Dialysis Access Consortium - DAC

May 20, 2009
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Author/Summarized by Author:
Anthony A. Bavry, MD, MPH, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. Boehringer Ingelheim provided extended-release dipyridamole and financial support.
Date Published:
01/01/2009
Date Updated:
05/20/2009
Original Posted Date:
05/20/2009
References

Description:

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

Hypothesis:

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

Exclusions:

  • 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.

Interpretation:

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.

References:

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.

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


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