Severe asthma exacerbations in the United States:: Incidence, characteristics, predictors, and effects of biologic treatments.

Abstract Background Patients with severe asthma (SA) have a heightened risk of exacerbations including hospitalization. The real-world, specialist-verified incidence and characteristics of exacerbations among patients with SA in the United States have not been described. Objective To describe the real-world incidence, characteristics, and predictors of exacerbations among patients with SA in the United States. Methods The CHRONICLE study is an ongoing observational study of specialist-treated adults with SA in the United States receiving biologic treatment or maintenance systemic corticosteroids or uncontrolled by high-dosage inhaled corticosteroids with additional controllers. For patients enrolled from February 2018 to February 2020, annualized rates and characteristics of exacerbation-related events were summarized by treatment category for 12 months before enrollment and after enrollment through the latest data collection. Results were further analyzed for subgroups of interest. Results Among 1884 enrolled patients, 53.5% and 12.3% experienced an exacerbation and asthma hospitalization, respectively (0.81 and 0.14 per person-year). Of all exacerbations, 36%, 9%, and 15% required an unscheduled health care provider visit, emergency department visit without hospitalization, and hospitalization, respectively. Among patients not receiving biologics or systemic corticosteroids, higher blood eosinophil count, higher fractional exhaled nitric oxide, and lower total immunoglobulin E level were associated with higher exacerbation rates. Exacerbation rates decreased after starting or switching biologics (n = 1299). Multivariate analyses of enrolled patients revealed previous-year exacerbations or hospitalizations, lack of asthma control, and the geographic region also predicted event risk. Conclusion In this real-world cohort of specialist-treated adults with SA in the United States, there was a substantial burden of exacerbations and associated health care resource utilization. Patients receiving biologics had a lower exacerbation burden. Trial Registration ClinicalTrials.gov Identifier: NCT03373045.