Comparing the cost effectiveness of psychiatric treatments: bulimia nervosa.

We conducted an exploratory post hoc study that compared the cost effectiveness of five treatments for bulimia nervosa: 15 weeks of cognitive behavioral therapy (CB) followed by three monthly sessions, 16 weeks (Med16) and 24 weeks (Med24) of desipramine (< or = 300 mg/day), and CB combined with desipramine for those durations (Combo16 and Combo24). We illustrate how a treatment's cost effectiveness varies according to when evaluation is done and how effectiveness and cost are defined. At 32 weeks, Med16 appears the most cost-effective treatment, and Combo16 appears the least. At 1 year, Med24 appears the most cost-effective treatment, and Combo16 appears the least. Using this post hoc analysis as an example, we discuss the pitfalls and limitations of cost-effectiveness analysis of psychiatric treatments.