Chronic obstructive lung disease (COPD) is defined functionally as airflow limitation that is not fully reversible. It is a MAJOR cause of morbidity and mortality in the U.S. and worldwide. COPD has two distinct major, but often coexisting, forms that represent different manifestations of COPD: emphysema and chronic bronchitis. Emphysema can be defined morphologically, either by radiography or pathology, while chronic bronchitis is defined clinically based upon the duration of productive cough and exclusion of other causes. Treatment is focused on preventing progression of disease and the development of acute exacerbations, which are a major cause of hospitalizations, morbidity and mortality. Common to both major forms is small airways inflammation and an abnormal inflammatory response either in large airways (chronic bronchitis) or in alveoli (emphysema).
COPD is also associated with low-grade systemic inflammation and biomarkers that could predict increased risk for mortality from progressive disease or acute exacerbations might be greatly beneficial in providing more intesive surveillance and treatment of this group. A team of researchers led by Tufts University School of Medicine screened blood samples from people in the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) to see if inflammatory biomarkers could predict disease outcome (abstract). The study included 1843 patients who were followed for 3 years. 168 of the 1843 patients (9.1%) died. Serum or plasma levels of fibrinogen, chemokine ligand 18, surfactant protein D, C-reative protein, Clara cell secretory protein-16, interleukin-6, IL-8, and tumor necrosis factor-alpha were measured at recruitment and at subsequent visits.
The addtion of a panel of biomarkers significantly improved predictive power and was able to better predict outcomes compared with current clinical variables, including age, BODE index, and hospitalization history. The addition of IL-6 provided the most improvement of discriminatory power, but this was improved further with the addition of all biomarkers measured.