ABSTRACT

Many earlier trials of chronic obstructive pulmonary disease (COPD) therapy assessed lung function as a primary outcome to demonstrate evidence of efficacy of therapy (1,2). However, given the global health, social, and economic importance of COPD exacerbations, the prevention of exacerbations is now recognized as a primary goal of COPD therapy (3). Accordingly, recent clinical trials of maintenance medications for COPD have evaluated their effects on the incidence of COPD exacerbations as a primary study outcome. Because prevention of exacerbations is now being relied upon to demonstrate efficacy of new treatments for COPD, it becomes extremely important for investigators to ensure that correct statistical methods are being used to assess this outcome. If clinical trials are not been consistent in how they count, record, or analyze COPD exacerbation rates, then methodological errors in the assessment of COPD exacerbations can potentially lead to biased or spurious results.