How Do Seniors Respond to 100% Cost-Sharing for Prescription Drugs? Quality of the Evidence Underlying Opinions About the Medicare Part D Coverage Gap

Popular press coverage of the Medicare Part D coverage gap is based largely on research conducted using retrospective analyses of administrative claims data. These datasets are incomplete because they lack information about methods of obtaining medication that are commonly used by seniors, including free samples, generic drug discount programs, over-the-counter substitution, and patient assistance programs. As a result, evidence about the effects of 100% cost sharing on seniors is limited and suboptimal. Although the current deficit of information about the coverage gap is not entirely unexpected because the Medicare Part D program is relatively new, reliance on claims-based analyses to inform questions that claims data cannot possibly address accurately has tended to mislead and politicize rather than produce constructive policy guidance. Numerous important health policy questions remain unaddressed. These questions are becoming especially important as optimal approaches to providing health care to seniors are the subject of an increasingly vigorous debate.