Background: Laboratory investigations suggest that the simultaneous use of aspirin and ibuprofen may attenuate the antiplatelet effect of aspirin, making it less useful for cardioprotection. To determine if there is clinical evidence of this potentially harmful interaction, we conducted a retrospective matched case-control study.
Methods: All patients issued outpatient prescriptions for aspirin or ibuprofen from January 1, 1990, to December 31, 2000, at the Durham Veterans Affairs Medical Center pharmacy were included in the study. Patients who used aspirin and ibuprofen concurrently were matched against those who used aspirin only by race, sex, age within 10 years, and cholesterol levels (either low-density lipoprotein or total cholesterol) to within 30 mg/dL (0.78 mmol/L). The rate ratio of experiencing a myocardial infarction per patient-month of drug exposure was then determined.
Results: Some 3859 patients received both aspirin and ibuprofen, for a total of 52 139 patient-months of medication use. This group experienced 138 infarctions. The 10 239 patients receiving aspirin only, for a total of 156 417 patient-months of use, experienced 684 infarctions. The rate ratio of having an infarction was 0.61 (95% confidence interval, 0.50-0.73) (P <.001), favoring the group that took aspirin and ibuprofen simultaneously. An analysis of diabetic patients found a rate ratio of 0.48 (95% confidence interval, 0.34-0.66) (P <.001). An examination of patients who spent time in both groups at different times resulted in a rate ratio of infarction during combined use of 0.70 (95% confidence interval, 0.59-0.83) (P <.001).
Conclusion: There does not seem to be an increased risk of myocardial infarction among patients simultaneously consuming aspirin and ibuprofen compared with aspirin alone.