Abstract
Acute exacerbations in chronic obstructive pulmonary disease (AECOPD) are associated with increased mortality, rate of hospitalization, use of healthcare resources, and have a negative impact on disease progression, quality of life and lung function of patients with chronic obstructive pulmonary disease (COPD). There is an imperative need to homogenize the definition of AECOPD because the incidence of exacerbations has a significant influence or implication on treatment decision making, particularly in pharmacotherapy and could impact the outcome or change the statistical significance of a therapeutic intervention in clinical trials. In this review, using PubMed searches, we have analyzed the weaknesses and strengths of the different used AECOPD definitions (symptom-based, healthcare-based definition or the combinations of both), as well as the findings of the studies that have assessed the relationship of different biomarkers with the diagnosis, etiology and differential diagnosis of AECOPD and the progress towards the development of a more precise definition of COPD exacerbation. Finally, we have proposed a simple definition of AECOPD, which must be validated in future clinical trials to define its accuracy and usefulness in daily practice.