Sacral neuromodulation (SNM) is a guideline-recommended treatment for overactive bladder (OAB) patients after conventional treatments have failed. Historically, the only commercially available SNM System was a primary-cell, non-rechargeable system with a device lifespan of 3-6 years, thus requiring multiple replacement surgeries over a patient’s life. Replacement surgeries increase patient surgical risk and healthcare costs.  Use of a rechargeable system that has a longer device life-span could significantly reduce or eliminate patient surgical risks and healthcare costs. The Axonics® miniaturized, rechargeable SNM (r-SNMTM) system is designed and tested to last for at-least 15 years and has regulatory approval in Europe, Canada and Australia. The RELAX-OAB study was a post-market clinical follow-up study in Europe designed to test the safety and efficacy of the Axonics r-SNM System. 1-Year follow-up results are presented here.

This prospective study treated 51 OAB patients across 7 European centers. Patients were implanted with the Axonics tined lead and IPG in a single procedure using a sacral transforaminal approach to implant the tined lead in proximity of the third or fourth sacral nerve. Voiding diaries (3-day) were completed at baseline and at post-implant follow-up visits. Data on patient quality of life was collected using the ICIQ-OABqol validated questionnaire. Patient reported data on satisfaction with treatment, ease of recharging and acceptability of recharging was also collected. In order to be comparable with the clinical literature for two-stage SNM treatment, the first month post-implant was considered as the “Test” period, and subjects were deemed to be Test Responders or Test Failures based on clinical outcomes at 2-week or 1-month visits. Responders were identified as patients that experienced 50% reduction in voids and/or incontinence episodes compared to baseline or a reduction in voids to less than 8 per day. All subjects were followed through the 1-Year follow-up regardless of their Test period outcome. Data analyzed per-protocol is presented.

A total of 38 females and 13 males with an average age of 51 years old (21-77 years) were implanted with the Axonics r-SNM System. At baseline patients had an average of 14.6 ± 6.1 voids per day and 9.6 ± 5.1 incontinence episodes per day.

34 of 51 (71%) subjects were Test Responders at 1-month post-implant. At 1-Year post-implant, 94% of the Test Responders continued to be therapy responders. Compared to Baseline, voids per day reduced by 6.5 (± 5.9, p<0.001, two-sided t-test), and leaks per day reduced by 6.6 in the Test Responders (± 4.1, p<0.001, two-sided t-test) (Figure 1).

Figure 1:  Bladder diary symptoms in Test Responders at baseline and at 1-year of r-SNM therapy.

Test Responders experienced clinically meaningful improvements in quality of life at 1-Year with average improvement from baseline in the composite Health Related Quality of Life (HRQL) score of 21.1 points (Figure 2). Improvements on all quality of life subscales were statistically significant and clinically significant (above the minimally important difference of 10 points [1]).

Figure 2. ICIQ-OABqol scores at baseline and 1-Year in Test Responders.

84% of the Test Responders were moderately or very satisfied with their r-SNM therapy.

Data on ease of recharging and acceptability of recharging was collected at 1-Year or 18-months. 90% of all implanted subjects responded that it was moderately or very easy to recharge their device and 97% thought the charging frequency and duration was moderately or very acceptable.

No serious device-related adverse events have been reported over 580 months of cumulative patient follow-up. Two patients were explanted, one due to a post-operative wound infection and one due to lack of efficacy. No issues or adverse events were reported related to device recharging.

The results confirm the 1-Year safety and sustained efficacy of the rechargeable Axonics r-SNM System. A rechargeable SNM system is expected to provide significant cost-effectiveness [2] and long-lived therapeutic benefits compared to existing non-rechargeable systems.

Patients implanted with the Axonics r-SNM System have received clinically significant improvements in their symptoms and quality of life at 1-Year post-implant. Patients reported that recharging their r-SNM system is easy and acceptable.

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Noblett K, Dmochowski R, Vasavada S, et al. (2017) Cost profiles and budget impact of rechargeable versus non-rechargeable sacral neuromodulation devices in the treatment of overactive bladder syndrome. Neurourol Urodyn 36: 727- 33