This is the first report of clinical performance and safety of the rechargeable InterStimTM Micro sacral neuromodulation (SNM) system in subjects with non-obstructive urinary retention (NOUR). Sacral Neuromodulation (SNM) is an advanced therapy option for NOUR, overactive bladder, and fecal incontinence, with both primary cell and rechargeable devices available. While there is long-term data available for SNM in all indicated conditions, the volume of publications for NOUR is smaller than for the other indications. The ELITE study is an ongoing global, prospective, post-market study to confirm the clinical performance and safety of the rechargeable InterStim Micro SNM system in all indicated conditions.

Eligible NOUR subjects (with an elevated post-void residual (PVR) persistent for ≥6 months and ≥5 clean intermittent self-catheterizations (CISC) on a 7-day voiding diary) were enrolled following successful therapy evaluation and neurostimulator implant. Subjects completed voiding diaries and questionnaires at baseline and 3-months follow up. The primary objective was improvement in the number of CISC per day at 3 months post-implant compared to baseline. Patient Global Impression of Improvement (PGI-I) was collected on a scale from 1 (very much better) to 7 (very much worse); categories were collapsed to better, neutral, worse for reporting. Patient satisfaction was collected on a 5-point scale from “very satisfied” to “very unsatisfied”; categories were collapsed to satisfied, neutral, unsatisfied. Patient recommendation was collected on a 5-point scale from “definitely yes” to “definitely not”; categories were collapsed to yes, neutral, no. Safety was evaluated by collection of reportable adverse events (AE), which were classified by MedDRA System Organ Class (SOC) and Preferred Term (PT). Data are reported as mean ± standard deviation or with 95% confidence intervals (CI).

Of 27 subjects enrolled in the NOUR cohort and implanted with InterStim Micro, most were female (96.3%). The mean age was 43±17.9 years and BMI was 27±5.9 kg/m2. At baseline subjects had a mean of 5.6±2.3 CISC per day. At the 3-month follow up, the mean number of CISC per day was 2.07±3.3 (Figure 1, n=23), with a mean change from baseline of -3.52 (95% CI: -4.77, -2.26) (p≤0.001).  Mean post-void residual (PVR, in mL) was 368 ± 241 at baseline and 104 ± 155 at 3 months, with a mean reduction in PVR of 277± 243 at 3 months vs baseline. On the Patient Global Impression of Improvement (PGI-I), 88% of subjects reported their condition was better at 3-months compared to baseline (Figure 2). Eighty-four percent (84%) of subjects reported they were satisfied with how this therapy impacted their symptoms, and 84% said they would recommend this therapy to patients suffering from similar symptoms (Figure 2). 

Device-, procedure-, or therapy-related AEs occurring in more than 5% of patients included implant site pain (11.1%; 3/27) and medical device site discomfort (7.4%; 2/27). There was one related serious AE of infection which led to system explant and was resolved. There were no unanticipated adverse device effects.

These results confirm the safety and clinical performance of InterStim Micro for subjects with NOUR by demonstrating a statistically significant decrease in the number of CISC per day (mean change of -3.52, p≤0.001), a high proportion of patients reporting symptom improvement (88% of patients) and satisfaction with the therapy (84% of patients), and a safety profile that is within the range of previously reported data for SNM. These data add to the established evidence base for SNM therapy and provide specific evidence for the smallest rechargeable SNM device, which represents an important option for patients who may need or prefer a smaller device. Follow-up of enrolled patients is ongoing.

To our knowledge, this is the first report of post-implant results from any rechargeable SNM system in patients with NOUR. These data confirm the clinical performance and safety for a rechargeable SNM device through 3-months post implant for subjects with NOUR.

Continence 7S1 (2023) 100934
DOI: 10.1016/j.cont.2023.100934