Sixteen studies (including nine RCTs, four prospective cohort studies and three retrospective cohort studies) were included in the review (n= 40,676 patients). The sample size ranged from 16 to 28,320. The majority of included studies were of moderate to good quality. Six RCTs had a Jadad score of at least 3 (ranging from 1 to 5). Five cohort studies had a Newcastle-Ottawa score of at least 6 (ranging from 5 to 7). The median follow-up was eight months (ranging from three months to six years).
Antiplatelet agents and bleeding risk
Of the seven studies which used aspirin as a single antiplatelet agent, three reported an increased risk of bleeding. None of the four studies that used sulfinpyrazone, ticlopidine and clopidogrel as single antiplatelet agents reported an increase in the risk of bleeding.
Of the three studies which used a combination of antiplatelet agents, two studies (aspirin plus clopidogrel, aspirin plus sulfinpyrazone) reported an increased risk of bleeding. One study that used antiplatelet agent in combination with warfarin reported no increase in the risk of bleeding.
Antiplatelet agents and access thrombosis risk
Antiplatelet therapy was associated with a reduced risk of thrombosis in arteriovenous shunts (four studies) and central venous catheters (three studies). The results for arteriovenous grafts were mixed; two of three studies and one of two treatment arms in an additional study reported a reduced risk of thrombosis.