Efficacy of Low-Dose versus High-Dose Continuous Cyclic Azithromycin Therapy for Preventing Acute Exacerbations of COPD

<b><i>Background:</i></b> Long-term azithromycin therapy significantly reduces the frequency of COPD exacerbations (ECOPD). However, previous studies have used different dosing regimens, and the efficacy of these regimens has not been compared. <b><i>Objective:</i></b> Compare the efficacy of low-dose with high-dose continuous cyclic azithromycin (CC-A) in severe COPD. <b><i>Methods:</i></b> Patients with severe COPD and repeated exacerbations (ECOPD ≥4 or ≥3 with at least 1 hospital admission in the previous year) were prospectively recruited (January 2017 to December 2019) as a multicenter cohort (from 3 university hospitals in the Barcelona area) and treated with low-dose CC-A: 250 mg 3 times per week (250-CC-A group). This cohort was compared with a historical (January 2007 to December 2013) single-center cohort of severe COPD with frequent ECOPD treated with high-dose CC-A: 500 mg 3 times per week (500-CC-A group). To assess differences in ECOPD prevention according to the administration of low-dose or high-dose CC-A, moderate-to-severe ECOPD was evaluated during the 12-month period before and after starting CC-A therapy. <b><i>Results:</i></b> Fifty-eight patients with severe COPD were evaluated: 37 in the low-dose group and 21 in the high-dose group. The 250-CC-A therapy group achieved a mean reduction in moderate-to-severe ECOPD of 65.6% at 12 months after starting CC-A therapy (with a 61.5% reduction in hospitalizations), while the 500-CC-A group achieved a reduction of 60.5% (with a 44.8% reduction in hospitalizations). No significant differences between 250-CC-A and 500-CC-A dosages were observed in the mean annual reduction of moderate-to-severe ECOPD (<i>p</i> = 0.55) or hospitalizations (<i>p</i> = 0.07) with respect to the year prior to starting CC-A. <b><i>Conclusions:</i></b> Low-dose 250-CC-A therapy over a 1-year period is similar to high-dose 500-CC-A in reducing exacerbation frequency in severe COPD patients with frequent ECOPD despite maximal medical therapy.