Estimating the cost of a Medicare outpatient prescription drug benefit.

People enrolled in Medicare account for more than one-third of all outpatient prescription drug expenditures in the United States. That being the case, a proposed prescription drug benefit under the Medicare program would insure a substantial part of the market and would create the largest expansion of the program in the past 20 years. This article explains how the cost of a drug benefit was estimated as part of the Clinton Administration's health reform initiative.