Did this COPD Clinical Inquiry miss the mark—or not?

In the Clinical Inquiry, “Does prophylactic azithromycin reduce the number of COPD exacerbations or hospitalizations?” (J Fam Pract. 2018;67:384-385), Lyon et al state that azithromycin “doesn’t benefit patients ≤65 years, patients with GOLD [Global Initiative for Obstructive Lung Disease] stage IV COPD [chronic obstructive pulmonary disease], current smokers, or patients not using oxygen (strength of recommendation [SOR]: B, randomized controlled trials [RCTs]).” These categorical statements are misleading, and clinicians should ignore most of them when considering azithromycin for their patients with severe COPD.

It would be more accurate to say that there may be a diminished efficacy of azithromycin for patients with GOLD IV COPD and age ≤65 years.

The authors cited groups that were identified in a posthoc analysis¹ of the only large trial involving azithromycin for the treatment of COPD to date.²P values for the interaction of azithromycin with GOLD stage (P=.04), smoking (P=.03), and age (P=.02) were significant, but the mean effects (hazard ratios [HRs]) for GOLD stage IV, smoking, and age ≤65 were .84, .99, and .84, respectively. It would be more accurate to say that there may be a diminished efficacy of azithromycin for patients with GOLD IV COPD and age ≤65 years. Only smokers appear to show no response, although the lower end of the 95% confidence interval was 0.71. The P value for the interaction of azithromycin with no long-term oxygen use (P=.23) was not significant, and it is incorrect to infer that oxygen use or nonuse predicts response.

The authors correctly state that the “significance of the results is limited because the study was not originally powered for this level of subgroup analysis,” but this statement is buried later in the article.

David L. Hahn, MD, MS
Madison, Wis

1. Han MK, Tayob N, Murray S, et al. Predictors of chronic obstructive pulmonary disease exacerbation reduction in response to daily azithromycin therapy. Am J Respir Crit Care Med. 2014;189:1503-1508.

2. Albert RK, Connett J, Bailey WC, et al. Azithromycin for prevention of exacerbations of COPD. N Engl J Med. 2011;365:689-698.

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