An evidence-based cost-effectiveness model on methods of prevention of posttraumatic venous thromboembolism

Venous thromboembolism (VT) after injury is a major health problem. Literature data on methods of VT prophylaxis are not consistent with regard to safety and efficacy, and a recent evidence-based report could not conclude that any method was superior to any other or to no prophylaxis. Because no study exists on the cost-effectiveness (C-E) of the different methods of prophylaxis, data from the evidence-based report were used to design a C-E analysis. This analysis will assist in the design of future randomized trials with adequate power to show significant outcome differences.

A decision-tree model was designed on the basis of outcomes from the evidence-based report or relevant literature. We then calculated the cost of prevention of VT by one of the most commonly used methods-low-dose heparin (LDH), low-molecular-weight heparin (LMWH), or sequential compression devices (SCDs)-using different probabilities of incidence of VT. Finally, we adjusted the cost for expected years of life after the episode of VT to calculate the cost per life-year saved by preventing VT.

We produced two tables that can be used to calculate the cost per life-year saved for any patient according to his or her age and the method of prophylaxis used. VT prophylaxis becomes less cost-effective as age progresses, because of decreased life-expectancy. With a widely accepted cost limit of $50,000 per life-year saved to indicate cost-effective treatment, LDH is more cost-effective than LMWH or SCDs.

Our C-E model can help future investigators plan VT-related research with appropriate sample sizes to evaluate cost-effective methods of prophylaxis. LMWH and SCDs must demonstrate substantial improvements in measured outcomes to be more cost-effective than LDH. C-E must be incorporated as a primary outcome in future studies comparing different methods of VT prophylaxis.