Risk of rehospitalization for patients using clopidogrel with a proton pump inhibitor.

Background: Recent pharmacodynamic and retrospective clinical analyses have suggested that proton pump inhibitors (PPIs) may modify the antiplatelet effects of clopidogrel bisulfate.

Methods: We conducted a retrospective cohort study of persons enrolled in a multistate health insurance plan with commercial and Medicare clients to evaluate adverse clinical outcomes in patients using clopidogrel plus a PPI compared with clopidogrel alone. Patients who were discharged from the hospital after myocardial infarction (MI) or coronary stent placement and treated with clopidogrel plus a PPI (n = 1033) were matched 1:1 (using propensity scoring) with patients with similar cardiovascular risk factors treated with clopidogrel alone. Rehospitalizations for MI or coronary stent placement were evaluated for up to 360 days. A subanalysis was conducted to study the impact of pantoprazole sodium, the most used PPI.

Results: Patients who received clopidogrel plus a PPI had a 93% higher risk of rehospitalization for MI (adjusted hazard ratio, 1.93; 95% confidence interval, 1.05-3.54; P = .03) and a 64% higher risk of rehospitalization for MI or coronary stent placement (1.64; 1.16-2.32; P = .005) than did patients receiving clopidogrel alone. Increased risk of rehospitalization for MI or coronary stent placement was also observed for the subgroup of patients receiving clopidogrel plus pantoprazole (adjusted hazard ratio, 1.91; 95% confidence interval, 1.19-3.06; P = .008).

Conclusions: Patients who received clopidogrel plus a PPI had a significantly higher risk of rehospitalization for MI or coronary stent placement than did patients receiving clopidogrel alone. Prospective clinical trials and laboratory analyses of biochemical interactions are warranted to further evaluate the potential impact of PPIs on the efficacy of clopidogrel.