Medication costs, adherence, and health outcomes among Medicare beneficiaries.

In a two-year period more than two million elderly Medicare beneficiaries did not adhere to drug treatment regimens because of cost. This poor adherence tended to be more common among beneficiaries with no or partial medication coverage and was associated with poorer health and higher rates of hospitalization. The risk for cost-related poor adherence was especially pronounced among lower-income beneficiaries with high out-of-pocket drug spending. We argue that this pattern of cost-related poor medication adherence should inform the design of Medicare prescription drug benefit legislation.