BARCELONA—Sacral neuromodulation (SNM) with Interstim Therapy is significantly better than an additional trial of standard medical treatment (SMT) for patients with refractory overactive bladder (OAB) who have not exhausted all possible medication options, investigators reported at the 43rd Annual Meeting of the International Continence Society (ICS).

In their study, improvements in efficacy and quality of life have been shown to last at least six months.

Tomas L. Griebling, MD, MPH, who is the John P. Wolf 33rd-Degree Masonic Distinguished Professor of Urology at the University of Kansas in Kansas City, presented six-month outcomes of a study comparing SNM with InterStim therapy versus SMT for the treatment of OAB.

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Interstim therapy uses a small implanted pulse generator connected to a quadripolar lead that transmits a low-level electrical impulse to the third sacral nerve root. The resultant neurostimulation decreases bothersome urinary symptoms without interfering with normal urination.

Dr. Griebling pointed out that while ICS guidelines currently recommend SNM as a third-line therapy for idiopathic OAB, a direct comparison of the effectiveness of SNM to SMT as second-line therapy has not been done.

The ongoing InSite OAB Trial includes patients with bothersome symptoms of idiopathic OAB including urinary urge incontinence (OAB wet) or urge frequency (OAB dry) who have failed or are unable to tolerate at least one anticholinergic or antimuscarinic medication AND have at least one anticholinergic or antimuscarinic medication that they have not yet tried.

This group represents a less severe segment of SNM-eligible patients than has been previously studied, Dr. Griebling said.

Patients stopped their OAB medications prior to and during baseline assessment and were randomized to SNM or SMT.  Individuals in the SNM arm underwent test stimulation and were implanted with SNM if successfully tested, while those assigned to the SMT arm resumed treatment with their prior OAB medication or started the next recommended medication.

Therapeutic success was defined as a 50% or greater reduction in the average number of leaks per day or a 50% or greater reduction improvement in voids per day or a return to normal voiding frequency (fewer than eight voids per day).

The analysis included 51 implanted SNM patients and 77 SMT patients. Most study participants were women, with a mean age of 58.7 years.

In the intent-to-treat (ITT) population, the therapeutic success rate was 61% for the SNM patients versus 42% for the SMT patients.  The ITT population included all randomized subjects, including 19 subjects who were randomized but not implanted.

In the as-treated population, the therapeutic success rates were 76% and 49% for the two treatment arms, respectively. The as-treated population included subjects with diary data at baseline and six months.

The SNM group also had statistically significant improvements in

quality of life measured by the widely validated, disease-specific  International Consultation on Incontinence Modular Quality of Life Questionnaire. The two groups did not differ significantly with respect to adverse events.

Dr. Griebling pointed out that SNM treatment is not suitable for patients with a spinal cord injury or spina bifida.  It is not yet known whether patients with neurologic diseases such as Parkinson’s disease and multiple sclerosis may benefit because such patients were excluded from the present trial. 

The study population will be followed for up to five years, he said.