The aim of this review was to compare the 6 months outcomes and side effects of sacral nerve stimulation (SNS) and botulinumtoxin A (Botox) injection for refractory overactive bladder (OAB) .

Search strategy: PubMed and EMBASE were searched using the search terms ‘‘Botulinum Toxin A’’, “Sacral nerve stimulation”, ‘‘ refractory overactive bladder syndrome”. The conference abstracts and some other content-independent articles were not included in this systematic review. We combined the search results and removed duplicate articles in order to obtain an initial set of potentially eligible studies.Study inclusion criteria: Studies were considered eligible if they met all the following inclusion criteria: (1) The type of studies should be a randomized trial (2) All participants in each study should be women with refractory OAB (3) As for the outcome ,a study report included: a. The OAB clinical symptoms improved. Conditions (such as the change in urgency frequency .(4)As for the controls, should us SNS to treat refractory OAB ,another group should us Botox-A treatment.Study exclusion criteria：（1）If the necessary data were extrapolated from the reported outcomes (2)If the outcomes of interest were not described evidently（3）If patient with UTI.Data extraction: Articles after removing duplicate were assessed independently by two authors for possible inclusion. They also extracted data on first author, publication year, patients sources, study size, mean age of patients, follow-up times. Statistical methods: All calculations and data manipulations were performed using RevMan 5.3 (Cochrane Collaboration, Oxford, UK). Survival data were log-transformed and pooled results were expressed in terms of the log(OR) and standard error of the log(OR) .The Begg's test was performed and funnel plots were generated in STATA 13.0 (STATA Corp., College Station, USA) to assess the potential publication bias; p>0.05 was interpreted to indicate the absence of significant publication bias.

There were 80 studies（all studies were in English databases）identified based on a defined search strategy.66 studies were excluded by screening the title and abstract，leaving 14 studies for further evaluation. After reviewing the complete manuscript of each included studies. Finally 2 studies were eligible for systematic review after critical evaluation. All of the two studies were published in English Two trails enrolling 330 patients（SNS group=164；Botox-A group=166）reported the changes in OAB symptoms After SNS intervention. Our results indicated women with refractory OAB receiving sacral nerve stimulation (SNS) gained a greater improvement than botulinumtoxin A (Botox) injection[risk ratio(RR)0.91，95% CI 0.45-1.85]. The failure rate Botox –A group was higher than SNS group [risk ratio(RR)1.60，95% CI 0.27-9.41].Two trials with total of 474 patients（SNS group=243；Botox-A group=230）reported the complication after these two treatment . The pooled results showed significantly lower complication rate after SNS than Botox-A[risk ratio(RR)2.90，95% CI 2.00-4.21].

In total，2 studies with 853 patients were included. Our results indicated women with refractory OAB receiving sacral nerve stimulation (SNS) gained a greater improvement than botulinumtoxin A (Botox) injection[risk ratio(RR)0.91，95% CI 0.45-1.85].The failure rate Botox –A group was higher than SNS group [risk ratio(RR)1.60，95% CI 0.27-9.41].The complication rate ，such as urinary tract infection（UTI），was lower in SNS group than in Botox-A group[risk ratio(RR)2.90，95% CI 2.00-4.21].

The SNS resulted in lower failure rates at 6 months when performed for refractory OAB symptoms as compared with the Botox procedure. And the SNS resulted in lower complications at 6 months when performed for refractory OAB female patients as compared with the Botox-A procedure. However, further studies are needed to evaluate the long-term cost- effectiveness of both procedures.