A retrospective cohort study design involving secondary data collection was chosen to appropriately address the primary objective in a relatively short period of time after enrollment phase initiation: in fact, since the Italian Sampling Program on benralizumab was active since July 2018, clinical data on patients exposed to benralizumab are already available. No treatments will be administered per protocol requirement, but instead according to normal clinical practice; since benralizumab first administration occurs before inclusion in the study (as per chosen study design), the decision to include the patient in the study is clearly separated from the prescription of benralizumab, in accordance with the observational nature of the study. In order to be eligible for the study, for each patient, the index date shall be at least 3 months prior to enrollment.
