Two common operations for stress urinary incontinence (SUI) help women achieve similar levels of dryness, according to a team of urologists and urogynecologists who compared the treatments in a large U.S. trial supported by the National Institutes of Health. The study is being released online May 17, 2010, by the New England Journal of Medicine to coincide with a presentation at the annual meeting of the American College of Obstetrics and Gynecology. Results will appear in the June 3 print edition.

The Trial of Mid-Urethral Slings found that the two most common mid-urethral sling procedures are similar in their chance of cure, though each surgery has different risks. Mid-urethral slings are a synthetic mesh material that acts as a hammock, or sling, to support the urethra and prevent leakage. The urethra is the tube through which urine passes out of the body.

One of the mid-urethral sling procedures tested by this study is transobturator, meaning through the obturator area of the pelvis. It passes the sling material under the urethra and out through the upper inner thigh or groin area. The other procedure is retropubic, or behind the pubic bones of the pelvis. It passes a sling material under the urethra and behind the pubic bone.

Twelve months after surgery, women who received the transobturator mid-urethral sling and women who received the retropubic mid-urethral sling had equivalent levels of treatment success: 78 to 81 percent of women achieved dryness. Considering only women’s self-reported dryness, 62 percent in the retropubic group and 56 percent in the transobturator group reported they had been cured, a small difference between the two groups that could have occurred by chance.

“This rigorous, large-scale, comparative effectiveness trial represents a major milestone in treatment for stress urinary incontinence, an underdiagnosed public health problem affecting millions of American women,” said Griffin P. Rodgers, M.D., director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the NIH. “Investments in this kind of research enable women and their doctors to weigh more accurately the benefits and risks of available treatment options.”

Women with SUI leak urine with coughing, laughing, sneezing, running or lifting heavy objects. SUI is commonly treated with surgery designed to provide additional support to the bladder neck and urethra during increases in abdominal pressure that occur with activities. Mid-urethral sling surgeries are approved by the FDA and have been performed in the United States for more than a decade.

The study randomized 597 women with SUI to receive either a retropubic or transobturator mid-urethral sling. Complete information used to assess urinary incontinence was available for 95 percent of patients 12 months after surgery. Quality of life, patient satisfaction and side effects were also studied. Most women in the study were satisfied with the results of treatment.

Each type of surgery had different risks and side effects. Serious adverse events were more common in the retropubic group (14 percent), compared to the transobturator group (6 percent). More bladder perforations during surgery and serious voiding, or bladder emptying, problems requiring surgical correction occurred in the retropubic group, while more vaginal perforations during surgery and neurological problems like weakness of the upper leg occurred in the transobturator group. Blood loss during surgery, duration of surgery, and likelihood of post-surgery urinary tract infections were all modestly higher in the retropubic group, compared to the transobturator group.

The study defined two types of treatment success. The surgery was deemed an objective success if participants had a no leakage during a stress test and a 24-hour pad test, and they had no additional treatment for the problem. Women also reported leakage using validated questionnaires and a three-day voiding diary, and reported additional treatment with surgery, behavioral therapy, or drug therapy. A negative result on all of these measures meant that the surgery was a subjective success.

Overall, subjective self-reported treatment success was lower than objective success, a finding common to many scientific studies of urinary incontinence. Cure rates in this clinical trial were lower than in previous studies, likely because participants had to test negative on several measures, rather than just one. Similar to previous studies of urinary incontinence, researchers found that women with more severe urethral dysfunction were no more likely to fail with the transobturator sling than with the retropubic sling.

NIH’s NIDDK, National Institute of Child Health and Human Development and Office of Research on Women’s Health fund the Urinary Incontinence Treatment Network (UITN), a group of nine clinical centers and a biostatistical center. The UITN conducts rigorous, long-term clinical trials of common therapies for incontinence. The Office of Research on Women’s Health also provides support for extended follow-up of the women enrolled in the study to observe the long-term effects of these surgeries.

“Patient-reported treatment success combined with clinical measures of success gives us clear evidence about the comparative effectiveness of these two procedures and the risks associated with each approach,” said Robert A. Star, M.D., director of the Division of Kidney, Urologic, and Hematologic Diseases at NIDDK. “The study also highlights potential complications that doctors and patients need to discuss before surgery.”

Many urinary incontinence studies predating the UITN were small, short-term or less stringent about diagnostic criteria and outcome measures, producing inconsistent results across studies. The UITN set a higher bar by standardizing definitions, clinical evaluations, and surgical procedures at all sites and by using many measures of treatment success, which may increase the applicability of study results to other patients who did not participate in the study. Prior to this study, few clinical trials had been conducted to compare these operations for both likelihood of treatment success and risks.

Urinary incontinence is a common and costly condition that results in poorer quality of life for American women. Another study funded by the NIH reports that approximately half of women have some degree of urinary incontinence, and the direct cost of incontinence for women was $12.4 billion in 1995, the last year for which national estimates are available.

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The Trial of Mid-Urethral Slings is the third in a series of clinical trials completed by the UITN. The first, the Stress Incontinence Surgical Treatment Efficacy Trial, compared two older, gold standard surgeries for SUI. More about those results is available at http://www.nih.gov/news/pr/may2007/niddk-21.htm. The second trial, the Behavior Enhances Drug Reduction of Incontinence, asked women to make behavioral changes such as emptying the bladder on a regular schedule and practicing pelvic muscle exercises, known as Kegel exercises, to strengthen pelvic muscles to determine if these common treatments would allow women to stop drug therapy and maintain the same degree of bladder control.

For a list of centers enrolling patients for urinary incontinence trials, visit http://www.uitn.net or search for urinary incontinence at http://www.clinicaltrials.gov, where the TOMUS study is registered as NCT00325039.

For materials from the NIDDK about bladder control for women, visit http://www.kidney.niddk.nih.gov/kudiseases/pubs/bladdercontrol/index.htm.

The NIDDK, part of the NIH, conducts and supports basic and clinical research and research training on some of the most common, severe and disabling conditions affecting Americans. The Institute’s research interests include diabetes and other endocrine and metabolic diseases; digestive diseases, nutrition and obesity; and kidney, urologic and hematologic diseases.

The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation.

The NIH’s Office of Research on Women’s Health serves as the focal point for women’s health research at the NIH. For more information about NIH’s Office of Research on Women’s Health.

The National Institutes of Health (NIH) — The Nation’s Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical, and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases.
To interview lead author Dr. Holly E. Richter, at the University of Alabama at Birmingham, contact Donna B. Campbell at 205-934-1704 or .(JavaScript must be enabled to view this email address).

Contact: Britt Ehrhardt
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NIH/National Institute of Diabetes and Digestive and Kidney Diseases