Medicare Part D beneficiaries can face as much as 33% coinsurance for some drugs listed in a “specialty tier,” which can result in thousands of dollars in out-of-pocket costs. The concern, of course, is that this level of cost-sharing creates a barrier that may put patients at risk for poor outcomes because they cannot afford the drugs they need.

Jalpa Doshi and colleagues have looked at this issue in three studies of patients with very different conditions: chronic myeloid leukemia, psoriasis, and rheumatoid arthritis. In each case, high cost sharing was associated with reduced or delayed initiation of a drug, low adherence to a prescribed drug regimen, or interruptions in treatments.

We’ve put this evidence together in a handy one-pager [.pdf here] summarizing the results of these studies.