Bronchodilator responsiveness or reversibility in asthma and COPD – a need for clarity

Igor Barjaktarevic,1 Robert Kaner,2,3 Russell G Buhr,1,4 Christopher B Cooper1,5 1Division of Pulmonary and Critical Care, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; 2Division of Pulmonary and Critical Care, Weill Cornell Medicine, NY, USA; 3Department of Genetic Medicine, Weill Cornell Medicine, NY, USA; 4Department of Health Policy and Management, Fielding School of Public Health at UCLA, Los Angeles, CA, USA; 5Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USAAsthma and COPD present with multiple overlapping phenotypes,1–3 making a simplified diagnostic separation between the two disease states difficult. From a practical standpoint, the difficulty in differentiating between asthma and COPD has been a limitation and a foundation for criticism of large prospective trials.4 Multiple attempts to better define the population of patients with features of both diseases have been made,5,6 yet a common consensus about the best way to approach this problem is missing. Part of this problem relates to our reliance on oversimplified and relatively crude spirometric definitions of asthma and COPD7 and an incomplete understanding of how to interpret changes after bronchodilator administration. Imprecise definitions of the terms “bronchodilator responsiveness” and “reversibility” add to the confusion in the attempts to distinguish between COPD and asthma. Although the two terms are often used interchangeably in the published literature,8 and their difference may seem to be an issue of semantics, appropriately defining “bronchodilator responsiveness” and “reversibility” is essential for understanding the role of bronchodilator administration in the diagnostic workup of obstructive lung disease