Craft material and results of platelet inhibitor trials in peripheral arterial reconstructions: reappraisal of results from a mete-analysis

Aims To investigate the characteristics of published trials in order to est ablish the origin of the differing results obtained in trials of platelet i nhibitors after peripheral bypass procedures. Methods Analysis of the information from 11 randomised, controlled trials o f platelet inhibitors after peripheral bypass procedures published up until 1999 and involving 2302 patients undergoing peripheral bypass operations, 1250 of whom were treated with platelet inhibitors. Results There is a significant treatment benefit of platelet inhibitors on meta-analysis of the trials, but a significant heterogeneity amongst the in dividual trial results. The proportion of patients in a trial with prosthet ic grafts was a significant factor in explaining the heterogeneity. Proport ion of prosthetic grafts was associated with sample size and with the propo rtion of grafts above the knee, but these were not found to make an indepen dent contribution to the heterogeneity observed. The platelet inhibitor reg imen used, the severity of ischaemic symptoms and the proportion of smokers included were also not found to be important. Conclusions The improvement of graft patency by aspirin and related platele t inhibitors in clinical trials in peripheral bypass procedures can be attr ibuted to an effect on patients with prosthetic grafts. There is little evi dence that these agents prevent occlusion of vein grafts. The conclusion of an earlier meta-analysis that antiplatelet agents should be used for all b ypasses is not supported.