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303 Outcomes of sacral nerve stimulation 15 Data collection and analysis For all patients meeting our inclusion criteria, we reviewed encounters at baseline prior to SNS initiation and at their most recent follow-up. Data are presented as medians and interquartile ranges for continuous data and as frequencies and percentages for categorical data unless otherwise specified. We compared patient symptoms, laxative and ACE usage, GSS, FIQL, and FISI at baseline and follow-up. McNemar's test and Wilcoxon signed-rank test were used for comparison as appropriate. We also compared outcomes between patients with and without concurrent fecal incontinence using Pearson's chi-squared test and Wilcoxon rank-sum test.  P -values less than .05 were considered statistically significant. Statistical analyses were performed using SAS 9.3 (SAS Institute, Inc., Cary, NC, USA) and SPSS (SPSS Statistics for Windows, Version 22.0, Armonk, NY, USA). RESULTS We included 25 patients in our study (52%male, median age at SNS initiation 10 years, range 6-19 years). All of the patients who completed the first stage procedure during the time period studied (between May 2012 and November 2013) went on to complete the second stage permanent implantation. At the time of data collection, patients had been treatedwith SNS for amedian of 2.3 years (IQR 2.1-2.7). Sixteen patients (64%) had functional constipation according to the Rome III criteria, six (24%) had a history of anorectal malformation, two (8%) had tethered spinal cord, and one (4%) had Hirschsprung's disease. 18 The indication for SNS treatment in all patients was severe constipation. Both patients with tethered spinal cord had undergone surgical detethering prior to SNS initiation, one undergoing detethering five years prior and the other two years prior. Both continued to have constipation despite either ACE treatment or an aggressive laxative regimen. The patient with Hirschsprung's disease had incomplete defecation and retentive fecal incontinence despite laxative treatment. At baseline, 18 patients (72%) had concurrent fecal incontinence, 14 (56%) had urinary incontinence, and two (8%) had urinary retention. Clinical symptoms As shown in Table 1, the majority of patients had three or more bowel movements per week at baseline, and this did not change significantly with SNS treatment at follow-up. However, the presence of both fecal incontinence and urinary incontinence decreased significantly after SNS treatment ( P < .01,  P = .04). Seventeen of 25 patients (68%) had >2 bowel movements and <1 episode of fecal incontinence per week at follow-up and therefore fulfilled our criteria for successful response. Ten of these 17 patients had functional constipation and the remaining seven patients had organic causes of constipation.