Catching "Early" COPD - The Diagnostic Conundrum.

Chronic obstructive pulmonary disease (COPD) remains a leading cause of morbidity and mortality worldwide. Despite this, there has been little progress so far in terms of disease-modifying therapies over the last few decades and this is in part due to poor understanding of the definition and mechanisms surrounding early disease before it becomes established and increasingly complex. In this review, the nuances and difficulty in defining early disease in COPD are discussed. There are clear benefits in identifying patients early; however, usually diagnosis is made in the presence of significant lung damage. We consider what can be learned of early disease from COPD studies and highlight the lack of inclusion of young smokers (who may be at risk of COPD) or those with mild disease. We discuss promising clinical measures that are being used in an effort to detect early disease. These include symptom assessment, lung physiology measures and computed tomography (CT) imaging modalities. There is emerging evidence for the role of neutrophils and their proteinases in early COPD. This may form an important biomarker to investigate the pathophysiological processes of early COPD. Given the importance of the early disease, it is recommended that future COPD studies focus on capturing the earliest manifestations of disease, to understand the initiating mechanisms and to identify novel treatment targets.