Prevention of venous thromboembolism in patients with spinal cord injury: Effects of sequential pneumatic compression and heparin

Objective: To estimate the incidence of and risk factors for venous thromboembolism in patients with acute traumatic spinal cord injury (SCI) and evaluate the effectiveness of sequential pneumatic compression devices (SCD), gradient elastic stockings (GES), and heparin in preventing thromboembolism. Design: Prentice's case-cohort design. Setting: All patients admitted to our hospital between 1976 and 1995 with acute traumatic SCI. Main outcome measures: Demographic characteristics, venous thromboembolism risk factors, methods of surveillance and prophylaxis, and thromboembolic events during the first 6 weeks following injury. Results: Venous thromboembolism occurred in 84 of 428 patients (19.6%). Venous thromboembolism increased from 21% between 1976 and 1979 to 31% between 1980 and 1984, then decreased to 16% between 1985 and 1989 and to 8% between 1990 and 1995. Routine surveillance for venous thromboembolism increased through 1983, and SCD/GES use increased after 1983, with a concurrent decline in incidence of thromboembolism. Multivariate analysis showed that SCD/GES reduced the risk of deep venous thrombosis (DVT) or pulmonary embolism (relative risk, 0.5; 95% CI, 0.28 to 0.90). Multivariate analysis suggested a reduced risk of DVT in patients receiving heparin therapy within the first 14 to 42 days after injury, but estimates of reduced risk were not statistically significant (p = .064 for first 14 days, p = .13 for heparin anytime). Conclusion: The SCD/GES combination and heparin are each effective in preventing venous thromboembolism in individuals' acute traumatic SCI. Effectiveness of heparin prophylaxis may be greatest during the first 14 days after injury, whereas benefit from SCD continues to 6 weeks after injury.