Azithromycin to Modify Bronchiectasis Exacerbation Risk

Inclusion Criteria:

* Adult patients aged 18 years or older.
* Clinically and radiologically confirmed non-cystic fibrosis bronchiectasis (NCFB).
* Diagnosis supported by clinical assessment and high-resolution computed tomography (HRCT).
* Patients attending outpatient clinics, inpatient wards, respiratory follow-up services, or routine bronchiectasis care pathways at Assiut University Hospitals during the enrollment period.
* Suitable for baseline disease-signature assessment.
* Able to undergo protocol-defined clinical, functional, radiological, oxygenation, inflammatory, symptom, and safety assessment.
* Able to complete planned 12-month follow-up.
* Eligible for randomization after baseline safety evaluation.
* Written informed consent obtained from the participant or legal representative.

Exclusion Criteria:

* Cystic fibrosis-related bronchiectasis.
* Traction bronchiectasis due to advanced fibrotic interstitial lung disease as the dominant respiratory diagnosis.
* Active pulmonary tuberculosis at enrollment.
* Active nontuberculous mycobacterial pulmonary disease requiring specific treatment at enrollment.
* Active malignancy or terminal non-respiratory illness expected to prevent planned follow-up.
* Acute life-threatening illness preventing safe enrollment, baseline assessment, or randomization.
* Recent major thoracic surgery or acute thoracic trauma interfering with baseline respiratory assessment.
* Known hypersensitivity, contraindication, or serious intolerance to azithromycin or macrolide therapy.
* Baseline cardiac findings judged by the investigator to make long-term azithromycin unsafe.
* Requirement for long-term maintenance macrolide therapy at enrollment.
* Current long-term maintenance macrolide use that cannot be safely discontinued before enrollment.
* Inability to complete required baseline disease-signature assessment.
* Inability or unwillingness to complete planned 12-month follow-up.
* Refusal to participate.