Complex antithrombotic therapy and bleeding risk in patients with peripheral arterial disease

Abstract

Abstract Introduction Antiplatelet therapy is the cornerstone of treatment for many atherosclerotic vascular pathologies including peripheral arterial disease (PAD). Patients with PAD often have comorbid conditions that require complex antithrombotic therapy, i.e. combined antiplatelet and anticoagulation. Methods All adult patients undergoing ankle brachial index (ABI) measurements were included in the study. ABI values between 1.00 and 1.40 were considered normal, and values below 1.00 or above 1.40 were considered PAD. Demographic, comorbidity and outcome data were obtained using diagnostic codes from the electronic health record. Three medication classes were analyzed: aspirin, non-aspirin oral antiplatelets (e.g. P2Y12 inhibitors) and oral anticoagulants (warfarin and the direct oral anticoagulants). Medication use was determined for patients who had been on a medication for at least one year. Cox proportional hazard analysis for the time to first bleeding event was analyzed. Bleeding was defined as any bleeding requiring medical evaluation (including clinically-relevant non-major bleeding and major bleeding). Results In all, 40,144 patients were included in the analysis (mean age 66±15, 43% female). Patients with PAD were more likely to be on double therapy (one antiplatelet with anticoagulation) (28% vs 19%) and triple therapy (dual antiplatelet with anticoagulation) (10% vs 4%). Unadjusted hazard ratios for bleeding risk showed increased risk of bleeding for patients with PAD (1.18, 95% confidence interval [CI]: 1.08–1.29), though the association is no longer present after adjustment for antithrombotic therapy. Adjusting for age, sex and PAD class, compared to no antithrombotic therapy, there was increased risk of bleeding for monotherapy (1.91, 95% CI: 1.61–2.26), double therapy (3.40, 95% CI: 2.89–4.00) and triple therapy (5.00, 95% CI: 4.21–5.96). Among medications, aspirin and anticoagulant use was independently associated with the greatest increase in risk of bleeding. Conclusion Patients in PAD are at increased risk of bleeding secondary to antithrombotic therapy. Complex antithrombotic therapy with double or triple therapy confer additional bleeding risk, particularly regimens containing aspirin and oral anticoagulants. Funding Acknowledgement Type of funding source: None