Hypothesis / aims of study
Mixed urinary incontinence (MUI) is a complicated disorder of bladder and urethra exhibiting features of both stress urinary incontinence (SUI) and urge urinary incontinence (UUI). Patients with MUI commonly experience more severe symptoms and have significant lower quality of life, compared to pure SUI and UUI (1). The management of MUI remains a challenge since both pharmacotherapy and surgery have relatively high rate of treatment failure (2). Acupuncture has been used to manage various urological diseases over the past decades. In current study, we aim to assess the effect of acupuncture on MUI.
Study design, materials and methods
This study was a randomized, single-blind, placebo-controlled trial. Eligible participants were female, 18 to 75 years of age with MUI for more than 1 year; with more than one incontinence episode per 24 hours. Exclusion criteria were those with other type of urinary incontinence; with acute urinary tract infection, bladder outlet obstruction, interstitial cystitis, or neurogenic bladder; with pelvic organ prolapse > stage 2; with previous anti-incontinence surgery or a post-void residual urine volume >100ml. Participants were randomly allocated into the acupuncture or control group, using a random number generator. Participants in acupuncture group received acupuncture at bilateral BL33, BL35, SP6 and ST36. After the needles were inserted into these points, a portable electro-acupuncture machine was connected to the handles at bilateral BL33 and BL35 to provide the electrical stimulation for 30 minutes with low-frequency (20Hz) disperse-dense wave stimulation. Participants in control group received placebo acupuncture at the sham points which were 2cm lateral to the BL33, BL35, SP6 and ST36 with superficial penetration. A sham electrical stimulation was also used. Participants received 3 treatment sessions per week for 8 consecutive weeks, 24 sessions in total. The primary outcome was cure rate defined as eliminated symptoms based on bladder diary or urine leakage < 2g on the 24h pad test. The secondary outcomes included response rate, change in 24h pad test, incontinence episode, ICIQ-SF and I-QOL questionnaire. Continuous variables were expressed as means ± standard deviation or median (interquartile range) while categorical variables were expressed as percentage and frequency. Difference between two groups was compared by two sample t-test, Mann-Whitney U test or Chi-square test. All reported P-values were two-sided, and P<0.05 was considered statistically significant.
Results
The participants’ demographic are shown in Table 1. After 8-week treatment, acupuncture group presented a significant higher cure rate (16.1% vs 0%, P<0.01) compared to control group, so did response rate (77.4% vs 22.5%, P<0.01). Furthermore, after 8-weeks treatment, participants in acupuncture group experienced a significant improvement in urine leakage, incontinence episodes, the score in ICIQ-SF and I-QOL, but the ones in control did not. In Addition, acupuncture presents a significant benefit compared to placebo intervention.
Interpretation of results
In our study, acupuncture showed a positive effect in treating MUI. The potential mechanism might be as below. Needling at BL33 not only acts on parasympathetic excitatory fibers, but also regulates the sphincter somatic guarding reflex by stimulating the S3 nerve, which may contribute to the participants' symptoms relief. Stimulating pudendal nerve afferents via needling at BL35 may enhance activity of the external urethral sphincter, which may play a part in the improvement of SUI component. On the other hand, needling at SP6 can indirectly excite the pelvic nerves suppressing the detrusor overactivity, which may lead to the improvement of UUI component.