INTERSTIM® SACRAL NEUROMODULATION AND BOTOX® BOTULINUM-A TOXIN INTRADETRUSOR INJECTIONS FOR REFRACTORY URGE URINARY INCONTINENCE: A DECISION ANALYSIS COMPARING OUTCOMES INCLUDING EFFICACY AND COMPLICATIONS

Purpose: Overactive bladder is a common disease for which current pharmaceutical treatment is often unsatisfactory.  Antimuscarinic medications have been the mainstay of treatment, but 1 year discontinuation rates are often >75% due to side effects.  Newer modalities, including Botox® and Interstim®, can be used when antimuscarinics are unsuccessful.  Our objective was to compare Interstim® and Botox® therapies for urge incontinence refractory to antimuscarinics.

Methods: A decision analysis model was constructed using values for efficacy and complications from the literature.  Markov state transition modelling was used with health states and transitions between states designed to fully account for the complex interplay of therapeutic efficacy and multiple possible complications.  Overall utility for the two operations was compared monthly for a period of 54 months, the average Interstim® battery life.  Multiple one-way sensitivity analyses for all utilities and outcome probabilities were performed.

Results: For every month during the simulation the overall utility value was higher for Botox® than Interstim®.  After 54 months cumulative utility was 3.86 vs. 3.74 favoring Botox® for an average yearly quality adjusted life year (QALY) value of 0.86 vs. 0.83.  All differences between the two surgeries were less than published minimally important differences (MID) for utilities.  Few meaningful threshold values were established supporting the robustness of our model results.

Conclusions: While Botox® has higher average QALYs at all time points, the differences are less than the MID.  Therefore, the two operations are highly comparable with similar overall utility.  Until appropriately powered randomized controlled trials are available, both operations are reasonable and effective strategies for the treatment of urge incontinence refractory to antimuscarinic therapy.  They have similar QALY outcomes when considering efficacy and complications.