Dialysis Access Consortium - DAC


The goal of the trial was to evaluate treatment with aspirin plus dipyridamole compared with aspirin plus placebo on hemodialysis graft patency.


Aspirin plus dipyridamole would be more effective in improving hemodialysis graft patency.

Study Design

  • Placebo Controlled
  • Randomized
  • Blinded
  • Parallel
  • Stratified

Patients Screened: 832
Patients Enrolled: 649
Mean Follow Up: 4.5 years
Mean Patient Age: 59 years
Female: 59%

Patient Populations:

  • Patients at least 18 years of age anticipated to undergo arteriovenous graft placement for hemodialysis


  • Pregnant or breast-feeding women
  • Bleeding disorder
  • Active esophagitis, gastritis, or peptic ulcer disease
  • Thrombocytopenia (<75,000/mm3)
  • Liver disease
  • Requirement for anticoagulant or antiplatelet agent other than aspirin
  • Uncontrolled hypertension
  • Allergy to dipyridamole

Primary Endpoints:

  • Primary unassisted graft patency defined as no thrombosis or need for intervention

Secondary Endpoints:

  • Graft failure defined as inability of the graft to mature and be used by 12 weeks
  • Death from any cause
  • Death or cumulative graft failure

Drug/Procedures Used:

After arteriovenous graft placement, patients were randomized to twice daily aspirin (25 mg) and extended-release dipyridamole (200 mg) (n = 321) versus aspirin (25 mg) and placebo (n = 328).

Principal Findings:

Overall, 649 patients were randomized. There was no difference in baseline characteristics between the groups. The mean age was 59 years, 59% were women, body mass index was 31 mg/m2, 66% had diabetes, 25% had two or more prior graft failures, and the duration of hemodialysis before randomization was 23 months.

The incidence of the primary outcome, unassisted graft patency at 1 year, was 28% for aspirin and dipyridamole versus 23% for aspirin and placebo (p = 0.02). Cumulative graft failure was 50% versus 53%, death was 33% versus 35%, and major bleeding was 2% versus 3%, respectively.


Among patients who received an arteriovenous graft for hemodialysis, the addition of dipyridamole to aspirin improved graft patency at 1 year compared with aspirin alone. Despite the small benefit at 1 year, there was no difference in cumulative graft failure, death, or major bleeding.

Maintenance of an arteriovenous graft or fistula remains a difficult problem. A recent study documented that clopidogrel reduces the frequency of fistula thrombosis without affecting fistula patency. A Veterans Affairs Cooperative Trial failed to show that dipyridamole improves arteriovenous graft patency, although there was excess bleeding.


Dixon BS, Beck GJ, Vazquez MA, et al. Effect of dipyridamole plus aspirin on hemodialysis graft patency. N Engl J Med 2009;360:2191-201.

Clinical Topics: Statins

Keywords: Renal Dialysis, Drug Combinations, Body Mass Index, Platelet Aggregation Inhibitors, Veterans, Thrombosis, Ticlopidine, Fistula, Dipyridamole, Diabetes Mellitus

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