Is repeat Botulinum Toxin A injection valuable for neurogenic detrusor overactivity-A systematic review and meta-analysis.

[AIM] To investigate the value of repeat botulinum toxin A (BTX-A) injections in patients with neurogenic detrusor overactivity (NDO).

[METHODS] We searched the PubMed, EMBASE, and EBSCO databases for articles published until June 2016. Studies that reported the efficacy and safety of repeat BTX-A injections for adult patients with NDO were eligible. The effect size for each outcome was calculated as the standardized mean difference ± standard error and 95% confidence interval, and was graded as small, >0.2; moderate, >0.5; or large, >0.8. The outcomes included maximum cystometric capacity (MCC), maximum detrusor pressure (MDP), reflex volume (RV), bladder compliance (BC), quality of life (QOL), and injection interval. Descriptive reviews were performed for urinary incontinence (UI) and adverse events (AEs).

[RESULTS] Eighteen studies involving 1533 patients whose level of evidence ranged from 3 to 4 were included in this study. We noted non-significant changes in MCC, MDP, RV, and BC between the first and last injections. Patients who had received ≤4 injections were found to have stable QOL improvements after the first and last injections, whereas patients who had received ≥5 injections were found to have a significant decrease in QOL after the last injection. No significant differences in injection intervals were noted after repeat BTX-A injections, and the repeat injection failure rate was low.

[CONCLUSION] Our study demonstrated that repeat BTX-A injections allow sustained improvements in patients with NDO. The rate of AEs was stable and low. However, additional high-quality, large-scale, and long-term trials are necessary to establish the efficacy and safety of ≥5 repeat BTX-A injections.