Baseline symptom severity and therapeutic success in a large prospective trial of sacral neuromodulation therapy for overactive bladder patients.

INTRODUCTION

The InSite trial is a prospective, multicenter post-approval study of subjects receiving sacral neuromodulation (SNM) therapy with the InterStim System. Enrolled subjects had bothersome symptoms of overactive bladder (OAB). The purpose of this analysis was to determine if severity of baseline symptoms had an impact on clinical outcomes.

METHODS

For device implant, therapeutic success was defined as a  ≥50% improvement in average leaks/day, or in voids/day or a return to normal voiding frequency. Groups were dichotomized into less versus more severe based on median number of leaks and voids. Subjects were grouped as less severe <2 leaks/day for UI; <11 voids/day for UF and more severe ≥2 leaks/day for UI;  ≥11 voids/day for UF. Therapeutic success at 12 and 24 months were compared between groups.

RESULTS

Three hundred and forty subjects completed test stimulation and 272 (80%) subjects received a full system implant. On average UI subjects had 1.3 leaks/day in the less severe group and 4.5 leaks/day in the more severe group. UI success rates were not statistically different between severity groups at 12 months or 24 months). At baseline, on average UF subjects had 9.4 voids/day for the less severe group and 15.1 voids/day for the more severe group. UF success rates were not statistically different between severity groups at 12 months or 24 months.

CONCLUSION

Data evaluating efficacy based on symptom severity demonstrates that SNM is effective in treating both less severe and more severely affected groups for both UI and UF at 12 and 24 months.