Background: We aimed to understand the effects of aspirin dose on outcomes in patients with peripheral artery disease (PAD) as well as their participation in a pragmatic randomized controlled trial.
Methods: In a subanalysis of the Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness (ADAPTABLE) study, we compared aspirin doses (81 vs 325 mg) among participants with PAD and study participation metrics in patients with and without PAD. The primary outcome composite was all-cause mortality, nonfatal myocardial infarction, and nonfatal stroke.
Results: Among 14,662 participants enrolled in ADAPTABLE with PAD status available, 3493 (23.8%) had PAD. Participants with PAD were more likely to experience the primary composite (13.76% vs 5.31%, p < 0.001), all-cause mortality (7.55% vs 3.01%, p < 0.001), myocardial infarction (5.71% vs 2.09%, p < 0.001), stroke (2.45% vs 0.86%, p < 0.001), and major bleeding (1.19% vs 0.44%, p < 0.001). A higher aspirin dose did not reduce the primary outcome in patients with PAD (13.68% vs 13.84% in 81 mg and 325 mg groups; OR 1.05, 95% CI 0.88-1.25). Participants with PAD were less likely to enroll via email (33.0% vs 41.9%, p < 0.0001), less likely to choose internet follow-up (79.2% vs 89.5%, p < 0.0001), and were more likely to change their aspirin doses (39.7% vs 30.7%, p < 0.0001).
Conclusions: ADAPTABLE participants with PAD did not benefit from a higher dose of aspirin and participated in the study differently from those without PAD. These results reinforce the need for additional PAD-specific research and suggest that different trial strategies may be needed for optimal engagement of patients with PAD. (ClinicalTrials.gov Identifier: NCT02697916).
Keywords: antiplatelet therapy; clinical trial methodology; evidence-based medicine; peripheral artery disease (PAD); pragmatic trials.