OBJECTIVES: Overactive bladder syndrome (OAB) affects 17% of the US population and significantly reduces quality of life (QoL). For patients failing initial behavioral therapy and pharmacotherapy with antimuscarinics, neuromodulation therapy such as percutaneous tibial nerve stimulation (PTNS) may improve symptoms. This systematic review and meta-analysis aims to determine the efficacy of PTNS in the treatment of OAB by examining its effect on urinary frequency and QoL.
METHODS: We searched Medline (1948 to December 2010) for randomized controlled trials (RCTs) and cohort studies. Inclusion criteria were full text articles in the English language investigating adults with a primary diagnosis of OAB who were treated with PTNS. Exclusion criteria included patients previously treated with PTNS, or OAB caused by chronic pelvic pain, interstitial cystitis, and neurogenic etiologies. Using the MetaAnalyst software (3.13, Tufts Medical Center, Boston), we performed a random effects meta-analysis by pooling data across RCTs and cohort studies and tested for statistical heterogeneity with I 2. For changes in voiding frequency, we calculated the weighted mean difference in voids per 24 hours, and during daytime and nighttime. For QoL in the RCTs, we calculated the standardized mean effect size (mean difference divided by standard deviation). For the cohort studies we pooled QoL data from different questionnaires by using Fisher's method to combine the p-values for each study.
RESULTS: Our literature search yielded 1182 abstracts, which resulted in 3 eligible RCTs (n=278) and 9 cohort studies (n=380). Over 74% of patients were female with mean ages ranging from 45 to 68 years. Half of the studies followed the standard PTNS protocols (one 30-minute session weekly for 12 weeks); other studies had weekly sessions <12 weeks or for an unspecified duration, or triweekly sessions for 4 weeks. Some cohort studies reported only daytime or nighttime voiding frequency. QoL questionnaires varied and included the Incontinence QoL (I-QoL), Incontinence Impact (IIQ-7), OAB (OAB-q), SEAPI for incontinence, and SF-36. Based on 3 RCTs, PTNS compared with placebo significantly reduced the number of voids per 24 hours by -1.7 (95% CI -3.1 to -0.3). For cohort studies, PTNS reduced voids from baseline to follow-up by -2.8 (95% CI -3.9 to -1.8) over 24 hours, by -3.2 (95% CI -4.4 to -1.9) for daytime voids, and by -1.3 (95% CI -1.7 to -0.8) for nighttime voids. Across studies using diverse instruments, the summary standardized mean difference in QoL comparing PTNS with placebo was 1.0 (95% CI 0.2 to 1.8). In the cohort studies, QoL was improved from baseline to follow-up by 4.7 (95% CI 2.8 to 6.7) points for the SF-36. For incontinence-specific QoL using Fisher's method, improvement in the QoL from baseline to follow-up was significant (p<0.001). Moderate to significant statistical heterogeneity (I 2 from 60% to 80%) existed for all results except daytime and nighttime voids and SF-36.
CONCLUSIONS: This systematic review and meta-analysis suggests that PTNS for the treatment of OAB significantly reduces urinary frequency and improves QoL. This office-based, minimally invasive procedure may be a favorable option for patients with refractive OAB.
