Blood eosinophil count and GOLD stage predict response to maintenance azithromycin treatment in COPD patients with frequent exacerbations.

INTRODUCTION: Maintenance treatment with macrolides are useful in preventing COPD exacerbations. We investigated which characteristics of COPD patients with frequent exacerbations predicted the best response to maintenance treatment with azithromycin. METHODS: This study was part of the COLUMBUS trial, a prospective randomized, double-blind, placebo-controlled study in 92 COPD patients with frequent exacerbations. During the 1-year treatment period, follow-up data were collected for spirometry, mMRC scores, sputum cultures and blood inflammatory markers. RESULTS: In the azithromycin group a significant lower number of exacerbations per patient was observed in patients with the following characteristics: baseline blood eosinophil count ≥2.0% (x̄ = 1.26), compared to an eosinophil count < 2.0% (x̄ = 2.50; p = 0.02), GOLD stage 1-2 (x̄ = 1.06), versus GOLD stage 4 (x̄ = 2.62; p = 0.02) and GOLD group C (x̄ = 0.45) compared to group D (x̄ = 2.18; p < 0.01). Moreover, the number of hospitalizations was significantly lower in patients, with a blood eosinophil count ≥2.0% (x̄ = 0.26) compared to an eosinophil count < 2.0% (x̄ = 0.90; p = 0.01) and in GOLD stages 1-2 (x̄ = 1.06) compared to stage 4 (x̄ = 2.62; p = 0.04). CONCLUSION: In conclusion, azithromycin maintenance treatment appears to be effective in COPD patients with frequent exacerbations, who are either classified in GOLD stage 1-2 or GOLD C and those with a blood eosinophil count of ≥2.0%.