This RAND study assessed the impacts of the Medicare Prescription Drug Benefit Program (Part D), finding that, by 2008, 90 percent of seniors had coverage that was at least as generous as the standard Part D benefit.  The study also found that poorer beneficiaries have made the greatest gains in access and out-of-pocket savings under Part D.  The authors conclude most coverage under Part D is comparable to non-Part D plans; however, drug pricing issues and coverage gaps remain. 

Joyce G. F., Goldman D. P., Vogt W. B., Sun E., Jena A. B. (2009). Medicare Part D after two years. American Journal of Managed Care, 15(8): 536-544. http://wwwcgi.rand.org/cgi-bin/health/showab.cgi?key=2009_271&year=2009 

Authors: Geoffrey F. Joyce, Dana P. Goldman, William B. Vogt, Eric Sun, Anupam B. Jena