Pharmacoeconomic Evaluation of Antimuscarinic Agents for the Treatment of Overactive Bladder

STUDY OBJECTIVE: To compare the cost-effectiveness of various antimuscarinic agents for the treatment of overactive bladder (OAB). METHODS: A decision-analysis model was developed and included clinical outcomes (i.e., therapy continued or discontinued, treatment success or failure, OAB-induced comorbidities) and costs for drugs and treatment of OAB-induced comorbidities (i.e., urinary tract infections, fractures, depression, and skin infections). Treatment success was defined as complete continence. A systematic MEDLINE literature search from January 1990-January 2006 identified English-language articles concerning the eight antimuscarinic drugs: darifenacin, solifenacin, trospium, immediate-release oxybutynin, extended-release oxybutynin, transdermal oxybutynin, immediate-release tolterodine, and extended-release tolterodine. Probabilities and cost data for these drugs were retrieved from the literature, and drug costs were based on 2005 average wholesale prices. The analysis was constructed from a payer's perspective. The time frame for the model was 3 months. RESULTS: Expected costs for each patient with OAB ranged from $3373 when treated with solifenacin to $3769 when treated with immediate-release oxybutynin. The average cost/patient with continued and successful treatment was lowest for solifenacin ($6863). Solifenacin dominated all other antimuscarinic agents because they were associated with high costs and low effectiveness. Success rates were the key parameters driving the sensitivity analysis. CONCLUSION: Among various antimuscarinic agents, solifenacin 5 mg had the lowest costs and highest effectiveness in the treatment of OAB.