The purpose of the study is to investigate, in patients with moderate to severe chronic obstructive lung disease, whether intermittent antibiotic treatment leads to:

• A slower rate of decline in forced expiratory volume in one second (FEV1);
• A reduction in the frequency and severity of exacerbations;
• Fewer hospital admissions for chronic obstructive pulmonary disease (COPD);
• Lower mortality;
• An improved quality of life as compared to a group of placebo treated patients.

Study Population: Patients with moderate to severe chronic obstructive lung disease.

Trial Phase: IV

Study Design: Prospective, randomised, double-blind, placebo- controlled clinical trial.

Study Medicine: Azithromycin.

Drug Administration: Oral.

Drug Dose: 500 mg once daily for 3 days every month.

Duration of Treatment: 3 years

Number of Evaluable Patients: 200 per treatment arm

Number of Included Patients: 400 per treatment arm, 800 patients in total.

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.