Sacral Neuromodulation for Refractory Bladder Pain Syndrome/Interstitial Cystitis: a Global Systematic Review and Meta-analysis

by | Oct 16, 2017 | Pain Management | 0 comments

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a common debilitating disease and there has not been consistently effective treatment. We aimed to evaluate all available literature regarding the efficacy and safety of sacral neuromodulation (SNM) for refractory BPS/IC. A comprehensive search of Pubmed, Web of Science and Cochrane Library through May 2016 was conducted. A total of 17 studies enrolling 583 patients were identified. Pooled analyses demonstrated that SNM was associated with great reduction in pelvic pain (weighted mean difference [WMD] −3.99; 95% confidence interval [CI] −5.22 to −2.76; p < 0.00001), Interstitial Cystitis Problem and Symptom Index scores (WMD −6.34; 95% CI −9.57 to −3.10; p = 0.0001; and WMD −7.17; 95% CI −9.90 to −4.45; p < 0.00001, respectively), daytime frequency (WMD −7.45; 95% CI −9.68 to −5.22; p < 0.00001), nocturia (WMD −3.01; 95% CI −3.56 to −2.45; p < 0.00001), voids per 24 hours (WMD −9.32; 95% CI −10.90 to −7.74; p < 0.00001) and urgency (WMD −1.08; 95% CI −1.79 to −0.37; p = 0.003) as well as significant improvement in average voided volume (WMD 95.16 ml; 95% CI 63.64 to 126.69; p < 0.0001). The pooled treatment success rate was 84% (95% CI 76% to 91%). SNM-related adverse events were minimal. Current evidence indicates that SNM might be effective and safe for treating refractory BPS/IC.

Bladder pain syndrome/interstitial cystitis (BPS/IC) is a chronic distressing disease, characterized by persistent or recurrent pelvic pain perceived to be related to bladder filling, associated with at least one other lower urinary tract symptom, without the evidence of a distinctively identifiable cause1. A recent report demonstrates BPS/IC is more common than previously thought, with a prevalence of 6.5% in adult females in the United States2. BPS/IC has a dramatic impact on patients’ quality of life3, 4. It often results in behavioral, emotional, psychological and even social problems4.

It has been reported that there are more than 180 treatments available for BPS/IC, but the results are usually varied5. It is estimated that 10% of patients with BPS/IC would progress to severe stage, refractory to conservative therapies6. The options to manage refractory BPS/IC include cystectomy with urinary diversion and bladder augmentation. Unfortunately, these interventions are associated with significant complications and often fail to alleviate the severity of pain7.

Sacral neuromodulation (SNM), introduced as a minimally invasive procedure in the 1980s, has previously been approved by the Food and Drug Administration to manage intractable overactive bladder symptoms and non-obstructive urinary retention8, 9. The transforaminal sacral afferent roots are stimulated by an implantable lead and electrode.SNM might also be a valuable option for patients with refractory BPS/IC. Several studies examining the effect of SNM in patients with refractory BPS/IC have been reported, but most included very few subjects and the results were conflicting10,11,12,13,14,15. Therefore, we systematically searched and analyzed published literature on the efficacy and safety of SNM in the treatment of refractory BPS/IC.

Figure 1Full size image
Flow diagram of studies included and excluded.

The main characteristics of the 17 studies are summarized in Table 1. BPS/IC was diagnosed using the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) criteria12, 14,15,16, 18, 24,25,26, or by clinical criteria and cystoscopic findings10, 11, 13, 17, 19, 21, 27. Two studies did not state their diagnostic criteria20, 23. All patients included in the study had failed conservative management, with a BPS/IC duration ranging from 3 to 9.1 years. All studies aimed to assess the efficacy and safety of SNM in the treatment of refractory BPS/IC. The participants were predominantly female (89%, 519 of 583) and the follow-up time ranged from test stimulation to 86 months.

Figure 2Full size image
Forest plot of pelvic pain measured by visual analog scale score (SD = standard deviation; IV = inverse variance method; CI = confidence interval).

One RCT and two prospective studies reported ICPI and ICSI scores12,13,14. Pooling the data of these three studies showed significant reduction in ICPI scores (WMD −6.34; 95% CI −9.57 to −3.10; p = 0.0001; Fig. 3) and ICSI scores (WMD −7.17; 95% CI −9.90 to −4.45; p < 0.00001; Fig. 4) following SNM.

Figure 3Full size image
Forest plot of the Interstitial Cystitis Problem Index (SD = standard deviation; IV = inverse variance method; CI = confidence interval).
Figure 4Full size image
Forest plot of the Interstitial Cystitis Symptom Index (SD = standard deviation; IV = inverse variance method; CI = confidence interval).
Figure 5Full size image
Forest plot of success rate (ES = effect size; CI = confidence interval).

Four studies12, 15, 18, 24 assessed daytime frequencies and two other studies assessed nocturia22, 26. Pooled analysis detected significant improvement in both daytime frequency (WMD −7.45; 95% CI −9.68 to −5.22; p < 0.00001; Fig. 6) and nocturia (WMD −3.01; 95% CI −3.56 to −2.45; p < 0.00001; Fig. 7). Pooling the data of six studies that reported voids per 24 hours demonstrated a significant difference favoring SNM (WMD −9.32; 95% CI −10.90 to −7.74; p < 0.00001; Table 2, Supplemental Fig. S1), consistent with the results of daytime frequency and nocturia12,13,14, 16, 22, 26.

Figure 6Full size image
Forest plot of daytime frequency (SD = standard deviation; IV = inverse variance method; CI = confidence interval).
Figure 7Full size image
Forest plot of nocturia (SD = standard deviation; IV = inverse variance method; CI = confidence interval).

Four studies assessing the efficacy of SNM, included analysis of urgency14,15,16, 18. Pooling the data from these four studies demonstrated a significant reduction in urgency (WMD −1.08; 95% CI −1.79 to −0.37;…

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