RESUMO
PURPOSE: To determine the cost effectiveness of duloxetine, a new serotonin norepinephrine reuptake inhibitor, when compared with venlafaxine-XR in treating major depressive disorder. METHODS: A cost effectiveness analysis, using a decision tree modelled outpatient treatment over 6 months. Analytic perspectives were those of society (all direct and indirect costs) and the Ministry of Health of Ontario (MoH) as payer for all direct costs. Rates of success and dropouts were obtained from a meta-analysis of randomized placebo-controlled trials. Costs were taken from standard lists, adjusted to 2005 Canadian dollars; discounting was not applied. One-way sensitivity analyses were performed on monthly acquisition costs and success rates; Monte-Carlo analysis examined all parameters over 10000 iterations. RESULTS: From both perspectives, outcomes all numerically favoured venlafaxine-XR (Expected success = 53% and 57%; symptom-free days [SFDs] = 52.72 and 57.03 for duloxetine and venlafaxine-XR, respectively). Total expected costs/patient treated were, Can dollar 7081 and Can dollar 6551 (MoH), Can dollar 20987 and Can dollar 19 997 (societal perspective), for duloxetine and venlafaxine-XR, respectively. Expected costs/SFD were Can dollar134 and Can dollar 115 (MoH) and Can dollar 398 and Can dollar 351 (societal viewpoint) for duloxetine and venlafaxine-XR, respectively. Although results were sensitive to changes in success rate within the 95% CI, Monte-Carlo analyses using the ICER (incremental cost effectiveness ratio) as outcome found venlafaxine-XR was dominant in approximately 78% of scenarios in both perspectives. CONCLUSIONS: Differences in pharmacoeconomic outcomes found were modest, but in all cases, favoured venlafaxine-XR over duloxetine. Therefore, a possible advantage may exist at the population level in the treatment of major depressive disorder in Canada. Ultimately, a head to head study of the two drugs would be needed to confirm these findings.