Prophylactic Antibiotic Treatment of Patients With Chronic Obstructive Lung Disease (COLD)

Inclusion Criteria: * Patients above 50 years of age, with a current admission for exacerbation of COLD or at least one admission within the previous two years. * Current or ex-smoker * Postbronchodilator FEV1 \< 60% in stable condition (\> 4 weeks after hospitalisation) * \< 300 ml bronchodilator reversibility in FEV1 Exclusion Criteria: * Patients with end-stage COLD, who are not expected to survive for 3 years (typically bedridden patients being dyspnoeic in rest). * Patients with known other respiratory tract infection, e.g. tuberculosis or aspergillosis, in whom the intervention is known to be inefficient. * Patients with pulmonary malignancy * Patients with other pulmonary diseases than COLD. * Patients with immunodeficiency. However, COLD patients treated with steroids can be included. * Patients with known hereditary disposition to lung infections such as alfa-1-antitrypsin deficiency, cystic fibrosis or primary ciliary dyskinesia. * Patients receiving longterm antibiotic treatment ( e.g. recurrent cystitis). * Patients with known allergy or intolerance to azithromycin * Pregnant or breastfeeding women * Manifest heart, liver or renal insufficiency * Patients that, for reasons not stated above, are unlikely to be able to participate in a study period of 3 years.