Hypothesis / aims of study
Progression from sacral neuromodulation (SNM) test stimulation (Stage 1) to permanent implantation (Stage 2) is a key clinical decision point in refractory interstitial cystitis/bladder pain syndrome (IC/BPS), yet reported conversion rates vary and comparisons between percutaneous nerve evaluation (PNE) and staged tined-lead testing are inconsistent.
Study design, materials and methods
We registered the protocol in PROSPERO (CRD420261286234) and conducted a PRISMA-guided systematic review of MEDLINE (PubMed), Embase, and Web of Science. Adult IC/BPS cohorts undergoing SNM test stimulation via PNE or staged tined quadripolar lead trials were eligible. Random-effects meta-analysis of proportions was performed with prespecified subgroup analyses by test strategy and mixed-effects meta-regression in staged studies using data source (claims vs clinical) as moderator.
Results
Seventeen studies contributed 24 cohorts (11 PNE-only, 10 staged-only, 3 mixed). The pooled Stage-1 to Stage-2 conversion was 64% (95% CI 56–72).In non-mixed cohorts, conversion was 53% for PNE (95% CI 47–59)and 76% for staged trials (95% CI 59–87), with significant subgroup differences (p=0.0036). In staged studies, clinical cohorts showed higher conversion than claims-based cohorts (80% vs 45%); claims data were associated with lower odds of progression (OR 0.19, 95% CI 0.05–0.76; p=0.0217).
Interpretation of results
We found an overall conversion rate of approximately 64% for IC/BPS patients who undergo a trial stimulation ultimately receive a permanent implant. Notably, the type of test significantly influenced outcomes. Patients undergoing a staged tined-lead trial had a substantially higher conversion rate of about 76% compared to those receiving PNE 53%. This indicates a roughly 20 percentage-point absolute increase in success when using the two-stage tined-lead approach.
Our meta-regression revealed a pronounced design effect in staged test strategy studies, utilizing claims databases which reported significantly lower about one-fifth the odds compared to clinical trial cohorts suggesting that claims data may systematically under capture successful trials due to billing-based outcome definitions or incomplete follow-up.