The InSite trial was a prospective, multicenter post-approval study in subjects receiving sacral neuromodulation (SNM) therapy with the InterStim® System.  Enrolled subjects had bothersome symptoms of overactive bladder (OAB) including urinary urge incontinence (UI) or urgency-frequency (UF).  Limited information is available in literature about programming settings for subjects with OAB who receive SNM.  This analysis evaluated neurostimulator programming over long-term follow-up and reports patient programming at implant, 1-year, 3-years and 5-years.

Subjects with successful test stimulation received an SNM implant.  Neurostimulator programming throughout the duration of the trial was at physician discretion and this abstract reports programming parameters collected at the discharge of each visit from the time of full system implant through the 5 year follow-up for implanted subjects.  Subjects who reached each visit and had programming data available at the visit were included in the analysis.

Of the 340 enrolled subjects that completed test stimulation, 272 were implanted with InterStim. Mean age was 57 years and 91% were female.  At baseline, UI subjects had 3.1±2.7 leaks/day; UF subjects had 12.6±4.5 voids/day.  For those subjects who reported programming data at the visit, 36% (95/266) had the cycling feature turned on at implant; and 38% (89/236), 35% (64/183) and 30% (42/140) subjects had the cycling on at 1-year, 3-years and 5-years respectively. Table 1 describes programming parameters for amplitude, pulse width, and rate for the selected electrode configuration at implant and follow-up visits at 1 year, 3 years and 5 years. For amplitude, the median was 1.2v at implant and increased to 1.7v at 5 years. The majority of subjects changed amplitude from baseline to follow-up visits although the changes were minimal: 62.7%, 63.3%, 66.2% of subjects had their amplitude changed from baseline within 1v at the 1-year, 3-year, 5-year visit, respectively. Median for pulse width was 210µsec at implant and through follow-up visits; median for rate was 14 hz at implant and through follow-up visits.

The majority of subjects in the trial had therapeutic success and median thresholds that remained under two volts during the entire 5 years of observation.  Use of cycling was limited to about a third of all patients.

Data from this large study that is representative of a real-world patient population suggest that programming settings remain largely consistent from implant to 5 years post-implant.