Hypothesis / aims of study
Overactive bladder (OAB) syndrome substantially impairs quality of life, social participation and daily functioning for affected women. Conventional managements such as oral therapies result in systemic adverse effects, cost and
long‑term tolerability issues. Parasacral transcutaneous electrical nerve stimulation (TENS) may improve OAB symptoms
without systemic toxicity and could represent an attractive alternative or adjunctive therapy. We aimed
to compare the efficacy and safety of parasacral TENS versus sham stimulation and mirabegron in
women with OAB undergoing concomitant pelvic floor muscle training (PFMT), focusing on symptom
severity, incontinence impact and health‑related quality of life over a 4‑month follow‑up period.
Study design, materials and methods
This single‑blind, parallel‑group randomized controlled trial enrolled women aged 18 to 75 years with
OAB symptoms for at least 3 months, defined by urinary urgency with increased daytime frequency,
nocturia and/or urgency urinary incontinence according to standardized symptom diary criteria.
Participants were randomized in a 1:1:1 ratio to one of three groups: parasacral TENS (24 sessions over 8
weeks at 10 Hz, pulse width 500 to 700 microseconds, intensity adjusted to the maximal tolerable level),
sham TENS (identical procedures without current delivery) or oral mirabegron 50 mg once daily. All
groups received supervised progressive PFMT for 6 to 8 weeks, consisting of daily home exercises
reinforced during clinic visits. Outcome assessors were blinded to allocation and had no role in
treatment delivery. Primary outcomes were changes in lower urinary tract symptom severity and related
outcomes at baseline, 2 months and 4 months, measured using the ICIQ‑OAB, ICIQ‑UI SF and LUTS‑QoL questionnaires. Secondary outcomes were treatment‑emergent adverse events.
Analyses followed an intention‑to‑treat approach with significance set at 0.05.
Results
Eighty‑two women were randomized (TENS n=22, sham n=25, mirabegron n=35). Baseline age and
questionnaire scores were comparable between groups, and baseline ICIQ‑OAB scores indicated severe
OAB across all arms (approximately 13.4 to 13.9). At 2 months, mirabegron produced greater ICIQ‑OAB
improvement than TENS (mean reduction 4.06 ± 1.15 versus 1.45 ± 0.72, p<0.05). At 4 months, ICIQ‑OAB
reductions remained significantly different: TENS −3.50 ± 0.91 (final 10.36 ± 0.79) versus sham −1.36 ±
0.76 (final 12.08 ± 0.81, p<0.05; Cohen’s d=1.456) and mirabegron −4.69 ± 1.53 (final 9.14 ± 1.38) versus
sham (p<0.01; d=2.218), with mirabegron superior to TENS (p<0.05; d=1.362). At 4 months, ICIQ‑UI SF
scores improved more with mirabegron (final 7.31 ± 0.63; 45% reduction from baseline) than with TENS
(10.95 ± 0.90; 16% reduction) or sham (11.04 ± 0.54; 16% reduction; mirabegron versus both p<0.05),
while TENS did not differ from sham. LUTS‑QoL improved similarly in the TENS and mirabegron groups at
4 months (final 26.86 ± 1.36 versus 27.77 ± 1.86; between‑group p>0.05), and both were superior to
sham (p<0.05). Adverse events with TENS and sham were limited to mild skin irritation in 9 of 47
participants, whereas mirabegron‑related events included dry mouth (n=7), headache (n=5) and
palpitations (n=4).
Interpretation of results
In women with moderate‑to‑severe OAB receiving PFMT, mirabegron provided a faster and larger
reduction in symptom severity and urinary incontinence episodes than parasacral TENS or sham,
reflected in greater early improvements in ICIQ‑OAB and ICIQ‑UI SF scores. Parasacral TENS, however,
produced progressive symptom improvement over time and yielded quality‑of‑life gains that were
comparable to mirabegron at 4 months, while clearly outperforming sham stimulation. The
neuromodulatory effect of parasacral TENS, delivered in a standardized protocol alongside PFMT, likely
contributes to these sustained benefits, with a favourable local tolerability profile and minimal systemic
adverse effects.