8 versus 12 weeks of percutaneous tibial nerve stimulation and response predictors for overactive bladder.

introduction and hypothesisThe primary objective is to compare weekly success rates after 8 vs 12 weekly percutaneous tibial nerve stimulation (PTNS) sessions for treatment of overactive bladder (OAB) in women and the secondary objective is to identify treatment response predictors.

methodsA retrospective study of 470 women was performed with the primary definition of success a Patient Global Impression-Improvement (PGI-I) score of 1 ("very much better") or 2 ("much better") and a ≥ 10-point improvement in both subscales of the Overactive Bladder Questionnaire-Short Form (OABq-SF). Additional analyses were performed to include a success definition of a PGI-I score of 3 ("a little better"). Categorical variables were compared using the Chi-squared test. Multivariate logistic regression was performed to identify factors associated with response.

resultsOne hundred and thirty-six out of 470 (29%) discontinued treatment before 12 weeks. One hundred out of 334 (29.9%) were successes at 8 weeks vs 138 out of 334 (41.3%) at 12 weeks (p = 0.002). Including a PGI-I score of 3 as an indicator of success, 181 out of 334 (54.2%) at 8 weeks and 202 out of 334 (60.5%) at 12 weeks were successes (p = 0.10). Factors associated with treatment response were neurological disorder (OR 4.32 [1.10-16.04]), prolapse surgery history (OR 3.89 [1.12-14.49]), and vaginal estrogen use (OR 1.76 [1.01-3.08]). Recurrent UTI was associated with failure (OR 0.42 [0.21-0.86]).

conclusionsThe PTNS treatment success rate for OAB in women is greater at 12 weeks than at 8 weeks based on two validated questionnaires, the PGI-I and the OABq-SF. However, the success rates were equivalent if women who are "a little better" are also considered successes; with this definition, clinicians may consider shortening treatment duration to 8 weeks. Four clinical factors were significantly associated with response and may help to guide patient selection.