Study design, materials and methods
A prospective observational study was conducted between January 2023-January 2024 on 31 consecutive patients (25 females, 6 males; mean age 46.4, range 23 -78 years) who underwent implantation of Interstim X device in a tertiary referral centre. Efficacy data including quality of life measures and symptom severity scores were recorded. Successful outcome was defined as ≥50% reduction in urge urinary incontinence (UUI)/ urinary-frequency episodes for OAB and ≥ 50% reduction in need for self-catheterisation for NOUR. Adverse events and device-related complications were also collected.
Results
In our cohort, indications for implant included NOUR (n=20, 64.5%); refractory OAB (n=9, 29%) or both (n=2, 6.5%). (Figure 1). A total of 16 patients (52%) patients had exchange of Interstim II battery to Interstim X (for depletion) and 15 patients (48%) underwent a first stage trial (FST).
Overall, 29 patients (93.5%) responded to SNM therapy. One patient underwent explantation after FST due to inefficacy. One patient had a depleted Interstim II battery (implanted in South Africa) with return of OAB symptoms, who chose Interstim X for battery exchange but remained wet post-procedure.
In the cohort with NOUR (n=22), 19 (86.4%) patients required catheterisation prior to SNM therapy. Of these patients, 14 (74%) were catheter-free after implant, 4 (21%) had ≥50% reduction in need to self-catheterise and 1 (5%) remained catheter-dependent (and had the device explanted).
Figure 2 shows the outcomes of Interstim X (Medtronic™) recharge-free sacral neuromodulation (SNM) device for patients with NOUR.
There was no significant difference in their symptom severity score including urinary symptom profile (USP) (p=0.09). However, there was a significant difference in their urethral pain score on the visual analogue scale (p= 0.024) and quality of life measures (p<0.001). (Figure 3).
Of those with OAB, 10 (91%) had ≥50% reduction in UUI episodes/urinary frequency.
The mean Patients Global Impression of Improvement (PGI-I) score was 1.57 (range 1 – 3).
There were no reported intra-operative or device-associated complications. Post-operatively, 1 patient (3%) had a superficial wound infection and 2 patients (6.5%) reported stimulation-related discomfort.
Interpretation of results
Interstim X SNM device is effective and safe for both OAB and NOUR cohort of patients, with high success rates in improving their symptoms. Post-operative complications were minimal and transient.
In the NOUR cohort, Interstim X SNM therapy significantly improved their urethral pain and quality of life. Majority of patients were catheter-free after implant.
There were no reported compatibility issues in patients having battery exchange from a pre-existing Medtronic™ tined lead.
Concluding message
This study demonstrates that the Medtronic™ Interstim X device provides safe and effective SNM therapy for patients with both OAB and NOUR, with no device related complications identified in the short-term. Furthermore, most patients reported that they were “very much better” following implantation with the Interstim X device.
Notably, patients undergoing battery exchange with a pre-existing Medtronic™ tined lead in-situ experienced no compatibility issues.
However, to ensure sustained efficacy, further evaluation with longer follow-up is warranted to assess the durability of the observed high therapy response rates.