These drugs were specifically designed to provide pain relief without the serious gastrointestinal side effects associated with the traditional non-steroidal anti-inflammatory drugs.
Researchers at the University of Nottingham identified patients from 367 UK general practices with a first ever diagnosis of an upper gastrointestinal event (stomach ulcer or bleed). Each case was matched with up to 10 control patients.
Prescriptions for anti-inflammatory drugs and aspirin issued in the three years before the study were identified for both cases and controls.
Of 9407 cases, 45% had been prescribed a conventional non-steroidal anti-inflammatory drug (NSAID) in the previous three years and 10% had been prescribed a COX-2 inhibitor. Of 88,867 controls, 33% had been prescribed an NSAID and 6% had been prescribed a COX-2 inhibitor.
Increased risks of adverse gastrointestinal events were associated with current use of COX-2 inhibitors and with conventional non-steroidal anti-inflammatory drugs. Risks were reduced after adjusting for other factors, but remained significantly increased for naproxen, diclofenac, and rofecoxib, but not for current use of celecoxib.
The use of ulcer healing drugs reduced the risk with all groups of non-steroidal anti-inflammatory drugs, although for diclofenac the increased risk remained significant.
Evidence of enhanced gastrointestinal safety with any of the new cyclo-oxygenase-2 inhibitors compared with non-selective non-steroidal anti-inflammatory drugs is lacking, say the authors.
These results suggest that COX-2 inhibitors may not be as safe as originally thought, although a possible confounding effect cannot be ruled out, they conclude.