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National Institutes of Health

Science Update
April 2, 2008

Paying More for Prescriptions May Limit Seniors’ Access to Antidepressants

New cost-sharing policies may prevent some older adults diagnosed with depression from filling new antidepressant prescriptions, according to an analysis published in the April 2008 issue of Psychiatric Services.

The NIMH-funded study examined eight years of data from a British Columbia, Canada, program that evolved from comprehensive prescription coverage to cost-sharing in which seniors were responsible for a part of the costs of their prescriptions.

Adults age 65 and older can suffer from major depression, but treating them with antidepressants can cause problems due to cost and potential interactions with other medications taken. As a result, many of those diagnosed with depression do not fill an antidepressant prescription.

Philip Wang, M.D., Dr. P.H., of NIMH’s Division of Services and Intervention Research, and colleagues analyzed the province’s prescription data from January 1997 to December 2005.  After previously providing comprehensive prescription coverage, in January 2002 the province implemented a $10-25 Canadian co-pay with each prescription. Co-payments require the patient to pay a fixed amount for each prescription.

Then in May 2003, the co-pay policy was replaced with an income-based deductible and a 25 percent coinsurance payment after the deductible was met. Co-insurance requires the patient to pay a portion of the medication price, a potential hardship for people with many prescriptions. After meeting an out-of-pocket ceiling, full coverage kicked in. The transition is similar to what many U.S. retirees experience when they move from private insurance programs to Medicare, which also requires deductibles and coinsurance payments.

The researchers found that while neither policy change resulted in people discontinuing existing antidepressant prescriptions, each coverage policy change was associated with a decrease in the start of antidepressant therapy, suggesting that newly diagnosed seniors may not be filling new prescriptions.

The added costs likely prevented some from starting new prescriptions, said  Wang and colleagues. Also, the researchers speculate that the stigma associated with antidepressants may have curtailed use, especially among those on lower fixed incomes. Wang and colleagues conclude that the consequences of decreases in antidepressant initiation are unclear and will require more research.


Wang PS, Patrick AR, Dormuth CR, Avorn M, Maclure M, Canning CF, Schneeweiss S. The impact of cost sharing on antidepressant use among older adults in British Columbia. Psychiatric Services. 2008 Apr: 59(4): pp 377-383.