Higher co-payments reduce use of antidepressants

June 7, 2008

As they struggle to contain skyrocketing medication costs, health plans across the U.S. have responded by implementing multi-tiered formularies requiring higher copayments for 'non-preferred' medications. New research from Brandeis University published in the Journal of Mental Health Policy and Economics suggests that the prevalent multi-tiered formulary system does impact how patients fill anti-depressant prescriptions, even though antidepressants have certain characteristics that can make it difficult for patients to switch medications.

The study evaluated claims and eligibility files for a large nonprofit managed care organization that started introducing its three-tier formulary in 2000. The sample included 109,686 individuals. The study included a comparison group in the same health plan, consisting of members who did not yet have a three-tier formulary. Under the new formulary, certain brand drugs were classified as 'non-preferred' and started costing the patient $25 per prescription instead of $10.

"The patterns of use do change after a three-tier formulary is implemented," said co-author Dominic Hodgkin, a researcher at the Institute for Behavioral Health, the Heller School for Social Policy and Management at Brandeis University. In the study, for the antidepressants that became non-preferred, prescriptions per plan member decreased 11 percent in the three-tier group, and increased 5 percent in the comparison group.

The study found that out-of-pocket spending increased while the health plan's spending per user decreased. Notably, the proportion of plan members using antidepressants decreased, unlike what previous studies have found for other classes of drugs, such as medications for high cholesterol and heart disease, when they faced similar price incentives.

Hodgkin and his colleagues wanted to learn how this dominant approach—by 2003, 78 percent of health plans had adopted multi-tiered formularies—was affecting treatment of depression. Antidepressants are an important class to study for several reasons, the study notes. First, both patients and physicians are believed to be less willing to switch medications.

Second, many patients stop taking antidepressants within three months of beginning treatment. Third, many patients take antidepressants to treat conditions such as insomnia and migraine. The decision to take antidepressants is complex itself, in part because of the nature of depression.

Hodgkin said that continued monitoring of how three-tier formularies affect care is needed.

Source: Brandeis University