Asthma exacerbations during the pandemic: Time to rethink clinical markers.

Background: Reductions in asthma exacerbations during the coronavirus disease 2019 (COVID-19) pandemic may have an impact on clinical trial enrollment and outcomes. Objective: Our aim was to review clinical studies and reports evaluating asthma exacerbations before and during the COVID-19 pandemic. Methods: We reviewed clinical studies conducted with biologics over the past decade that evaluated asthma exacerbations as the primary end point. We also reviewed recent clinical reports evaluating asthma exacerbations during the COVID-19 pandemic. Results: We showed that studies requiring at least 2 exacerbations in the prior year resulted in a higher number of exacerbations on study in the placebo arm, and conversely, those studies in which exacerbations were not required for entering the study failed to meet the primary end point. This result confirmed that history of prior exacerbations is a good maker to predict future exacerbations. In addition, a review of the literature confirmed a reduction of asthma exacerbations during the COVID-19 pandemic. The data presented are descriptive; no formal statistics were used. Conclusion: Because of the COVID-19 pandemic, historical exacerbations may no longer be the best predictor for exacerbations in a clinical trial or clinical practice. Other clinical markers associated with exacerbations, such as blood eosinophil count and fractional exhaled nitric oxide level, should be considered for enrollment in clinical studies assessing asthma exacerbations.