Overweight and obesity as major, modifiable risk factors for urinary incontinence in young to mid-aged women: a systematic review and meta-analysis : Obesity and urinary incontinence in women

The anatomic structures in the female that prevent incontinence and genital organ prolapse on increases in abdominal pressure during daily activities include sphincteric and supportive systems. In the urethra, the action of the vesical neck and urethral sphincteric mechanisms maintains urethral closure pressure above bladder pressure. Decreases in the number of striated muscle fibers of the sphincter occur with age and parity. A supportive hammock under the urethra and vesical neck provides a firm backstop against which the urethra is compressed during increases in abdominal pressure to maintain urethral closure pressures above the rapidly increasing bladder pressure. This supporting layer consists of the anterior vaginal wall and the connective tissue that attaches it to the pelvic bones through the pubovaginal portion of the levator ani muscle, and the uterosacral and cardinal ligaments comprising the tendinous arch of the pelvic fascia. At rest the levator ani maintains closure of the urogenital hiatus. They are additionally recruited to maintain hiatal closure in the face of inertial loads related to visceral accelerations as well as abdominal pressurization in daily activities involving recruitment of the abdominal wall musculature and diaphragm. Vaginal birth is associated with an increased risk of levator ani defects, as well as genital organ prolapse and urinary incontinence. Computer models indicate that vaginal birth places the levator ani under tissue stretch ratios of up to 3.3 and the pudendal nerve under strains of up to 33%, respectively. Research is needed to better identify the pathomechanics of these conditions.

We reviewed the epidemiological literature on the association of obesity and urinary incontinence, and summarized clinical trial data on the effect of weight loss on urinary incontinence. We systematically searched for published community based prevalence studies with bivariate or multivariate analysis of the association of urinary incontinence and overweight/obesity in women. Case series and randomized controlled trials of the effect of surgical, behavioral and pharmacological weight loss on urinary incontinence are summarized. Epidemiological studies showed that obesity is a strong independent risk factor for prevalent and incident urinary incontinence. There was a clear dose-response effect of weight on urinary incontinence with each 5-unit increase in body mass index associated with about a 20% to 70% increase in the urinary incontinence risk, and the maximum effect of weight rarely exceeded an OR of greater than 4 to 5 on well controlled analyses. The odds of incident urinary incontinence during 5 to 10 years increased by approximately 30% to 60% for each 5-unit increase in body mass index. There may be a stronger association of increasing weight with prevalent and incident stress incontinence, including mixed incontinence, than with urge incontinence and overactive bladder syndrome. Weight loss studies indicated that surgical and nonsurgical weight loss led to significant improvements in urinary incontinence symptoms. Epidemiological studies document overweight and obesity as important risk factors for urinary incontinence. Weight loss by surgical and more conservative approaches is effective to decrease urinary incontinence symptoms and should be strongly considered a first line treatment in this patient population.