A Retrospective Review of Short-Term Outcomes after Switching Patients from Clopidogrel to Alternative Antiplatelet Therapy

Abstract

Purpose To describe a process used at one facility to switch patients receiving clopidogrel to another antiplatelet therapy when appropriate. Additionally, to evaluate adverse effects in these patients and estimate drug acquisition cost savings. Methods Clinical pharmacists reviewed patient charts and recommended switching antiplatelet therapy where appropriate, based on established facility criteria. Charts were later reviewed in an outcomes assessment for those patients who were switched. Primary outcomes assessed included ischemic and bleeding events; secondary outcomes included net change in use of proton pump inhibitors or histamine H2 antagonists, headache, gastrointestinal (GI) upset, allergy, and clopidogrel reinitiation. Drug acquisition cost savings was also estimated. Results A total of 560 patient charts were reviewed, and 373 clopidogrel prescriptions were discontinued. Outcomes were assessed for 215 patients. In total, 20.9% of patients were taking clopidogrel for indications outside the established criteria. Patients were switched to aspirin (48.8%), Aggrenox plus aspirin (29.3%), Aggrenox only (14%), no antiplatelet (7.4%), or warfarin (0.5%). The total ischemic event rate was 5.6%, with all cerebrovascular ischemic events occurring in patients taking Aggrenox plus aspirin. The mean bleeding rate was 5.6%, with 1 major bleeding event. Headache, GI upset, and allergy were reported only in patients taking Aggrenox (with or without additional aspirin). Primarily because of adverse effects of Aggrenox, 23 patients were restarted on clopidogrel. Estimated drug acquisition cost savings at 12 months was approximately $136,500. Conclusions A large number of patients were taking clopidogrel for indications and/or durations outside established guidelines, and most were satisfactory candidates for other antiplatelet medications. Adverse ischemic and bleeding events were comparable with rates previously reported in literature. Patients who were switched to Aggrenox plus aspirin had the highest rates of ischemic events and adverse drug reactions, and were most likely to restart clopidogrel. Nearly 90% of patients tolerated the new antiplatelet therapy at the time of the outcomes review. As a result, the facility was able to appreciate a drug acquisition cost savings.