Objective: To assess the cost-effectiveness of solifenacin vs other antimuscarinic strategies commonly used in UK clinical practice, based on the results of a recent published review.
Methods: Overactive bladder (OAB) syndrome is characterized by symptoms of urgency, frequency, incontinence and nocturia. Pharmacological treatment comprises oral antimuscarinic agents, which are divided into older-generation treatments, including oxybutynin, and new-generation treatments, comprising solifenacin, tolterodine, darifenacin and fesoterodine. The latter have reduced central nervous system penetration and have better selectivity for the M3 subclass of acetylcholine receptors, resulting in improved tolerability. A recent systematic review and meta-analysis of the efficacy and safety of antimuscarinics provided an opportunity for an economic evaluation of these agents using a rigorous assessment of efficacy. A cost-utility analysis was undertaken using a 1-year decision-tree model. Treatment success was defined separately for urgency, frequency and incontinence, with efficacy data taken from the recent review. Treatment persistence rates were taken from the Information Management System database. Utility values for the calculation of quality-adjusted life-years (QALYs) were taken from published sources. The analysis included costs directly associated with treatment for OAB, i.e. antimuscarinic therapy, consultations with general practitioners, and outpatient contacts. Resource use was based on expert opinion. Costs were reported at 2007/2008 prices. Extensive deterministic and probabilistic analyses were conducted to test the robustness of the base-case results.
Results: Solifenacin was associated with the highest QALY gains (per 1000 patients) for all three outcomes of interest, i.e. urgency (712.3), frequency (723.1) and incontinence (695.0). Solifenacin was dominant relative to fesoterodine, tolterodine extended-release (ER) and tolterodine immediate-release (IR), and cost-effective relative to propiverine ER for urgency, frequency and incontinence. Solifenacin was not found to be cost-effective relative to oxybutynin IR for the frequency and incontinence outcomes, with an incremental cost-effectiveness ratio of > pound30,000/QALY threshold.
Conclusions: Solifenacin provided the greatest clinical benefit and associated QALYs for all three outcomes of interest across all therapies considered, and to be either dominant or cost-effective relative to all other new-generation agents, but not cost-effective relative to oxybutynin for frequency and incontinence.