The threat in chronic lung diseases: acute exacerbations

Globally, hundreds of millions of people are burdened with chronic respiratory diseases, and pulmonary disorders rank amongst the most frequent causes of death [1]. Acute worsening of chronic lung disease is increasingly recognised as one of the main causes of disease progression, loss of health-related quality of life, and disease-associated mortality. While substantial progress has been made in the long-term management of most chronic lung diseases, our knowledge regarding causes, early identification, essential diagnostic procedures including biomarkers, and especially about disease-modifying treatments of acute worsening, is still in its infancy. Also, the definitions of acute worsening (so-called acute exacerbations) of different chronic lung conditions remain somewhat vague. For example, in chronic obstructive pulmonary disease (COPD), the current update of the Global Strategy for COPD [2] defines an exacerbation of COPD as an acute worsening of respiratory symptoms that results in additional therapy, a definition that nevertheless is good enough for medical decisions or as an end-point in trials. For idiopathic pulmonary fibrosis (IPF), an acute exacerbation is defined as an acute, clinically significant, respiratory deterioration characterised by evidence of new widespread alveolar abnormality [3]. Acute exacerbations are the most acute threat in chronic lung diseases