In the Emergency Department, we often have to estimate a patient’s probability of having COVID-19 before test results come back. We may need to make decisions about isolation or cohorting of patients who are suspected positive, or triage low-risk patients to areas of the Emergency Department with shared patient spaces. If we are discharging patients with mild symptoms prior to a definitive test result, a patient’s pre-test probability of having COVID-19 may influence the type of discharge instructions that we give them.
We have developed a simple risk prediction tool that can accurately estimate a patient’s risk of testing positive for COVID-19. To do this, we used data from nearly 30,000 patients who were tested for COVID-19 in Canadian Emergency Departments during the first wave of the pandemic. In addition to specific symptoms and exposure risks, the incidence of COVID-19 in the community was a strong predictor of a patient’s test result. Unlike other scores, we didn’t include data on race or ethnicity as predictors, instead focusing on prevalence in the community (which race and ethnicity are often used as surrogates for).
This risk score can accurately identify patients at sufficiently low risk that they probably don’t need to be tested. It can also identify patients at sufficiently high probability of COVID-19 that initiating empiric therapy such as inhaled or systemic corticosteroids prior to the availability of test results is probably reasonable. This risk score needs to be re-validated for use in vaccinated patients, but should work well for unvaccinated patients.
This post was copyedited by @jamievanderende.
- 1.McRae AD, Hohl CM, Rosychuk R, et al. CCEDRRN COVID-19 Infection Score (CCIS): development and validation in a Canadian cohort of a clinical risk score to predict SARS-CoV-2 infection in patients presenting to the emergency department with suspected COVID-19. BMJ Open. Published online December 2021:e055832. doi:10.1136/bmjopen-2021-055832