Cost-effectiveness of test phase implantation strategies for InterStim® sacral neuromodulation

Sacral neuromodulation with InterStim can be performed with staged implants or peripheral nerve evaluation followed by a combined stage I/II procedure. In both, unilateral or bilateral leads can be placed for the testing phase. Our objective was to determine the cost-effectiveness of these strategies in patients with refractory overactive bladder.

A cost-effectiveness model compared 6 strategies, namely, unilateral and bilateral testing for both stage I and peripheral nerve evaluation, combined stage I/II, and no treatment. Costs were derived from a societal perspective using Medicare physician fee schedules and published studies. Quality-adjusted life-years (QALYs) were assigned using utility values. Results were reported using incremental cost-effectiveness ratios. Model robustness was assessed using probabilistic sensitivity analysis. Monte Carlo analysis sampled statistical distributions for each variable to examine the effects of varying all values simultaneously.

No InterStim treatment was the least expensive but also the least effective option. Unilateral and bilateral stage I were the only cost-effective options with incremental cost-effectiveness ratios of $3533 and $7600, respectively. Because bilateral stage I was more effective, it is preferred. Probabilistic sensitivity analysis showed bilateral stage I was most likely to be cost-effective at willingness-to-pay thresholds greater than $6000 per QALY. At lower thresholds, no treatment was more economically acceptable.

Bilateral and unilateral stage I lead placement were the only cost-effective strategies. Bilateral stage I was preferred due to greater effectiveness. In probabilistic sensitivity analysis, bilateral stage I was the most likely cost-effective strategy at all willingness-to-pay thresholds greater than $6000 per QALY confirming model robustness.