title: Sacral neuromodulation for nonobstructive urinary retention: a meta-analysis.
abstract: OBJECTIVE
  : The objective of this study is to systematically review the literature regarding the efficacy of sacral neuromodulation (InterStim) for treatment of nonobstructive urinary retention.
  
  
  METHODS
  : Eligible studies were selected through an electronic literature search of PubMed, Cochrane Collaboration, EMBASE, Web of Science and Scopus databases from January 1980 to August 2008. Two investigators independently reviewed all studies to assess methodological quality and inclusion criteria. Eligible studies evaluated sacral neuromodulation using implanted generators with permanent lead placement for treating nonobstructive urinary retention. The primary outcomes assessed were the change in pre- and postoperative postvoid residual and voided volume. Exclusion criteria were neurogenic etiology (ie, spinal cord injury) for urinary retention and non-English studies. The lead authors of all selected studies were contacted to identify ongoing or unpublished research, as was Medtronic, Inc. (Minneapolis, MN). Data were extracted from the selected studies and analyzed using RevMan 5 (Review Manager, Cochrane Collaboration, 2008). The mean difference with a 95% confidence interval was the effect of interest.
  
  
  RESULTS
  : A total of 14 articles met all inclusion criteria for the systematic review. This included one randomized control trial (RCT) and 13 observational studies. Outcome data was available from a total of 7 studies and used in the final analysis. After implantation, the mean difference in postvoid residual decreased 236 mL (95% CI: 219-253, P < 0.00001) and voided volume increased by 299 mL (95% CI: 280-318, P < 0.00001). The randomized control trial alone (n = 51) showed a mean decrease in postvoid residual volume in the implanted group compared with control of 270 mL (95% CI: 180-360, P < 0.00001) and a mean increase in voided volume of 104 mL (95% CI: 55-152, P < 0.0002).
  
  
  CONCLUSIONS
  : Based on the available literature, sacral neuromodulation is an effective therapy for treatment of nonobstructive urinary retention.
authors.affiliation: From the Departments of *Obstetrics and Gynecology, and †Emergency Medicine, University of Cincinnati, Cincinnati, OH.
authors.forename: Carey
authors.initials: C
authors.lastname: Gross
authors.forename: Mounira
authors.initials: M
authors.lastname: Habli
authors.forename: Christopher
authors.initials: C
authors.lastname: Lindsell
authors.forename: Mary
authors.initials: M
authors.lastname: South