Benefits of antithrombotic therapy after infrainguinal bypass grafting: a meta-analysis.

PURPOSE We performed a meta-analysis to ascertain the benefits of antithrombotic therapy for maintaining the patency of vascular grafts following lower extremity bypass operations. METHODS We identified articles using MEDLINE and hand searches of relevant journals for randomized clinical trials that compared the use of antithrombotic therapy with control or placebo therapy. Random-effects (DerSimonian and Laird) analyses were used to determine the risk of graft occlusion following lower extremity bypass operations. We also assessed the odds of secondary outcomes, such as myocardial infarction, cerebrovascular accident, all-cause mortality, and bleeding. RESULTS Sixteen articles met the inclusion criteria of a randomized trial of antithrombotic therapy for the patency of vascular grafts; six were excluded because the analyses involved repeat surgeries or lacked a control group. Of the 10 studies included in the final analysis, seven compared antiplatelet agents with placebo or control, and three compared anticoagulant agents with placebo or control. The 10 studies were homogeneous in spite of differing durations of follow-up. The odds of graft occlusion in the treated group was half that in the placebo or control group. The odds ratio was 0.46 (95% confidence interval [CI]: 0.32 to 0.66) for the 10 studies that reported outcomes at 12 months or longer, 0.50 (95% CI: 0.29 to 0.87) in the five studies with 12-month rates; and 0.58 (95% CI: 0.39 to 0.88) at 24 months. CONCLUSION Antithrombotic therapy decreases the risk of graft occlusion after a vascular operation by about 50% at 12 months and is still protective at 24 months after the operation.