Heavy lobbying by the US drug industry has, for the time being, held up studies comparing the clinical efficacy of prescription drugs. The Centers for Medicare and Medicaid Services (CMS), which administers Medicare, has been effectively prevented from using evidence of functional equivalence when deciding whether or not Medicare should approve a particular drug for coverage and Medicaid programmes.

The drug companies argued, prior to legislation being passed, that attempts to determine equivalence between older and most likely cheaper drugs, would discourage manufacturers from developing new and possibly better products, even though they were likely to be more expensive.

Last year Congress considered legislation requiring such comparisons (BMJ 2003;327:642). By the time the President signed into law the new Medicare legislation in December, however, the funding …