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

Author’s response:

Your statement that the evidence-based answer regarding the lack of benefit of azithromycin in patients ≤65 years of age, with stage IV COPD, current smokers, and patients not using oxygen is “misleading” is a bit of an overstatement.

It is fair to say, however, that our statement regarding lack of efficacy among these subgroups of patients should be softened a bit since the data are from subgroup analyses, which should never be the source of definitive conclusions. And you point out that the 95% confidence intervals [CIs] of the HRs for these subgroups of patients do not include a potentially significant effect (0.68, 0.71, 0.61, and 0.65, respectively), so it is possible there is a Type II error, which would lead one to conclude there is no effect for these subgroups when there is one.

Regarding oxygen therapy, in this Clinical Inquiry, we presented data from the direct subgroup analysis, which revealed no difference in COPD exacerbations between the azithromycin and placebo groups for patients not receiving long-term supplemental oxygen (HR=0.80; 95% CI, 0.62-1.03); however, you are correct to point out that the oxygen use subgroup interaction (patients on oxygen vs patients not on oxygen), which we did not include in this Clinical Inquiry, did not reach significance (P=.23), casting some doubt on the authors’ conclusion of no effect for patients not on oxygen.

On the whole, I feel this Clinical Inquiry accurately summarized the existing evidence and that additional research is needed to better define the utility of azithromycin in these subgroups of patients.

Corey Lyon, DO
Denver, Colo