DSEN Abstract
Validation of COVID-19 Diagnoses in Administrative Health Data

A study conducted by the Canadian Network for Observational Drug Effect Studies (CNODES).

What is the issue?

  • Coronavirus disease 2019 (COVID-19) has had a substantial effect on the Canadian population leading to interest in investigating disease trends, risk factors and treatment effectiveness, and in understanding variations in patient attributes associated with COVID-19 infection and outcomes across patient populations.
  • There is little information about the accuracy of Canadian administrative health data for COVID-19 case ascertainment.

Summary and Key Messages

  • This study provides new information regarding the validity of COVID-19 diagnoses captured in Canadian inpatient hospital records, ED records and outpatient healthcare provider service claims during the first year of the pandemic.
  • This multi-province validation study supports the use of inpatient and ED records as alternatives to population-based laboratory tests for identification of COVID-19 cases during the first year of the pandemic.
  • Our findings do not support the use of outpatient service claims to identify people infected with COVID-19.

Project Lead & Team

For more information, please contact info@cnodes.ca

What was the aim of the study?

  • Our main objective was to assess the validity (i.e., accuracy) of COVID-19 diagnosis coding in hospital discharge abstracts, emergency department (ED) records and outpatient healthcare provider service claims in three Canadian provinces.

How was the study conducted?

  • Population-based inpatient, ED, and outpatient service records were linked to results of SARS-CoV-2 polymerase chain reaction (PCR) tests, which are used to diagnose COVID-19. The study data were from British Columbia, Manitoba, and Ontario for April 1, 2020 to March 31, 2021.
  • Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of COVID-19 diagnosis codes (ICD-10 U07.1) and fee codes were estimated for each quarter in the study period, overall and by province, age group, and sex.

What did the study find?

  • We studied over 19 million Canadian residents and more than 13 million SARS-CoV-2 PCR tests.
  • Validity estimates varied across the three study provinces, but were generally highest for inpatient hospital data.
  • Specificity and NPV were consistently high (i.e., most estimates were > 95%).
  • Hospital discharge abstracts:
    • Overall sensitivity was 86% in the first three months (Apr to Jun 2020), but decreased to 66% in the last three months (Jan to Mar 2021).
    • Overall PPV was relatively stable, from 50% and 66% across quarters.
  • ED records:
    • Overall sensitivity was 60% (first three months) and 48% (last three months).
    • Overall PPV was 77% (first three months) and 68% (last three months).
  • Outpatient service claims:
    • Overall sensitivity was 20% (first three months) and 25% (last three months).
    • Overall PPV was 7% (first three months) and increased to 29% (last three months).
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