Purpose: Generalized anxiety disorder (GAD) is the most common anxiety disorder with a lifetime prevalence of 6.2% and is associated with substantial economic burden. The objective of this study was to conduct a head-to-head comparison of duloxetine and venlafaxine XR for the long term treatment of GAD.
Method: Cost-effectiveness (CE) analysis was conducted from a U.S. third party perspective. A decision analysis model was developed using data from published randomized clinical trials and meta-analysis. Direct costs were considered which included drug acquisition cost, cost of medical care (general physician and psychiatric visits), hospitalization, and laboratory services for a period of one year. Additionally, the costs associated with the treatment-emergent adverse events as well as discontinuation-emergent adverse events were considered. All costs were adjusted to 2010 dollars using consumer price index. The primary outcome measure in the study was mean change from baseline to endpoint in the Hamilton Anxiety Scale (HAMA) total score. One way sensitivity analysis was performed on average (yearly) drug acquisition costs, using a standard deviation of 15% for each drug and the incremental cost-effectiveness ratio (ICER) was computed.
Result: Mean change in the Hamilton Anxiety Scale (HAMA) total score and total cost for duloxetine and venlafaxine XR was 11.8, 12.4 and $4089.04, $2778.55, respectively. The expected cost per unit change in HAMA score of Venlafaxine XR was $224.08 while that of duloxetine was $346.53. One-way sensitivity analysis duplicated earlier results which underscored the robustness of the model. An ICER demonstrated duloxetine ($4089.04) to be more costly and less effective than venlafaxine XR ($2778.55).
Conclusion: Venlafaxine in our study was a more cost effective option for the treatment of GAD as compared to duloxetine.
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