The Dialysis Access Consortium (DAC) was developed to investigate interventions to improve hemodialysis vascular access outcomes in patients with end-stage renal disease (ESRD). The Aggrenox Prevention of Access Stenosis Study (GRAFT) was one of two major clinical trials conducted under the DAC. Surgically created arteriovenous (AV) grafts are the most common type of hemodialysis vascular access in the United States, but fail frequently due to the development of venous stenosis. The GRAFT study was a double-blind, placebo-controlled randomized clinical trial designed to test whether treatment with Aggrenox (dipyridamole and low-dose aspirin) prolonged the primary unassisted patency of newly placed grafts. Participants undergoing placement of a new AV graft for hemodialysis were randomly assigned to receive treatment with Aggrenox or placebo immediately following access surgery. The primary outcome measure was loss of primary unassisted patency, defined as the time from access placement until thrombosis or requirement for intervention to maintain or restore patency. Major secondary outcome measures included cumulative access failure and death. The GRAFT study found that treatment with Aggrenox had a significant but modest effect in reducing the risk of stenosis and improving the duration of primary unassisted patency of newly created grafts.

The GRAFT study sought to determine whether continuous administration of Aggrenox (dipyridamole and low-dose aspirin) prolonged the primary unassisted patency of newly placed grafts.

The primary outcome measure was loss of primary unassisted graft patency (i.e., patency without thrombosis or requirement for intervention), defined as the first occurrence of graft thrombosis, an access procedure performed to correct a stenosis of 50% or more of the diameter of the adjacent normal vessel, or other surgical modification of the graft (e.g., for infection). The major secondary outcome measures included cumulative graft failure, defined as the time from randomization to complete loss of the access site for dialysis, and/or death from any cause.

Patients at least 18 years of age who were scheduled to have a new arteriovenous graft placed for the purpose of hemodialysis and were currently undergoing long-term hemodialysis or were expected to undergo it within 6 months after randomization were enrolled in the study. Exclusion criteria are documented in the study protocol.

The GRAFT study showed that treatment with dipyridamole plus aspirin, as compared with placebo, resulted in a significant but modest decrease in the cumulative incidence of loss of primary unassisted graft patency and clinically significant graft stenosis in patients receiving a new arteriovenous graft for hemodialysis access. The frequency of bleeding or other serious adverse events was not increased with active treatment. The burden of graft failure was substantial, with over three-fourths of patients requiring an intervention to maintain patency or to treat another access site complication within the first year after graft placement.