Introduction and hypothesis: The 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.
Methods: A 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.
Results: One 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]).
Conclusions: The 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.
Keywords: Neuromodulation; Overactive bladder; Therapeutics; Tibial nerve.