COX-2 inhibitors prescribed to reduce gastrointestinal toxicity prior to the market withdrawals

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been the most popular treatment for arthritis - despite their association with gastrointestinal (GI) complications, including bleeding ulcers and death. When selective cyclooxygenase 2 inhibitors (coxibs) were introduced a decade ago, they were widely hailed as a gastroprotective shield for NSAID users.

Eventually, they were incorporated into the treatment guidelines of both the American College of Rheumatology and the Arthritis Foundation for patients at increased risk of GI complications.. Two gastroprotective strategies for patients prescribed NSAIDs were recommended--either coprescription of a non-selective NSAID with an acid-reducing medication or selection of a COX-2 inhibitor NSAID. Then, clinical studies began to uncover evidence that COX-2 inhibitors and other non-selective NSAIDs may increase the risk of heart attack and stroke. Spurred by these findings and other safety concerns, 2 of the 3 FDA-approved coxibs - rofecoxib, known to consumers as Vioxx, and valdecoxib, known to consumers as Bextra - were withdrawn from the market. Questions regarding the appropriate use of COX-2 inhibitors for arthritis patients - and broader questions regarding prescribing patterns of novel drugs soon after FDA approval - remain.

For answers, a study published in the August 2006 issue of Arthritis Care & Research examines the prescribing patterns of COX-2 inhibitors and other gastroprotective agents for arthritis patients with varying levels of GI risk. Using the Consortium of Rheumatology Researchers of North America (CORRONA) registry, a team of CORRONA investigators evaluated data on 2,690 rheumatoid arthritis (RA) patients treated between March 1, 2004 and September 30, 2004 - the last day rofecoxib was legally sold in the U.S.

Of the patient sample, 1,833 (68.1 percent) were prescribed NSAID agents, 538 (20 percent) were prescribed aspirin , and 319 (11.9 percent) were prescribed an NSAID and aspirin. In contrast to multiple earlier epidemiologic studies that observed that a minority of NSAID users were prescribed gastroprotection, the majority (75.3%) of the 1,833 patients prescribed NSAIDs in the study were prescribed a gastroprotective strategy; the most frequently prescribed gastroprotective strategy was COX-2 inhibitors (65.8%).

The researchers also stratified their analyses by the number of GI risk factors for each patient. For patients with two or more risk factors, 80.2% were prescribed a gastroprotective strategy, primarily using COX-2 inhibitors (68.6%). High rates of NSAID gastroprotection were also observed for patients with one major GI risk factor. However, the authors also observed that 72.0% without traditional GI risk factors were prescribed NSAID gastroprotection, including 64.1% using COX-2 inhibitors. As the authors pointed out, registries cannot identify all of the considerations and risk factors inherent in patient and physician decision-making. .

"The relative GI safety of the COX-2 inhibitor class represented a major therapeutic advance for patients at increased GI risk who require long-term NSAID therapy," states its leading author, Jeffrey Greenberg, M.D., M.P.H. "The challenges associated with limiting diffusion of novel therapeutic agents to broader patient populations are likely to be challenges that cross subspecialty boundaries within the US health care system."

Clinical trials serve to determine the efficacy of a novel drug compound. However, the patient population for which a drug is prescribed frequently expands after FDA approval. This study underscores the potential value of post-marketing observational registries. "As novel therapeutic classes are introduced, early evaluation of prescribing patterns using arthritis registries can determine the appropriateness of prescribing patterns," Dr. Greenberg notes, "and may improve patient outcomes."