COX-2 inhibitors may be included as part of the broader NSAID category in the model Medicare formulary under development by the U.S. Pharmacopeia.

During a recent meeting of USP's expert committee overseeing the creation of the model formulary, a breakout group reviewed the rheumatology medicines category.

The group concluded that there is no need to break out COX-2s as a "sub-subclass" of medicines. The group believes that it is "adequate to cover" the drugs within the non-steroidal anti-inflammatory drug subclass of the analgesics/antipyretics class.

The USP working group will publish a first draft of its proposed classification system in August (see ¹ Also see "USP Medicare Formulary Design Committee To Host Public Meeting Aug. 27" - Pink Sheet, 2 August, 2004.).

COX-2 manufacturers argue that the products provide a gastrointestinal safety advantage over conventional NSAIDs. The safety benefit is especially important in the elderly, manufacturers maintain.

Insurance companies, however, view the COX-2s as premium-priced products that are required for few patients - particularly given questions about the relative long-term cardiovascular safety profile of the drugs.

Without a separate category, COX-2s would be vulnerable to exclusion from Medicare drug formularies.

Medicare formularies will be required to offer a minimum of two drugs in each class of covered medicines. The USP model classification system will serve as the benchmark for the Centers for Medicare & Medicaid Services to review Medicare formularies to ensure they offer sufficient access.

The discussion on COX-2s illustrates one of the thorniest issues that USP's committee must address: where to draw the separations between drug classes and what criteria to use in making the distinctions.

One approach the committee has been working with is that "the best available evidence will be used to justify subclasses based on clinical outcomes."

Within rheumatology, the breakout group advised against subclassification of corticosteroids and NSAIDS, but also recommended that antineoplastic agents should be further subdivided.

In the antihypertensive category, the USP committee appears to be leaning against subdividing the calcium channel blocker class. Diuretics, on the other hand, appear slated for subclassification.

The committee is also debating whether drug classes that have been superseded by safer or more effective treatments - such as carbonic anhydrase inhibitors for hypertension - should be included in the model.

The design of the model formulary will have profound implications for the program, affecting which companies will participate, which kinds of patients will enroll, and the overall cost for the government.

In developing the classification system, the USP committee appears very sensitive to the potential fallout from its decisions. Discussions have addressed the need to avoid "politicizing" the classifications, especially in regard to categorizing some drugs as "classical" or "standard" while dubbing others "atypical" or "emerging."

The USP committee has also debated the clinical and financial impact that CMS' two-drug per class requirement would have.

When looking at the schizophrenia class prototype, for example, committee members wondered "if it would be enough for a drug plan to have two atypical antipsychotics and two phenothiazines, and whether additional drugs could be handled using the exceptions process."

The USP committee is also debating how to handle off-label uses. The committee is considering drafting two documents for the formulary, one that would classify off-label uses and one that would not.

Under the draft implementing Medicare Part D regulations released July 26, CMS said it expects "that the model categories and classes developed by USP will be defined so that each includes at least one drug that is approved by FDA."

"That is, no category or class would be created for which there is no FDA approved drug and which would therefore have to include a drug based on its 'off-label' indication," the proposed rule states.

Nothing would prevent plans from including coverage of an off-label indication in any given category, CMS noted, "provided FDA has not made a determination that the drug is unsafe for that use."

USP appears to using the International Classification of Diseases-Clinical Modification as the foundation for the formulary.

ICD-CM, which is moving into its 10th revision, is based on a system from the World Health Organization and is maintained by the National Center for Health Statistics and CMS, which also uses it for hospital coding.

Using ICD would give the USP model a disease-based backbone.

An "environmental scan" prepared for the committee by Booz Allen Hamilton surveyed approximately 50 formularies to determine their structure. The results found two basic designs: disease-based and pharmacology-based.

No formulary was entirely within one system or the other, Booz Allen found; each was a mix of the two structures.

"Although disease-based formularies follow the 17-category ICD-9 classification, most of them have considerably more categories because they are mixed structures," USP noted.

USP helped design the Veterans Affairs medication classification system in the 1980s. However, the system has only 30 drug classes, and CMS Administrator Mark McClellan recently said the Medicare formulary will be more extensive (² Also see "Medicare Rx Formulary Will Have More Than VA’s 30 Classes" - Pink Sheet, 19 July, 2004., p. 19).

USP is also continuing to seek other information in constructing the formulary, including a Medicaid database from the State of New York, records from Kaiser-Permanente, and the National Disease & Therapeutic Index from IMS.

From the databases, the committee hopes to glean the "top 500 diagnoses for the Medicare demographic group." The committee is interesting in analyzing the conditions and treatments of the Medicare population.

COX-2s May Be Grouped With NSAIDs In Model Medicare Formulary

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