Anticoagulation patients should routinely be assessed for drug interactions and warfarin and aspirin should be one of them. Many patients are on both aspiring and warfarin, but do they need to be?
It turns out that a third of patients on warfarin are on aspirin for no good reason. The problem is that patients on aspirin and warfarin have a higher risk of bleeding. Including, major bleeds and hospitalizations compared to those who are on warfarin alone.
A cohort study of adults enrolled at 6 anticoagulation clinics. They enrolled patients at 6 anticoagulation clinics in Michigan from January 2010-2017. And looked at individuals who were receiving warfarin therapy for Afib or for venous thromboembolism, DVT, and/or pulmonary embolus, without any documentation of a recent heart attack or valve replacement, people who don’t have an additional indication to be on aspirin.
They looked at greater than 6,500 patients with an average age of 66 years. It turns out that about a third of them had no clear therapeutic indication to being on aspirin addition to their warfarin. The outcomes when someone is enrolled in an anticoagulation clinic are usually better than the rest of the wide world out there.
At 1 year, patients receiving combination therapy with warfarin and aspirin compared to those who received warfarin alone had higher rates of overall bleeding, 26% vs 20%; higher rates of major bleeding, the warfarin vs aspirin group 5.7% vs 4.6% in the aspirin alone group; a higher rate of emergency department visits, 13% vs 9.8%; a higher rate of hospitalizations for bleeding, 8.1% vs 5.2%.
It’s about a 50% higher rate of hospitalization for bleeding but no improvement in the rate of thrombosis. The take-home point here is a real clear one. We need to look when patients are on warfarin. We need to make sure they’re not also on aspirin if there is no clear indication. Aspirin used to be recommended routinely for primary prevention of stroke and of heart attack. Unless someone has a clear and compelling indication for aspirin, when they’re on warfarin get them off the aspirin.
References:
Tillman H, et al. Risk for Major Hemorrhages in Patients Receiving Clopidogrel and Aspirin Compared With Aspirin Alone After Transient Ischemic Attack or Minor Ischemic Stroke: A Secondary Analysis of the POINT Randomized Clinical Trial. JAMA Neurol. 2019 Apr 29 [Epub ahead of print]. doi:10.1001/jamaneurol.2019.0932
