One-year clinical outcome in patients with acute coronary syndrome treated with concomitant use of clopidogrel and proton pump inhibitors: results from a regional cohort study

OBJECTIVES: We sought to compare the 1-year risk of re-hospitalization for acute coronary syndrome (ACS) between patients taking clopidogrel with proton pump inhibitors (PPIs) vs. clopidogrel without PPIs. MATERIALS AND METHODS: We conducted a retrospective cohort study among 3896 patients with ACS, at low risk for gastrointestinal bleeding, discharged from all hospitals of the Emilia-Romagna region of Italy during the period January-August 2008. Patients' consumption of clopidogrel and PPIs at hospital discharge and follow-up was based on pharmacy refill data. Of these 3896 patients, 90% (n=3519) were prescribed PPIs at hospital discharge and/or at some time during follow-up. RESULTS: At 1-year follow-up, hospitalization for ACS occurred in 15% of patients taking clopidogrel with PPIs vs. 3.4% of those taking clopidogrel without PPIs (P<0.001). No difference in terms of all-cause mortality could be detected between the two groups. At multivariate regression analysis with PPI use as a time-varying covariate, periods of use of clopidogrel with PPIs were associated, at 1-year follow-up, with a significantly higher risk of hospitalization for ACS (hazard ratio 1.29, P=0.025). Notably, this event occurred mostly in patients who underwent revascularization during the index hospitalization (n=3045, hazard ratio 1.52, P=0.004). No significant effect of PPI prescription could be observed in terms of 1-year all-cause mortality and revascularization. CONCLUSION: This study suggests the hypothesis that a concomitant use of clopidogrel and PPIs in patients with ACS, at low risk for gastrointestinal bleeding, having mostly undergone coronary revascularization, is associated with an approximately 30% higher risk of nonfatal hospitalization for ACS