The aim of this study is to evaluate usual care versus biomarker-directed care (using blood eosinophil counts) for the management of asthma patients in primary care setting.

The study hypothesizes that BEC is a valuable biomarker that can guide asthma treatment, and result in reduction in asthma exacerbations, better symptom control and improvement in quality of life compared to usual arm in mild to moderate asthma patients in the primary care setting.

Researchers would compare using blood eosinophil count guided to usual care to see if biomarker-directed asthma treatment and management

Inclusion Criteria:

1. Singaporeans or Singapore Permanent Residents
2. Patients aged ≥21 to 65 years old
3. Physician diagnosed asthma for duration of at least 4 weeks
4. On or will be initiated on Global Initiative for Asthma (GINA) 2025 step 1-3) treatment
5. No asthma exacerbations* in the preceding 4 weeks before randomisation
6. Able and willing to attend study appointments approximately every 4-monthly over a 1-year period
7. Able to provide informed consent
8. Stable cardiovascular status (i.e. controlled hypertension, no active symptoms of heart disease or arrhythmias) *Exacerbations are defined as worsening of asthma symptoms requiring systemic corticosteroid for 3 or more days, emergency department visit, or hospitalization

Exclusion Criteria:

1. History of life-threatening asthma requiring intubation or intensive care unit admission
2. Severe asthma or difficult to treat asthma
3. Current use of long-term immunosuppression, LTRA receptor antagonist (Montelukast) and Theophylline or long-term oral steroids
4. Presence of other known causes of eosinophilia besides asthma (e.g. parasitic infection), based on physician's discretion and investigation as per clinical practice and suspicion
5. Current use of beta-blocking agents including eye-drops
6. Use of oral, rectal, or parenteral glucocorticoid within 30 days and/or depot parenteral glucocorticoid within 12 weeks prior to recruitment
7. Known diagnosis of Chronic Obstructive Pulmonary Disease, Interstitial lung disease or bronchiectasis
8. Any significant disease or disorder (eg. Cardiovascular, pulmonary other than asthma, gastrointestinal, hepatic, renal, neurological, musculoskeletal, endocrine, metabolic, malignant, psychiatric, major physical impairment) which, in the opinion of the investigator, may either put the patient at risk because of participation in the study, or may influence the results of the study, or the patient's ability to participate in the study
9. Current enrolment in other interventional clinical trial for asthma
10. Female subjects who are pregnant or planning pregnancy during the study period
11. Planned travel outside of the country for ≥16 consecutive weeks during the study
12. Investigator's assessment of poor capability of following study instructions or comply with study procedures