Background: Biologic therapies are indicated in people with poorly controlled asthma despite conventional treatments. Eligibility criteria for biologic therapy vary world-wide and will likely impact the proportion of biologic candidates amongst people with asthma.

Aim: We conducted a systematic review to report the proportion of asthma patients meeting eligibility for biologic therapies world-wide.

Methods: Two reviewers searched MEDLINE, EMBASE and ClinicalTrials.gov for publications from 2000 to 2022. Studies reporting the proportion of adult asthma patients eligible for omalizumab, mepolizumab, benralizumab, reslizumab, dupilumab or tezepelumab were included. Studies of patients receiving biologics or assessing eligibility without phenotyping were excluded. Severe asthma was defined using ATS/ERS criteria.

Results: 15 publications, including patients from 5 continents, were identified. Study populations were highly heterogeneous in demographics, lung function, co-morbidities, symptom burden and disease severity. Of 11,578 patients with asthma, 3,079 had severe asthma. The proportion of patients eligible for biologics ranged from 1-91% in all patients and 24-91% among those with severe asthma. Patients were more likely to be eligible for mepolizumab (2.2-78%), followed by omalizumab (1.6-66%), benralizumab (1.3-53%), reslizumab (0.5-41%) and dupilumab (0.28-2.4%). Higher proportions were reported in severe asthma populations or when OCS use was not a criterion.

Conclusion: The proportion of patients eligible for biologic therapy vary amongst asthma populations world-wide. This is related to clinical differences in the patient populations and biologic eligibility criteria.