Sacral nerve stimulation for refractory OAB and idiopathic urinary retention: Can phenotyping improve the outcome for patients: ICI-RS 2019?

AIMS: Sacral nerve stimulation (SNS) is widely used to treat refractory idiopathic overactive bladder (OAB) and idiopathic urinary retention. However, clinical outcomes are variable and understanding predictive factors for success or side-effects would enable personalization of therapy and optimization of outcomes. At the International Consultation on Incontinence-Research Society meeting 2019, a Think Tank was convened to discuss how advances in the basic science study of SNS may be translatable into clinical practice to improve outcomes of patients undergoing SNS treatment. METHODS: We conducted a literature review and expert consensus meeting focusing on current methods of phenotyping patients and specifically, how advances in basic science research of the mechanism of action of SNS can be translated into clinical practice to improve patient selection for therapy. RESULTS: The terms "Idiopathic OAB" and "idiopathic urinary retention" encompass several underlying pathophysiological phenotypes. Commonly, phenotyping is based on clinical and urodynamic factors. Animal studies have demonstrated that high-frequency stimulation can produce rapid onset, reversible conduction block in peripheral nerves. Altering stimulation parameters may potentially enable personalization of therapy depending upon the clinical indication in the future. Similarly, advances in conditional and closed-loop stimulation may offer greater efficacy for certain patients. Phenotyping based on psychological comorbidity requires further study to potentially optimize patient selection for therapy. CONCLUSIONS: Idiopathic OAB and idiopathic urinary retention are heterogenous conditions with multiple potential underlying phenotypes. Tailoring stimulation parameters to the needs of each individual according to phenotype could optimize outcomes. Assessing psychological comorbidity may improve patient selection. Areas for further research are proposed.

The Value of Ambulatory Urodynamics in the Evaluation of Treatment Effect of Sacral Neuromodulation.

OBJECTIVES: To assess the improvement of symptoms by sacral neuromodulation (SNM) in an objective way by carrying out an ambulatory urodynamic study (ambulatory-UDS). Until now, successful treatment has been defined as a ≥50% improvement recorded on voiding diaries. Voiding diaries are a patient reported outcome tool. A tool with less bias is desired to evaluate the treatment results before an expensive permanent system is implanted. METHODS: Between 2002 and 2015, a total of 334 patients with lower urinary tract symptoms were included consecutively in an ambulatory-UDS database. From this database, a subgroup of patients was selected which underwent SNM. RESULTS: In 51 patients, an ambulatory-UDS was performed both at baseline and during the SNM test period. A positive treatment outcome after test stimulation based on the patients' voiding diary, correlated (p < 0.0001) with an improvement on ambulatory-UDS. Twenty-six of the 30 patients, who have showed improvement of more than 50% on voiding diary parameters and who had subjective improvement of their symptoms, showed an early improvement on ambulatory-UDS. CONCLUSIONS: Ambulatory-UDS can be used in clinical decision making, as it is associated with voiding diary improvement during the SNM test period. Using ambulatory-UDS to confirm success could in the future justify the shortening of the test period.