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.