A randomized trial comparing neuromodulation with percutaneous tibial nerve stimulation to sham treatment for accidental bowel leakage - The notable trial

Objective: To determine if percutaneous tibial neural stimulation (PTNS) is superior to sham stimulation for treatment of refractory accidental bowel leakage (ABL) in women. Methods: A multicenter, randomized superiority trial was conducted with a 28‐day run‐in phase during which subjects completed a minimum of two 7‐day bowel diaries to account for potential journaling effect on ABL. Eligibility for enrollment and post run‐in randomization included =12 points on St. Mark's (Vaizey) scale; prior supervised pelvic muscle training for ABL; inadequate response, intolerance or unwillingness to try constipating medication; and demonstrated adherence to diary completion during the run‐in. Women with severe constipation or uncontrolled diarrhea (Bristol Stool Form types 1 and 7) over the preceding 3 months were excluded. Assignment was 2:1, PTNS v validated sham treatment with 30‐minute, weekly stimulation sessions. Participants were masked to intervention group. The primary outcome was change from baseline in St. Mark's score after 12 weeks of stimulation, analyzed by intention to treat (ITT). Secondary outcomes included variables recorded in a 14‐day bowel diary smartphone application, condition‐specific quality of life (QOL), and Patient Global Impression of Improvement (PGI‐I). A general linear mixed model, adjusting for site, visit, and treatment by visit interaction, was used to compare the efficacy of PTNS and sham. The published minimally important difference (MID) for the St. Mark's score is 5 (1). The trial had 90% power to detect a difference of 4 points between groups for change from baseline in St. Mark's score after 12 weeks of treatment, with a target sample size of 147, inflated to 165 for potential 10% drop‐out. Results: 166 women were randomized (111 PTNS, 55 sham). Mean age 64 (±12) years, 81% were White, 11% Black, and 10% Latina. Mean BMI was 29 (±7). The PTNS group did not demonstrate a greater improvement in St. Mark's scores after 12 weeks of stimulation compared to the sham group (‐5.3 vs.‐3.9 points, adjusted difference [95% confidence interval]‐1.3 [‐2.8, 0.2]). Weekly frequency of diary documented bowel events did not differ significantly between groups (Table). Condition‐specific QOL measures and PGI‐I scores did not indicate a benefit of PTNS over sham. Conclusions: Though the improvement in St. Mark's score after 12 weekly sessions of PTNS exceeded the MID, PTNS did not result in significantly greater ABL symptom reduction, incontinence events or QOL compared to sham stimulation.