Validation of the British Society of Thoracic Imaging guidelines for COVID-19 chest radiograph reporting

AIM: To validate the British Society of Thoracic Imaging issued guidelines for the categorisation of chest radiographs for coronavirus disease 2019 (COVID-19) reporting regarding reproducibility amongst radiologists and diagnostic performance. MATERIALS AND METHODS: Chest radiographs from 50 patients with COVID-19, and 50 control patients with symptoms consistent with COVID-19 from prior to the emergence of the novel coronavirus were assessed by seven consultant radiologists with regards to the British Society of Thoracic Imaging guidelines. RESULTS: The findings show excellent specificity (100%) and moderate sensitivity (44%) for guideline-defined Classic/Probable COVID-19, and substantial interobserver agreement (Fleiss' k=0.61). Fair agreement was observed for the “Indeterminate for COVID-19” (k=0.23), and “Non-COVID-19” (k=0.37) categories; furthermore, the sensitivity (0.26 and 0.14 respectively) and specificity (0.76, 0.80) of these categories for COVID-19 were not significantly different (McNemar's test p=0.18 and p=0.67). CONCLUSION: An amalgamation of the categories of “Indeterminate for COVID-19” and “Non-COVID-19” into a single “not classic of COVID-19” classification would improve interobserver agreement, encompass patients with a similar probability of COVID-19, and remove the possibility of labelling patients with COVID-19 as “Non-COVID-19”, which is the presenting radiographic appearance in a significant minority (14%) of patients.