Acute exacerbations of chronic obstructive pulmonary disease are accompanied by elevations of plasma fibrinogen and serum IL-6 levels

Background Respiratory tract infections may acutely increase risk from coro nary heart disease (CHD), though the mechanisms have not been defined. Pati ents with chronic obstructive pulmonary disease (COPD) are prone to repeate d exacerbations that are often associated with respiratory infections. Thes e patients also have increased cardiovascular morbidity and mortality. We h ypothesized that transient acute increases in plasma fibrinogen, an indepen dent risk factor for CHD, could occur at COPD exacerbation (mediated throug h a rise in IL6) and thereby provide a mechanism linking respiratory infect ion to risk of coronary heart disease. Methods. 93 COPD patients [mean (SD) age 66.8 (8.1) years] were followed re gularly over one year, with daily diary card monitoring of respiratory symp toms and peak expiratory flow rate (PEFR); 67 patients [mean FEV1 1.06 (0.4 4) 1, FVC 2.43 (0.79) 1] were seen during 120 exacerbations. At each visit spirometry was measured and blood samples taken for plasma fibrinogen and I nterleukin-6 (IL-6) levels. Result. At baseline, the mean (SD) plasma fibrinogen was elevated at 3.9 (0 .67) g/l in the 67 patients with exacerbations during the study and the med ian (IQR) IL-6 at 4.3 (2.4 to 6.8) pg/ml. Plasma fibrinogen increased by 0. 36 (0.74) g/l at exacerbation (p <0.001), with IL-6 levels rising by 1.10 ( -2.73 to 6.95) pg/ml (p = 0.008). There was a relation between the changes in fibrinogen at exacerbation and IL-6 levels (r = 0.348, p <0.001). Multip le regression revealed significantly greater rises in fibrinogen when exace rbations were associated with purulent sputum (b = 0.34 g/l; p = 0.03), inc reased cough (b = 0.31 g/l, p = 0.019) and symptomatic colds (b = 0.228; p = 0.024), Conclusions. Plasma fibrinogen levels were elevated in stable patients with COPD and may contribute to the increased cardiovascular morbidity and mort ality in these patients. COPD exacerbations in-creased serum IL-6 levels, l eading to a rise in plasma fibrinogen. Thus acute rather than chronic infec tion may have a role in predisposing to coronary heart disease or stroke.