Hypothesis / aims of study
Overactive bladder (OAB) syndrome is a common condition. In patients with refractory OAB, electrical stimulation—either with surface electrodes (TENS) or percutaneous needles (PTNS)—offers a therapeutic alternative. Several studies support the need for maintenance therapy to sustain symptom improvement [1].
This requirement for continuous in-clinic maintenance may impose a healthcare burden. If similar efficacy were demonstrated with TENS, patients could perform maintenance therapy at home [2].
The aim of this clinical trial was to demonstrate that there are no significant differences in clinical efficacy between TENS and PTNS.
Study design, materials and methods
We conducted a randomized, prospective, single-center, double-blind, parallel-arm clinical trial, (IRB: 2022-598-1). Patients with OAB refractory to pharmacological treatment were included. All participants provided informed consent and were randomly assigned (using sealed envelopes) to either the PTNS or TENS group.
PTNS and TENS therapies were blinded to the patient with a special devised cover, both groups receiving needle puncture and two pads. Treatment consisted of twelve weekly 30-minute sessions using stimulation parameters of 1–10 mA, a frequency of 20 Hz, and a pulse width of 200 µs. Sample size was calculated for non-inferiority (power 80%, one-sided α=0.05), assuming responder rates of 79% (reference) and 65% (experimental), with a 20% margin. A total of 46 patients were required (including 5% dropout).
Clinical efficacy was assessed using the OABq-SF questionnaire and bladder diaries. Responders were defined as those achieving a ≥7-point improvement in the symptom subscale and ≥11-point improvement in the quality-of-life subscale [3]. Patient satisfaction was evaluated using the Treatment Benefit Scale (TBS) questionnaire.
Results
A total of 50 patients were enrolled: 23 in the TENS group and 27 in the PTNS group. The mean (SD) age was 56 (15.4) years, and the median disease duration (IQR) was 21.5 (31) months. The cohort included 39 women (78%) and 11 men (22%), with 6 patients (12%) diagnosed with diabetes. No significant differences at baseline characteristics were observed between groups (Table 1).
Both groups showed significant improvement in OABq-SF symptom (TENS −10.7, p=0.001; PTNS −11.7, p=0.001) and quality of life scores (TENS +11.5, p=0.011; PTNS +11.8, p=0.003), with no significant differences between-groups. Treatment satisfaction was similar (TENS 69.6% vs PTNS 63%).
Bladder diary parameters improved in both groups. In the TENS group, statistically significant improvements were observed in daytime voiding frequency, 24-hour voiding frequency, and urgency episodes. In the PTNS group, statistically significant improvements were observed in nocturia and urgency urinary incontinence episodes (Table 2).
Interpretation of results
To our knowledge, this is the first double-blind clinical trial in this setting, with both patients and evaluators blinded to treatment allocation (only nurses knew treatment administered), providing a high level of evidence.
This study demonstrates that both transcutaneous and percutaneous tibial nerve stimulation are effective treatments for refractory OAB, with no statistically significant difference between the two approaches. Notably, both techniques reduce urgency or urgency urinary incontinence, one of the most bothersome symptoms.