Retrospective secondary data collection observational chart review study. Data collection and analysis will be performed on a cohort of patients who have previously been enrolled on the BPAP. Approximately 300 patients taking part in the BPAP between April 2018 and November 2019 and who meet the eligibility criteria will be recruited to participate in the study.

Data for each participant in the study will be obtained retrospectively with a focus on obtaining data at baseline (12 months prior to first benralizumab dose or at first assessment in the severe asthma center if <12 months), Index date (date of first benralizumab dose) and at least up to 24 months after index date.

Primary Objectives

• To describe baseline demographic and clinical characteristics of severe eosinophilic asthma patients enrolled in the BPAP
• To describe background treatment patterns of severe eosinophilic asthma patients at baseline and after benralizumab initiation

Secondary Objectives:

• To describe clinical outcomes after initiation of benralizumab therapy in severe eosinophilic asthma patients treated with benralizumab at 12 and 24 months
• To describe patients' adherence to benralizumab, persistence and discontinuation rates and reasons for discontinuation at 12 and 24 months

Inclusion Criteria:

• Patients enrolled on the BPAP between April 2018 and November 2019
• Patients who have at least 1 benralizumab injection and with at least 3 months followup data from the time of enrolment into the BPAP
• Patients initiated on benralizumab outside of the BPAP by October 30, 2019.
• Where CRO employees conduct the data extraction, patients must be able and willing to give informed consent to participate in the study

Exclusion Criteria:

• Currently receiving benralizumab or any other biologic drug for the treatment of asthma in a clinical trial
• Refusal or inability to provide informed consent where the CRO will be collecting the data

Severe eosinophilic asthma patients enrolled in the benralizumab patient access programme in UK severe centres. Patients will have had their first benralizumab dose between April 2018 and November 2019 and data will be collected retrospectively between May 2019 and October 2021.