COX-2 Drugs: New Findings Challenge Cost-Effectiveness

New utilization studies presented at the annual Express Scripts Outcomes Conference challenge the cost-effectiveness of the overall use of COX-2 inhibitors, a newer and widely used class of agents used to treat arthritis, acute pain and other disorders.

COX-2 drugs – Celebrex®, Vioxx®, and Bextra® — while equal in efficacy to traditional non-steroidal anti-inflammatory drugs (NSAIDs), like naproxen and ibuprofen, come at a much higher dollar cost. This added cost, say some studies, is justified by the added reduction in the risk of gastrointestinal side effects. However, key findings from the Express Scripts’ COX-2 studies found that:

* Twenty-nine percent of new COX-2 users had a diagnosis for low back pain, a condition that has not yet been listed as an approved indication for COX-2s.

* Seventy-four percent of new COX-2 users had no evidence of being at risk for gastrointestinal adverse events, calling into question the overall cost-effectiveness of their use in ‘real world’ practice.

* Over half of the new COX-2 users had less than a 60 days supply over one year of follow-up, suggesting that these agents are not being reserved for those requiring long term therapy, where the risk of gastrointestinal adverse events is of greatest concern.

* The rate of concomitant gastro-protective agent use (e.g., proton pump inhibitors such as Prilosec® or H2 antagonists such as ranitidine) among COX-2 users was higher than among non-selective NSAID users, contradicting the assumptions of cost-effectiveness models.

* Approximately half of chronic COX-2 users took aspirin for cardio-protective effects. Half of these users were taking doses of 325mg/day or higher, more than considered necessary for cardio-protection and also negating the gastrointestinal protective effects of COX-2s.

“Although we expected to see COX-2 drugs prescribed for conditions other than FDA approved indications, the extent of ‘off-label’ prescribing was higher than anticipated. Additionally, the extent of short term use, the substantial use in patients not at risk for gastrointestinal adverse events, and the higher than expected rate of co-prescribing with other costly gastro-protective agents, calls into question the cost-effectiveness of the overall use of COX-2s in routine clinical care,” explained Express Scripts’ Manager of Outcomes Research, Emily Cox, Ph.D., lead researcher for the studies.

Based on these studies, Express Scripts will continue to recommend that physicians start patients who are not at risk for gastrointestinal events on a generic NSAID before progressing — if necessary — to a COX-2. The approach is known as step therapy.

“Physicians make the final prescribing decisions based on what they believe is best for their patients. We hope the information provided by our studies of COX-2 utilization proves useful to them,” added Cox.

“COX-2 drugs aside, aspirin therapy has been shown to confer numerous benefits, although use at too high a dose can put an individual at risk for gastrointestinal complications. Individuals may not be aware of the potential for gastrointestinal adverse events from taking too high a dose on a daily basis. When taking aspirin for its cardio- protective effect, patients should ask their doctor if taking only one ‘baby aspirin,’ a day — about 81mg — is sufficient” observed Cox.

The studies of COX-2 usage were based on medical and pharmacy claims data of a Preferred Provider Organization in the Midwest for new COX-2 users, identified as patients with a prescription for a COX-2 from January 1, 2000 to May 31, 2000 and no COX-2 prescription in the 12 months prior. The study of concomitant use of COX-2s and over the counter pain relievers is based on a telephone survey conducted in December 2001 and January 2002 among members receiving COX-2 medication through mail order selected from an Express Scripts client located in the Northeast.

The analyses contained in the 2001 Express Scripts Drug Trend Report are based on prescription medications for a sample of Express Scripts commercial clients that maintain individual member eligibility, while also using Express Scripts for both retail network and mail pharmacy services. Because of the unique demographics and drug coverage for Medicaid recipients and for Medicare beneficiaries receiving drug coverage through Medicare Plus Choice plans, data from these two groups are excluded from the study. The resulting samples of 3 million members in each of the years 2000 and 2001 consist of about two-thirds non-managed care commercial members and one-third managed care commercial members.

Knowledge Networks conducted the consumer opinion survey for Express Scripts. Respondents were consumers aged 21 to 64 years old who have health insurance through their employer or union. The survey was conducted between November 7, 2001 and November 19, 2001, using Knowledge Networks’ nationally representative web-enabled panel. The resulting sample consisted of 1,145 adults. Results had a +/- 3.1 percent margin of error with a 90 percent confidence interval.

Express Scripts is one of the nation’s largest pharmacy benefit management firms.

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