Medicare Part D Covers Many Drugs but Few Brand Names

HONOLULU, June 19 -- Medicare Part D formularies cover nearly all drug classes for treatment of hypertension, hyperlidemia, and depression, with generics accounting for most of the agents.

More than half of the commonly prescribed drugs were covered by at least 90% of reviewed formularies, found Chien-Wen Tseng, M.D., M.P.H., of the University of Hawaii, and colleagues, in a review of 73 California and 43 Hawaii Part D formularies.

Seven of the eight drug classes reviewed had at least one drug that was widely covered, the investigators reported in the June 20 issue of the Journal of the American Medical Association.

The outlier was angiotensin II receptor blockers (ARBs), a class in which there are no generic equivalents. Only one ARB, valsartan (Diovan), was covered and only by 81% of formularies.

Data on coverage came from the Medicare website, which lists Part D plans and lists drugs covered by plan formularies. The authors identified coverage from March 1 through April 15, 2006.

They defined widely covered as a drug that was covered by at least 90% of formularies with a co-pay of or less. Seven of the eight drug classes studied -- -blockers, ACE inhibitors, calcium channel blockers, loop diuretics, statins, selective serotonin reuptake inhibitors (SSRIs), and thiazide diuretics -- had at least one drug that was widely covered.

Typically drug classes that had a wide selection of generic drugs had a number of widely covered drugs. For example four ACE inhibitors, benazepril, captopril, enalapril, and lisinopril, all of which are available as generics, were widely covered.

Likewise, 11 -blockers were widely covered. By comparison just one statin, lovastatin, was widely covered.

In all, 32 of the 34 widely covered drugs were generics, the investigators wrote.

It is unknown whether the widely covered drugs are as effective and safe as drugs that are less well-covered, and this study did not address that question. But the authors noted that "many of the widely covered drugs are well accepted and have been used successfully."

Because generic drugs are more likely to be widely covered, the authors suggested that clinicians concerned about prescribing drugs that will be covered by Medicare plans could "use a shortcut by assuming that generically available drugs are most covered and therefore choosing generic over brand name drugs whenever clinically appropriate."

But they cautioned that although this shortcut could save time, it will not guarantee out-of-pocket savings for Medicare patients because "formulary coverage of generic drugs averaged only 90%; thus, there will still be a potential 10% risk of prescribing a noncovered generic drug."

The study was limited by its design, which included review of formularies in only two states. But the authors pointed out that California is the state with the most Medicare beneficiaries and a higher than average number of Medicare Part D plans. So the findings "represent one out of every 10 Medicare beneficiaries." Hawaii, on the other hand, has fewer plans than the national average of 50 Medicare Part D plans per state, but the findings were similar for Hawaii.