Randomized clinical trials assessing third-line therapies to treat non-neurogenic overactive bladder syndrome: a review about methodology

Introduction and hypothesis Using similar methodologies and outcome measures is crucial to allow pertinent literature reviews and meta-analyses. Therefore, this scoping review aims to compare methodologies of randomized clinical trials (RCTs) assessing the efficacy of third-line therapies to treat non-neurogenic OAB: intradetrusor onabotulinumtoxinA (BoNTA) injections, sacral neuromodulation (SNM) and posterior tibial nerve stimulation (PTNS). Methods A literature search was conducted using the PubMed search database. Using filters, the search was limited to RCTs conducted on humans and written in English or French since 2000 which evaluated BoNTA injections, SNM and/or PTNS. RCTs focusing on pediatric or neurogenic OAB were excluded. For each included RCT, methodology was assessed using a standardized form investigating the study design, clinical outcomes and urodynamic outcomes. Inclusion criteria, sex ratio, blinding strategies, treatment arms, primary outcomes and delays for reevaluation were assessed. Availability of clinical and urodynamic outcomes was reported at baseline, 3 months and 6 months. Results Thirty-one RCTs were included in the final synthesis. The most frequent main outcome measure was change in the number of urinary incontinence episodes in 35.5% and in the number of voids per day in 25.8%. Bladder diaries were lacking in 12.9%, 32.3% and 80.1% at baseline, 3 and 6 months, respectively, while 26% of studies reported the results of urodynamic studies at any point. Conclusion Heterogeneity in study designs and data collection was pointed out between RCTs assessing the efficacy of third-line therapies to treat non-neurogenic OAB. We therefore advocate for the development of specific research guidelines focusing on OAB-related therapies.