Biomarkers in COPD: time for a deep breath

Chronic obstructive pulmonary disease (COPD) has become recognised as a priority area for management of healthcare resources and development of new therapeutic strategies. This is based largely on economic burden and the excessive morbidity and mortality associated with the condition. The result has been a profusion of publications in recent years, many of which start with the observations that “COPD is currently the fifth and by the year 2020 will become the third or fourth leading cause of morbidity and mortality worldwide”.

More recently, the COPD literature has entered a second phase. This has arisen from the appreciation that COPD is more than a respiratory inflammatory condition and is associated with manifestations outside the lung. This has led to the concept that COPD is a systemic disease and has resulted in a rapid increase in papers exploring this aspect. Initial studies were primarily based on the association of reduced body mass index with severe COPD and common inflammatory pathways have been implicated.¹ In particular, the central role of tumour necrosis factor (TNF)α has been proposed,² and muscle biopsies in patients with COPD have shown apoptotic changes within skeletal muscle³ thought to be the result of the systemic inflammation.

In addition to the association of skeletal muscle dysfunction, it is also being appreciated that other co-morbidities such as cardiovascular disease,⁴ type II diabetes⁵ and osteoporosis⁶ are more commonly associated with patients with COPD than the general population. Indeed, the inflammatory basis for these other conditions is also gradually becoming appreciated, and there are many common pathogenic processes between them and COPD.¹

Research in COPD is now entering its third phase. Many pharmaceutical companies …