Prevalence and prevention of venous thromboembolism in patients with acute exacerbations of COPD

Background: Little information exists on the prevalence and prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients admitted for acute exacerbations of chronic obstructive pulmonary disease (COPD). Objective: To review available literature, we performed a Medline search on papers published on this topic between 1966 and 2003. Data synthesis: Pulmonary emboli have been frequently found (up to 30% of cases) in autoptic series that included patients who died from acute exacerbation of COPD, while the real incidence of PE during exacerbation has never been prospectively evaluated by large-scale clinical studies. Diagnosis of concomitant PE in these patients is often missed because symptoms of acute exacerbation of COPD may mimic PE, and non-invasive evaluation by pulmonary scintigraphy or CT scan is less specific. Even if not fatal, undetected and untreated PE may lead to long-term morbidity from pulmonary hypertension and predispose to recurrent venous thromboembolism (VTE). DVT of the lower extremities affects about 10% of patients with acute exacerbation of COPD at admission, but the rate is likely to be underestimated. The results of clinical trials conducted on general medical patients, including COPD patients, indicate that unfractionated heparin (UH) and low molecular weight heparin (LMWH) significantly reduce VTE rates. However, subgroup data on COPD patients are generally not available. In a single randomised, controlled trial specifically conducted on COPD patients, nadroparin reduced the rate of DVT from 28% to 15% without affecting mortality. Conclusions: Despite a substantial lack of consistent data, VTE appears as a major threat to patients admitted for acute exacerbation of COPD, and pharmacologic prophylaxis should be considered in all high risk situations. However, methodologically rigorous studies in this setting are still needed.