OBJECTIVES: Low-dose azithromycin is one of the recommended treatments for prevention of acute exacerbations of Chronic Obstructive Pulmonary Disease (COPD). However, the cost-effectiveness of this treatment has not been well studied, especially with consideration of costs associated with adverse events.

METHODS: Using a previously validated health economics model of COPD for Canada, we evaluated the cost-effectiveness of adding daily azithromycin to inhaled therapies, compared with continuation of inhaled therapies (standard of care) over 20 years in patients according to 12-month exacerbation history (guideline-recommended frequent exacerbators [≥2 moderate or ≥1 severe events], any positive history [≥ 1 moderate/severe events] and negative history [0 moderate/severe events]). Parameters were collected from the literature. The benefit of azithromycin was modelled as a reduction in exacerbation rates. Adverse events included cardiovascular death, hearing loss, gastrointestinal symptoms, and antimicrobial resistance (leading to decline in azithromycin effectiveness). The incremental cost effectiveness ratio (ICER) was defined as incremental cost per quality adjusted life year (QALY), with all outcomes discounted at 1.5%/year.

RESULTS: In frequent exacerbators, azithromycin use was associated with $43,304 costs, 6.56 QALYs, and 3.29 exacerbations per patient over 20 years. The corresponding values were $42,597, 6.48, and 3.55 for the comparator group. Compared with usual care, azithromycin resulted in ICER $8,837 per QALY gained for patients with positive exacerbation history, and $20,460 for patients with any positive exacerbation history. However, azithromycin was dominated in patients with negative exacerbation history.

CONCLUSIONS: Long-term therapy with azithromycin is cost-effective among COPD patients with ≥1 exacerbations in the previous year. These findings indicate that current guidelines can extend their recommendation for the use of azithromycin from frequent exacerbators to patients who exacerbate (even once) while on maximum inhaled therapies.