Although formularies under Medicare Part D plans vary widely, nearly all plans cover at least one brand-name drug in many commonly prescribed treatment classes, according to data from a study in California.
The researchers studied eight treatment classes, including angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, β-blockers, calcium channel blockers, loop diuretics, selective serotonin reuptake inhibitors, statins, and thiazide diuretics.
They noted how often drugs were included in at least 90% of formularies at copayments of $35 or less without prior authorization.
“Providers can have a difficult time knowing which drug is paid for by Medicare Part D because there are over 1,800 plans and there's a great deal of variation among these formularies,” Dr. Chien-Wen Tseng, of the University of Hawaii and the Pacific Health Research Institute, said in an interview. “[But] despite the large number of plans and variation among their formularies, for most of the treatment classes we examined, we found one or more drugs that were covered by nearly 100% of Part D formularies.”
Nearly all of these widely covered drugs are generics, and the drugs covered by Part D formularies are likely to change as generics become available and as new clinical data are released (JAMA 2007;297:2596–602).
Dr. Tseng said that a Web site that tracks the list of widely covered drugs could help physicians determine which drugs are most likely to be covered and therefore more affordable for patients.
In addition to the inconvenience for doctors, the variations also pose a health problem for patients “because they may not get the drug they need if it's not covered or too expensive.”