivity of code U07.1 to identify SARS-CoV-2 infection was 97.8%, specificity was 99.5%, PPV was 88.2% and NPV was 99.9%. Operating characteristics were similar in most stratified analyses, but the specificity and PPV were lower if the first SARS-CoV-2 test was done more than 48 hours after admission.

Interpretation: The sensitivity, specificity, PPV and NPV of code U07.1 were high. This supports using code U07.1 to identify SARS-CoV-2 infection in hospitalization data.