Diclofenac and acute myocardial infarction in patients with no major risk factors.

AIMS: To explore further a recent finding that long-term users of diclofenac are at increased risk of acute myocardial infarction (AMI) similar to users of rofecoxib and celecoxib.
METHODS: Using the General Practice Research Database, we conducted three separate nested case-control studies of three nonsteroidal anti-inflammatory drugs (NSAIDs) where use started after 1 January 1993--diclofenac, ibuprofen and naproxen. Cases of AMI were identified between 1 January 1993 and 31 December 2000. Relative risk (RR) estimates for AMI in patients with no major clinical risk factors were determined for each NSAID according to number of prescriptions received compared with one prescription. Results were adjusted for variables possibly related to risk of AMI.
RESULTS: There was no material elevation of AMI risk according to the number of prescriptions for ibuprofen [RRs and 95% confidence intervals (CIs) 1.0 (0.6, 1.6) and 1.7 (0.9, 3.1) for use of 10-19 and 20+ prescriptions, respectively, compared with one prescription] or naproxen [RRs 1.0 (0.5, 2.2) and 2.0 (0.9, 4.5) for use of 10-19 and 20+ prescriptions, respectively]. However, a substantial increased risk similar to that obtained in our prior study was found in patients who received >or=10 prescriptions for diclofenac [RRs 1.9 (1.3, 2.7) and 2.0 (1.3, 3.0) for use of 10-19 and 20+ prescriptions, respectively].
CONCLUSIONS: Extensive use of diclofenac substantially increases the risk of AMI. There is little suggestion of such an effect in users of ibuprofen and naproxen.