Nerve stim device provides long-term OAB symptom improvement

An investigational wireless, implantable tibial nerve stimulator is safe and provided improvement in overactive bladder (OAB) symptoms over 3 years of follow-up, updated results of a prospective, multicenter international trial suggest.

A majority of patients had a 50% or greater improvement in number in OAB symptoms versus baseline, according to study investigator Alex Digesu, MD, PhD, of St. Mary’s Hospital, Imperial College of London.

No serious adverse events were reported during the 3-year follow-up of patients implanted with the device (RENOVA iStim), Dr. Digesu said at the International Continence Society annual meeting in Philadelphia.

"The treatment can be tailored individually, and we are able to demonstrate with this study there is a significant short- and long-term improvement of the overactive bladder symptoms," Dr. Digesu told attendees in a podium presentation.

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This is the first long-term study of an implantable tibial nerve stimulation device for the treatment of refractory overactive bladder symptoms, he added.

The original pilot study for the device, known as the OPTIMIST trial, included 36 patients with refractory OAB symptoms who were recruited and followed for 6 months after the device was activated.

Top-line results of that study, published in Neurourology and Urodynamics (2017; 37:1060-7), showed that more than 70% of patients had clinical improvement 6 months after device activation.

The long-term follow-up results, presented at the ICS meeting, included 20 of those pilot study patients who were followed for 3 years.

Dr. Digesu reported that the clinical improvement was durable, with 75% of the patients (16/20) reporting a 50% or greater reduction in urgent voids or leaks, or normalization of voids at 36 months.

Durable long-term effects were also achieved in relief of urinary incontinence, according to Dr. Digesu. Clinical success, defined as a 50% or greater reduction in leaks, was documented for 52% of the patients in the pilot study at 6 months, and in 58% of the patients in the follow-up study at 36 months.

Looking at severity levels, about 80% had a reduction of 50% or greater in large leaks, characterizing urge incontinence, as opposed to small volume leaks that characterize stress incontinence, he said.

Next:70% had clinically meaningful QoL improvementSeventy percent of patients had clinically meaningful improvements in quality of life, as measured by a validated, OAB-specific quality of life questionnaire, he added.

One patient in pilot study had a suspected wound infection that resulted in device explantation, Dr. Digesu said, while other adverse events were mild and short lasting, and included pain at the insertion site.

There were no surgical revisions or device failures in the long-term follow-up, he added.

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The miniature implant used in the study is powered by an external control unit that patients wear around the leg for 30 minutes daily. By stimulating the tibial nerve, the device modulates neuronal signals to the bladder, pelvic floor and urinary sphincter, according to Dr. Digesu.

About 60% of the devices were implanted under local anesthesia, according to Dr. Digesu, who told attendees that he used local anesthesia in all 12 of the patients he enrolled in the study.

“This was well tolerated, and allowed the patient to leave the room straight after the procedure,” he said.

Data from the current investigations need to be confirmed in a larger multicenter international study, according to Dr. Digesu.

BlueWind Medical provided funding for the study. Dr. Digesu reported disclosures related to Medtronic and BlueWind Medical.