The purpose of this cross-sectional, multicenter study is to determine the prevalence of an eosinophilic phenotype of blood eosinophil count ≥ 300 cells/mm3 among severe asthma patients who attend to sites specialized in the management of severe asthma in several countries in the AstraZeneca International Region. The prevalence of an atopic phenotype and asthma control, will also be studied.

To determine the prevalence of an eosinophilic phenotype of blood eosinophil count ≥ 300 cells/mm3 among severe asthma patients attending their routine clinical visit at sites specialized in the management of severe asthma in several countries in the AstraZeneca International Region. The prevalence of an atopic phenotype and the status of asthma control, will also be studied. It is expected that this study will contribute to the understanding of severe asthma, ultimately helping to inform therapeutic decisions and addressing patients' needs.

Inclusion Criteria

Patients must fulfil all of the following inclusion criteria to be included in the study:

• Male or female patient, aged 12 years or older by the time of study entry
• Patient visiting a participating center for a routine clinical appointment
• Patient is willing and able to provide a blood sample for IgE and eosinophil levels determination as part of their routine clinical visit
• Diagnosis of severe asthma for at least one year as defined by:
• Treatment with guidelines-suggested medications for Global Initiative for Asthma (3) steps 4-5 asthma
• Patients or their legal guardian, who voluntarily sign and date the informed consent form prior to study entry.

Exclusion Criteria

• Patients with a diagnosis of chronic obstructive pulmonary disease or other chronic respiratory condition beyond severe asthma
• An acute or chronic condition that, in the investigator's opinion, would limit the patient's ability to participate in this study Patients who are currently under a biologic therapy to treat their severe asthma

The study population will include patients from 12 years and older with severe asthma, as per the definition of the GINA 2018 Guidelines (GINA, 2018). Patients will be identified and invited to participate in the study consecutively, as they attend their routine clinical visit at the research centers.

To be included in the study, each patient should meet all the inclusion criteria and none of the exclusion criteria described in the sections below. Patients should provide written, informed consent prior to any study-specific procedures.

The enrolment period will be approximately 8 months or until the required number of patients has been included, whichever occurs first