TY - JOUR T1 - WHAT IS A COPD EXACERBATION? CURRENT DEFINITIONS, PITFALLS, CHALLENGES AND OPPORTUNITIES FOR IMPROVEMENT JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.01261-2018 SP - 1801261 AU - Victor Kim AU - Shawn D. Aaron Y1 - 2018/01/01 UR - http://erj.ersjournals.com/content/early/2018/09/12/13993003.01261-2018.abstract N2 - Chronic Obstructive Pulmonary Disease (COPD) is a chronic illness that may be periodically punctuated by exacerbations, characterised by acute worsening of dyspnea, and/or cough and sputum production, and/or increased sputum purulence. COPD exacerbations are common and carry with them important clinical and economic consequences including lost work productivity, increased utilisation of health care resources, temporary or permanent reductions in lung function and exercise capacity, hospitalisation, and sometimes death. Over the past two decades, clinicians and researchers have broadened their goals of treatment of COPD to extend beyond improving lung function and symptoms and have also begun to address the importance of prevention and reduction of exacerbations. However, despite the best efforts of clinicians and guideline committees, current definitions of exacerbations of COPD are imperfect and fraught with problems. The cardinal symptoms of an exacerbation of COPD are nonspecific and can result from acute cardio-respiratory illnesses other than COPD. A proposed definition, which may be more specific than current definitions, suggests that COPD exacerbation be defined as an acute or sub-acute worsening of dyspnoea (≥5 using a 0–10 scale) sometimes but not necessarily accompanied by increased cough and/or sputum volume or sputum purulence. Necessary laboratory criteria for an exacerbation include: oxygen desaturation ≤4% below that of stable state, elevated circulating blood neutrophils or eosinophils (≥9000 neutrophils per mm3 or ≥2% blood eosinophils), and elevated CRP (≥3 mg·L−1), without evidence of pneumonia or pulmonary edema on the chest radiograph, and negative laboratory tests supportive of other etiologies. Herein, we will discuss the current state of the art with respect to how we define COPD exacerbations, associated pitfalls and challenges, and opportunities for improvement.FootnotesThis manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.Conflict of interest: Dr. Kim has nothing to disclose.Conflict of interest: Dr. Aaron has nothing to disclose. ER -