To determine the long term safety and performance of a novel implantable tibial neurostimulation device (the BlueWind Medical RENOVA iStimTM System) for the treatment of OAB.

A wireless peripheral neurostimulator device (BlueWind Medical Ltd.) was implanted on the posterior tibial nerve approximately 5 cm above the medial malleolus and 2 cm posterior to the tibia in patients with refractory OAB. Local anaesthesia was used unless general anaesthesia was clinically indicated. The implant that electrically stimulates the tibial nerve is wirelessly powered by an external control unit (ECU). The ECU controls the therapeutic parameters and is worn by the patient during a specified treatment period whilst at home. A Physician Programmer is also used to remotely set individual stimulation parameters for each patient to optimize therapeutic outcome. 
Refractory OAB patients with symptoms of urinary frequency greater than 8 times/24 hours and/or urinary urgency leaks of at least 2 leaks/24 hours (both male and female) were enrolled, while those with clinically predominant stress urinary incontinence or those suffering from any neurological disease or disorder were excluded The efficacy and safety of BlueWind Medical RENOVA iStimTM system were assessed using a 3 day frequency volume chart, quality of life questionnaire (OAB-q) as well as clinical examination for up to 36-months post activation. The McNemar's test for paired proportions was applied to compare to the clinical improvement (i.e. ≥50% improvement in either number of urge-related incontinence episodes or number of urgent voids) at 6-months with that of longer follow-up periods.

A total of 36 patients were recruited for the original pilot study and were followed for 6 months post activation of the device. All 36 patients were implanted successfully with mean procedure duration of 34.8 minutes. These results have been previously reported.
Twenty-three OAB RENOVA iStim system implanted subjects were re-enrolled for the extended, 3-year follow-up study.  Up to date, 11 patients have reached 30-months follow-up. No SAEs were reported during the extended follow-up. In the per-protocol analysis, 9 of the 11 patients (82%) have shown more than 50% improvement in either number of urge-related incontinence episodes or number of urgent voids as compared to baseline. In the intent-to-treat analysis, 18 out of the 23 patients have shown above 50% improvement (78%).  
By August 2018, all of the patients are expected to reach their 36-month follow-up visit and final results will be presented.

BlueWind Medical RENOVA iStim system demonstrates long term safety and efficacy. When comparing the results of the long term follow-up to the 6-months follow-up, responders’ rates were similar at 6- and 30-months follow-up periods (74% and 78%, respectively).

The BlueWind Medical RENOVA iStim System for the treatment of OAB demonstrates safety as well as sustainable successful efficacy long-term results. A larger multicentre, international study is planned to confirm these promising preliminary data.