Abstract 9385: Longer History of Diabetes Attenuates Benefit of Low-Dose Aspirin for Primary Prevention of Cardiovascular Events: A subanalysis from the JPAD Trial
Benefit of low-dose aspirin for primary prevention of cardiovascular events remains controversial in patients with diabetes. We have conducted the JPAD trial to evaluate whether low-dose aspirin could prevent cardiovascular events in patients with type 2 diabetes and no history of cardiovascular disease. The JPAD trial randomly assigned 2,539 patients to the aspirin group (81 or 100 mg daily) or the no aspirin group, and followed for 4.4 years. In the JPAD main trial, low-dose aspirin did not reduce cardiovascular events overall. On the other hand, the efficacy of aspirin on primary prevention has been proven in general population at high risk by previous clinical trials. Therefore, we hypothesized that longer history of diabetes attenuates aspirin's benefit for primary prevention. The analysis included 2,301 patients whose onset of diabetes was reported. We stratified patients according to quartile duration of diabetes at baseline, and assessed aspirin's benefit for prevention of cardiovascular events. The hazard ratio of aspirin's benefit was 0.90 (95% confidence interval [CI]: 0.50 to 1.61), 1.05 (95% CI: 0.55 to 2.02), 0.90 (95% CI: 0.44 to 1.80), and 0.34 (95% CI: 0.12 to 0.81) for patients with baseline duration of diabetes of ≥12.3, 7.0 to 12.3, 2.9 to 7.0, and <2.9 years, respectively. Next, we analyzed to identify any threshold duration of diabetes below which aspirin's benefit changed. The longer duration of diabetes gradually decreased aspirin's benefit for prevention of cardiovascular events (Figure). Low-dose aspirin significantly reduced cardiovascular events in the patients with baseline duration of diabetes of ≤8 years. These results suggested that longer history of diabetes diminishes benefit of low-dose aspirin for primary prevention of cardiovascular events. Although further studies are needed, our findings might explain that the aspirin's benefit is proven in general population at high risk but not in all patients with diabetes.
- © 2011 by American Heart Association, Inc.