Hypothesis / aims of study
The idiopathic overactive bladder syndrome is a bothersome medical issue for patients. Unfortunately, the treatment options mostly go along with bothersome side effects as well. Many patients’ withdrawal their treatment due to these side effects. Central neuromodulation is a well-established treatment option despite being an invasive procedure. In the past years peripheral neurostimulation has evolved as viable alternative. The percutaneous tibial nerve stimulation (PTNS) is a potential treatment option as first line treatment. The need for medical advice during this treatment and the placement of needles make it a complex procedure even in an outpatient clinic. The transcutaneous tibial nerve stimulation (TTNS) which use adhesive electrodes is less time consuming and can be used by the patients being at home.
We investigate the TTNS as potential conservative management in the treatment of overactive bladder syndrome in this clinical trial.
Study design, materials and methods
Our trial was designed as single-blind, randomized, prospective trial for patients with overactive bladder syndrome (OAB). We included patients, female, and male, with a non-neurogenic overactive bladder syndrome with no anatomical abnormalities of the lower urinary tract (eg. bladder outlet obstruction, pelvic organ prolapse). Improvement of symptoms reported by the patients and documented by questionnaires (PGI-I) were set as primary endpoint. Adhesive electrodes were attached to the N. tibialis posterior at the medial ankle. A stimulation of the N. fibularis superficialis (lateral ankle) was used as sham stimulation (placebo). The patient side was blinded. The patients were counseled to use the device 15 minutes each day of the week (20 Hz). There were trained by an expert for medical functional electrostimulation.
The statistical analyses were made by SPSS version 27. We used a chi-squared test for non-normal distribution or a two-sided t-test for normal distribution. For an estimated power of 95% in this setting a sample of 58 patients in each arm were calculated. We scheduled 18 months for recruitment.
Results
Overall, we included 82 patients (68 women, 14 men) in 18 months. There were no significant differences neither in the clinical meaningful endpoints of 24-hour frequency (placebo -1.94 vs. verum -1.27, ChiQuadrat p=0.2) , urgency urinary incontinence episodes in 24-hour (0.22 vs 0.22 , p=0.32) and nocturia (-0.27 vs. -0.16, p=0.76), nor in the validated questionnaires overactive bladder symptom score (OAB-SS) (-0.76 vs. 1.33 , p=0.18) ; International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form ICIQ-UI SF (-1.13 vs. -0.74 , p=0.48) or Patient Global Impression scale disease improvement (PIG-I) (2.47 vs. 2.54 , t-test p=0.72).
There were no side effects of the treatment reported by the patients.
Interpretation of results
To our knowledge this was the first single-blind, randomized and placebo-controlled trial to examine the efficiency of a transcutaneous tibial nerve stimulation contributed by an external stimulator. The TTNS were non superior to placebo. Despite this low efficiency patients did not regret the treatment because of its noninvasive with nearly no side effects. We missed the calculated sample size because of a high number of ineligible patients despite a great response with a big number of screened patients.
It should be mentioned that the improvement under sham stimulation was unexpected strong.