Importance: Symptoms of Post-COVID-19 Condition (PCC) are non-specific and can occur due to other medical conditions, making it a challenge to distinguish PCC from other health conditions.
Objective: To compare the proportion of emergency department (ED) patients who developed symptoms consistent with PCC between those who tested positive for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection and time-matched patients who tested negative.
Design: Observational cohort study that enrolled consecutive eligible patients between October 18, 2020, and February 28, 2022.
Setting: Thirty-three Canadian COVID-19 ED Rapid Response Network sites.
Participants: Eligible patients were aged ≥18 years and tested for SARS-CoV-2. We excluded patients not contacted after 5 attempts, unable to communicate due to language or cognitive barriers, deceased, or those who reported a subsequent positive test or symptomatic infection.
Exposure: SARS-CoV-2 infection.
Main outcome and Measure:Based on the World Health Organization (WHO) clinical case definition, our primary outcome was the proportion of ED patients reporting at least one new PCC-consistent symptom arising in the three months after the ED visit that was still present at the three-month mark and lasted >2 months.
Results: Of 29,838 individuals assessed for eligibility, 6,723 were included (58% SARS-CoV-2 positive; 51% female; mean age, 54.4 years [SD: 17.9]). Among 3,933 test-positive patients, 38.9% (1532/3933, 95% CI: 37.4-40.4%) reported PCC symptoms at 3 months compared to 20.7% (578/2790, 95% CI: 19.2-22.2%) of test-negative patients. Test-positive patients reported experiencing each individual PCC-consistent symptom at least twice as often as test-negative patients. The top three most frequently reported symptoms reported by test-positive patients were post-exertional malaise, dyspnea and memory problems. The most important predictor of subsequent PCC was a positive SARS-CoV-2 test during the index ED visit (adjusted OR=4.42).
Conclusions and Relevance: Over one-third of ED patients with a proven acute SARS-CoV-2 infection met PCC criteria at 3 months post-index ED visit, however one in five test-negative patients also reported PCC-consistent symptoms highlighting the lack of specificity of the WHO clinical case definition. Testing for SARS-CoV-2 during the acute phase of a suspected infection should continue until specific biomarkers of PCC become available for diagnosis and treatment referral.
Trial registration: Clinicaltrials.gov, no. NCT04702945