Medicare Part D roulette: potential implications of random assignment and plan restrictions.

Background: Dual-eligible (Medicare/Medicaid) beneficiaries are randomly assigned to a benchmark plan, which provides prescription drug coverage under the Part D benefit without consideration of their prescription drug profile. To date, the potential for beneficiary assignment to a plan with poor formulary coverage has been minimally studied and the resultant financial impact to beneficiaries unknown.

Objective: We sought to determine cost variability and drug use restrictions under each available 2010 California benchmark plan.