Management of asthma and chronic obstructive pulmonary disease with combination inhaled corticosteroids and long-acting β-agonists: a review of comparative effectiveness research.

The value of combination therapy with inhaled corticosteroids and long-acting β-agonists (ICS/LABA) is well recognized in the management of asthma and chronic obstructive pulmonary disease (COPD). Despite differences in the pharmacological properties between two well-established ICS/LABA products (budesonide/formoterol and fluticasone/salmeterol), data from randomized clinical trials (RCTs) and meta-analyses suggest that these two products perform similarly under RCT conditions. In contrast, a few recently reported real-world comparative effectiveness studies have suggested that there are substantial differences between ICS/LABA combination treatments in terms of clinical and healthcare outcomes in patients with asthma or COPD. The purpose of this article is to provide a brief review of the benefits, as well as the limitations, of comparative effectiveness research (CER) in the therapeutic area of asthma and COPD. We conducted a structured literature review of the current CER studies on ICS/LABA combinations in asthma and COPD. These articles were then used to illustrate the unique challenges of CER studies, providing a summary of study results and limitations. We focus particularly on difficult biases and confounding factors that may be introduced before, during, and after the initiation of therapy. Beyond being a review of these two ICS/LABA combination treatments, this article is intended to help those who wish to assess the quality of CER published projects in asthma and COPD, or guide investigators who wish to design new CER studies for chronic respiratory disease treatments.