RESUMO
INTRODUCTION AND HYPOTHESIS: Electrical nerve stimulation is a widely used treatment for overactive bladder but there is no consensus regarding the best placement of electrodes or protocols. We hypothesised that some non-implanted neurostimulation protocols would be more effective compared to others for treating urinary symptoms and improving quality of life among adults diagnosed with non-neurogenic overactive bladder. METHODS: A systematic review and meta-analyses of randomized clinical trials were performed in five electronic databases: PubMed/MEDLINE, Lilacs, CINAHL, Web of Science, and PEDro. The main outcome was urinary symptoms-frequency, nocturia, and urgency-and the secondary outcome quality of life. Some protocol characteristics were extracted, e.g., frequency, pulse width, intensity, intervention time, and electrode placement. RESULTS: Nine randomized controlled trials were included. Tibial neurostimulation showed better results than sacral neurostimulation for urge incontinence (mean difference = 1.25 episodes, 95% CI, 0.12-2.38, n = 73). On the pooled analysis, the different neurostimulation protocols-intravaginal, percutaneous tibial, and transcutaneous tibial nerve stimulation-demonstrated similar results for urinary frequency, nocturia, and urgency as well as quality of life. In general, effect sizes from meta-analyses were low to moderate. The best reported parameters for percutaneous tibial nerve stimulation were 20-Hz frequency and 200-µs width, once a week. CONCLUSIONS: There was evidence that tibial neurostimulation is more effective than sacral neurostimulation for urge incontinence symptoms among patients with non-neurogenic overactive bladder. Overall, there was no superiority of an electrical nerve stimulation electrode placement and protocol over others considering urinary symptoms and quality of life. Further studies with three-arm trials are necessary. This study was registered at PROSPERO: CRD4201810071.