Prevention of Venous Thromboembolism After Injury

OBJECTIVES: This project's goals are to evaluate the existing literature, summarize the evidence, and perform meta-analysis and cost-effectiveness analysis on data relevant to prevention of venous thromboembolism after injury. Venous thromboembolism occurs frequently after trauma and causes significant mortality and long-term disability. At the same time, methods to prevent and diagnose it are highly controversial and physicians' practices vary widely. With this evidence report, we intend to examine these controversial areas by analyzing the existing scientific literature. An equally important objective is to identify areas in which evidence is lacking in order to direct future research. SEARCH STRATEGY: Three databases were searched: MEDLINE (1966--99), EMBASE (1980--99), and the Cochrane Controlled Trials Register (1980--99). The following medical subject headings were used: Thrombophlebitis, Thrombosis, Thromboembolism, Pulmonary embolism, Wounds and injuries; the subheadings: pc (prevention and control), in (injuries); and the text words: prevent$, thromboprophyla$, prophylac$, trauma$, posttrauma$, post-trauma$. SELECTION CRITERIA: Studies were selected if they specifically reported on methods of venous thromboembolism prevention and screening in trauma patients. Studies including only nontrauma patients were rejected. A panel of technical experts assisted in identifying four key questions: 1.What is the best method of venous thromboembolism prophylaxis? 2.What groups of patients are at high risk of developing venous thromboembolism? 3.What is the best method of screening for venous thromboembolism? 4.What is the role of vena cava filters in preventing pulmonary embolism? Studies were selected if they addressed any of these four questions. DATA COLLECTION AND ANALYSIS: Screening of 4,093 relevant titles by two independent reviewers resulted in acceptance of 2,437 of them for abstract review; 227 of these were accepted for further review. Finally, 73 studies were analyzed. Meta-analysis and supplemental analyses were performed on the available data. MAIN RESULTS: The reported incidence of deep venous thrombosis in trauma patients in the selected studies is 12 percent and varies from 3 percent to 23 percent according to study design, type of trauma population, and method of deep venous thrombosis prophylaxis and diagnosis. The reported incidence of pulmonary embolism in these studies is 1.5 percent and varies from 0.1 percent to 15 percent. Few randomized controlled trials provided data that could be combined for meta-analysis. From the limited data available, there is no evidence that mechanical prophylaxis or low-dose heparin is superior to no prophylaxis or to each other for prevention of deep venous thrombosis. The role of low-molecular-weight heparin in trauma patients is unclear because the few relevant studies are heterogeneous. Spinal fractures and spinal-cord injuries increase the risk of venous thromboembolism. No relevant data are available for drawing conclusions about the best method of screening for venous thromboembolism. Although vena cava filter placement in selected trauma patients may decrease the incidence of pulmonary embolism and fatal pulmonary embolism, the designs of the studies reporting these results do not allow definitive conclusions to be drawn.