This will be a non-drug interventional cross-sectional study, where the screening visit and study visit can occur on the same day. Investigational product will not be administered. Approximately 790 subjects with severe asthma will be screened to achieve a total of at least 750 evaluable study subjects. The study will not include a run-in or follow-up period. This study will provide a more reliable description of the severe asthma patient landscape with respect to the potential eligibility for treatment with mepolizumab, omalizumab, and reslizumab. This study aims to estimate the potential overlap of patients eligible for treatment with mepolizumab and those eligible for treatment with omalizumab and/or reslizumab. Additionally, the current study will also ascertain and describe reslizumab eligibility with respect to both mepolizumab and omalizumab, in the severe asthma patient population.

Inclusion Criteria:

• At least 12 years of age at study visit.
• Participants eligible for enrolment and entry into the study must meet the following definition of severe asthma, which is based on the definition of severe asthma described in the European Respiratory Society/ American Thoracic Society (ERS/ATS) Guidelines for severe asthma: Asthma which requires treatment with guideline suggested medications for Global Initiative for Asthma (GINA) steps 4-5 asthma for the previous year (i.e., at least 12 months).

Patients must be treated with high dose ICS PLUS at least one of the following: LABA, leukotriene modifier, theophylline, or continuous or near continuous systemic corticosteroid (i.e., maintenance systemic corticosteroid for ≥50% of the previous year).

SPECIAL CIRCUMSTANCE: If patient is on a fixed dose combination medication, then the maximum recommended dose of the ICS/LABA combination per local label is acceptable.

• Able to give written informed consent prior to participation in the study, which will include the ability to comply with the requirements and restrictions listed in the consent form. Participants must be able to read, comprehend, and write at a level sufficient to complete study related materials. A parent or legal guardian must provide informed consent for participants less than 18 years of age at study visit (or less than minimum age to be considered an adult per local laws).

Exclusion Criteria:

Participants who have participated in an interventional clinical trial for asthma within the past 12 months prior to Visit 1 (NOTE: subjects participating in an observational study where an investigational product or procedure is not administered will not be subject to this exclusion criteria)