Revising the link between proton-pump inhibitors and risk of acute myocardial infarction-a case-crossover analysis.

OBJECTIVE

The purpose of this study is to investigate if the prescription of proton-pump inhibitors (PPIs) was associated with a sudden risk of acute myocardial infarction (AMI) while controlling for time-invariant confounding by using a case-crossover design. An association might indicate that physicians take prodromal symptoms of myocardial ischaemia for dyspepsia.

METHODS

We applied a case-crossover design to investigate all AMI patients admitted to the hospital in the Skåne region, Sweden, between Oct 14, 2005 and Dec 31, 2006 and their PPI prescriptions and dispensations 3 months prior to the AMI onset. We retrieved the information about prescribed medication from the Swedish Drug Register containing individual information on all dispensed drugs prescribed in the outpatient care and dispensed in any of the Swedish pharmacies. Additionally, we stratified the analyses by history of AMI.

RESULTS

We identified 3490 AMI cases aged 40 to 90; 61 % were men. The odds ratio for AMI onset in those with a prescription of PPIs during a hazard period of 3 days compared to control periods was 1.36 (95 % confidence interval (CI) 0.82-2.25) in the whole study cohort and 1.66 (95 % CI 1.00-2.76) in those without history of AMI. The corresponding odds ratio (OR) based on the dispensation date (suggesting use of the drug) was 1.26 (95 % CI 0.92-1.72) and 1.29 (95 % CI 0.92-1.83), respectively.

CONCLUSIONS

In our opinion, the previously reported increase in risk of adverse cardiac events in patients using PPIs may reflect the fact that an AMI may be misinterpreted as dyspepsia.