Cost effectiveness of antidepressant treatment reassessed

Background - A recent simulation concluded that the serotonin-specific reuptake inhibitor (SSRI) paroxetine was more cost-effective than the tricyclic antidepressant (TCA) imipramine, despite substantially higher medication acquisition costs. Method - We replicated the previous model and revised key assumptions which drove the results. The revised model was subjected to sensitivity analysis. Results - Most scenarios in the revised model showed that the TCA is equally or more cost-effective than the SSRI. Model revisions producing these results were changes in assumptions about switched treatment success rates, treatment length and initial treatment success. The revised model appears sensitive to drug acquisition and delivery costs and costs of treatment failure. Conclusions - Based on the model, a policy of using TCAs as first-choice antidepressant treatment, with SSRls reserved for those patients not doing well initially, appears more cost-effective than the reverse sequence. Given limitations in current knowledge about key parameters to include in a;simulation model, large prospective random-assignment cost-effectiveness studies are needed.