Study Findings Question COX-2 Drug Cost Effectiveness

ST. LOUIS, December 12, 2003 – Findings reported in a study published today by The American Journal of Managed Care call into question the cost effectiveness of the new, more expensive COX-2 anti-inflammatory drugs. Using data representing actual clinical practice, researchers sought to validate the rate of co-prescribing of agents used to protect the gastrointestinal tract — a key assumption made in prior COX-2 cost-effectiveness studies.

COX-2 drugs offer greater protection from adverse gastrointestinal events than lower-cost, traditional nonsteroidal anti-inflammatory drugs, although both types are equally effective in treating pain.

As a result, estimates of COX-2 cost effectiveness assumed – based on expert opinion – that most physicians prescribing COX-2 drugs would either stop or dramatically reduce their prescribing of a second drug to protect the gastrointestinal system, which occurs approximately 25% of the time when traditional NSAIDs are prescribed.

However, researchers at pharmacy benefit manager Express Scripts discovered many COX-2 prescribing physicians actually continued co-prescribing gastroprotective drugs like proton pump inhibitors or H2 receptor antagonists. In fact, the study found that gastroprotective drug use was actually higher for COX-2 patients than for those taking a traditional NSAID – by a margin of 20% vs. 18%.

“These findings call into question the use of expert opinion in estimating practice pattern model inputs prior to a product’s use in clinical practice, warranting a re-evaluation of COX-2 cost effectiveness models,” said lead author Emily Cox, PhD, of Express Scripts. She and her team had examined medical and pharmacy claims data at a Midwestern preferred provider organization.

“The harm from incorrect assumptions, such as those found in the cost-effectiveness evaluations of COX-2s, is that they undermine the efficient allocation of scarce healthcare resources,” added Cox.

This is the second study recently published by Express Scripts researchers on the validity of cost effectiveness evaluations of new drugs. In a September Journal of Managed Care Pharmacy article they reported that economic models used to compare ulcer treatments overstated the cost-effectiveness of more expensive treatments. They looked at treatments that combined antibiotics with either a generic bismuth drug or a more expensive branded proton pump inhibitor (PPI). The more economical bismuth-based treatment was actually the most cost-effective.

In other research on COX-2 drugs, in November The American Journal of Managed Care published another Express Scripts study, which found that most patients given new prescriptions for the drugs had no indication of being at risk for gastrointestinal events.

For more than a decade, Express Scripts has employed a company-paid research staff, which now numbers twelve professionals, four of whom hold PhDs. Many of the studies they conduct are published in peer-reviewed journals, reported in the national media and presented at scientific or professional conferences, including the annual Express Scripts Outcomes Conference held for clients. First published in 1996, the annual Express Scripts Drug Trend Report quickly earned national recognition as the most comprehensive, publicly available analysis of U.S. drug-cost trends. Express Scripts also conducted the first national study of regional variation in prescription-drug utilization patterns across the United States. More information about these and other studies are available at

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