Impact of the COVID-19 pandemic on emergency CT head utilization in Ontario-an observational study of tertiary academic hospitals.

PURPOSE: To determine the impact of the Coronavirus disease-2019 (COVID-19) pandemic on the volume, indications, and results of CT heads performed in the emergency department (ED) at Canadian tertiary academic centers in Ontario. METHODS: A retrospective review of consecutive CT head examinations ordered through the ED during the early stages of the COVID-19 pandemic in Canada (March 12-April 8, 2020) was performed and compared with that during the pre-COVID-19 period (February 12-March 10, 2020). CT reports were reviewed for the exam indication and the presence of predefined acute findings. A two-sample t test was utilized to compare the cohorts. Daily averages were calculated for all measures to control for the sample size difference between each period. A p value < 0.05 was considered significant. RESULTS: Of the total 751 CT head reports, 290 (38.6%) were ordered during the pandemic and 461 (61.4%) were ordered pre-pandemic. The average daily volume of CT head orders decreased significantly during COVID-19 compared with that during pre-COVID-19 (10.4 scans/day vs 16.5 scans/day; p = 0.001). In terms of indications, the frequency of "non-traumatic ICH" was significantly lower during COVID-19 compared with that during pre-COVID-19 (p = 0.01). Also, there was a significant increase in acute findings on CT during COVID-19 compared with that during pre-COVID-19 (p = 0.001). CONCLUSION: The decreased volume of emergency CT heads performed during the COVID-19 pandemic was associated with a significant increase in the proportion of cases with acute findings. This could be a result of the pandemic's influence on the health-seeking behavior of patients as well as the decision-making process of ordering clinicians.

Effect of COVID-19 on computed tomography usage and critical test results in the emergency department: an observational study.

BACKGROUND: The effect of the coronavirus disease 2019 (COVID-19) pandemic on new or unexpected radiologic findings in the emergency department (ED) is unclear. The aim of this study was to determine the effect of the COVID-19 pandemic on the number of computed tomography (CT) critical test results in the ED. METHODS: We performed a retrospective observational study of ED CT usage at 4 Ontario hospitals (1 urban academic, 1 northern academic, 1 urban community and 1 rural community) over 1 month during the COVID-19 pandemic (April 2020) and over the same month 1 year earlier (April 2019; before the pandemic). The CT findings from 1 of the 4 hospitals, Hamilton Health Sciences, were reviewed to determine the number of critical test results by body region. Total CT numbers were compared using Poisson regression and CT yields were compared using the χ2 test. RESULTS: The median number of ED CT examinations per day was markedly lower during the COVID-19 pandemic than before the pandemic (82 v. 133, p < 0.01), with variation across hospitals (p = 0.001). On review of 1717 CT reports from Hamilton Health Sciences, fewer critical test results were demonstrated on CT pulmonary angiograms (43 v. 88, p < 0.001) and CT examinations of the head (82 v. 112, p < 0.03) during the pandemic than before the pandemic; however, the yield of these examinations did not change. Although the absolute number of all CT examinations with critical test results decreased, the number of CT examinations without critical results decreased more, resulting in a higher yield of CT for critical test results during the pandemic (46% [322/696] v. 37% [379/1021], p < 0.01). INTERPRETATION: Emergency department CT volumes markedly decreased during the COVID-19 pandemic, predominantly because there were fewer examinations with new or unexpected findings. This suggests that COVID-19 public information campaigns influenced the behaviours of patients presenting to the ED.