Cost-effectiveness analysis of escitalopram compared with paroxetine in treatment of generalized anxiety disorder in the United Kingdom

BACKGROUND: Generalized anxiety disorder (GAD) is associated with substantial economic burden. OBJECTIVE: To assess, from a societal perspective, the cost-effectiveness of escitalopram and paroxetine in the treatment of GAD in the UK. METHOD: A decision analytic model with a 9 month time horizon was adapted to the UK setting. Model inputs included drug- and nondrug-specific probabilities from head-to-head trial data, published literature, and expert opinion. Main outcome measures were success (response after 12 wk of treatment and no relapse during the following 24 wk) and costs. Resource use was based on National Institute for Health and Clinical Excellence guidance for GAD patient management, and estimated unit costs came from standard national sources. Human capital approach was used to estimate costs of absence from work. The analysis was performed from the societal perspective. RESULTS: Escitalopram-treated patients were associated with 14.4% higher first-line treatment success and significantly lower discontinuation rates due to adverse events than were those treated with paroxetine. Treatment with escitalopram yielded lower expected costs with greater effectiveness compared with paroxetine. These clinical advantages led to less sick leave and resource use as a result of lower switch rates and use of secondary care. Total expected 9 month costs were 21408 ($2560 US) lower for escitalopram-treated patients than for paroxetine-treated patients. Sensitivity analyses on key parameters demonstrated robustness of the model. CONCLUSIONS: Escitalopram appears to be cost-effective compared with paroxetine in the treatment of GAD in the UK