Hypothesis / aims of study
Sacro neuromodulation (SNM) is a guideline recommended therapy indicated in patients with refractory OAB, nonobstructive urinary retention and fecal incontinence. SNM via an implanted stimulator has shown good response rates in patients with OAB, with at least 50% improvement in symptoms in an estimated 67-87% of patients. We hypothesized that the basic properties of the bladder found in the urodynamic study could help predict the success rate of SNM. Therefore, in this study, we evaluated factors associated with successful SNM after implantation for the treatment of medication refractory overactive bladder (OAB). Six-month results are presented.
Study design, materials and methods
A total of 35 eligible patients undergoing treatment for refractory OAB at tertiary center between 2018-2019 were prospectively enrolled. All patients were implanted with a tined lead and the SNM (Medtronic, Inc., Minneapolis, MI, USA) in a staged procedure. All patients underwent urodynamic study two weeks before SNM. Efficacy data were collected using a 3-day bladder diary with urgency profile, the validated OABSS (Overactive Bladder Symptom Score) questionnaire. Therapy responders were identified as participants with a 20% or greater reduction in frequency or urgency episodes compared to baseline. We also evaluated prognostic factors of SNM by analyzing urodynamic parameters.
Interpretation of results
SNM is a very effective treatment as a third line therapy and actually has a high response rate. We further analyzed UDS factors that influence the success rate of SNM. As a result, it was confirmed that bladder compliance and response rate had a negative correlation. This suggests that if patients have lower compliance, they are highly unlikely to have a successful SNM trial. In particular, patients with low compliance, particularly below 8.3, should be counseled that their SNM tiral is unlikely to be successful.