Urologic Diseases Research Updates
Study Finds Two Sling Surgeries Equally Effective for Bladder Control in Women
Two common operations for stress urinary incontinence (SUI) help women achieve similar levels of dryness, according to a team of urologists and urogynecologists who com-pared the treatments in a large U.S. trial supported by the National Institutes of Health (NIH). The study was published in the June issue of The New England Journal of Medicine to coincide with a presentation at the annual meeting of the American College of Obstetrics and Gynecology.
The Trial of Mid-Urethral Slings (TOMUS) 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 made of 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 self-reported dryness, 56 percent of women in the transobturator group and 62 percent of women in the retropubic 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., M.A.C.P., 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 when 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 U.S. Food and Drug Administration and have been performed in the United States for more than a decade.
The study randomized 597 women with SUI to receive either a transobturator or retropubic 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 has different risks and side effects. Serious adverse events were more common in the retropubic group (14 percent), compared with the transobturator group (6 percent). The retropubic group experienced more bladder perforations during surgery and serious voiding, or bladder emptying, problems requiring surgical correction, while the transobturator group experienced more vaginal perforations during surgery and neurological problems, such as weakness of the upper leg. Blood loss during surgery, duration of surgery, and likelihood of post-surgery urinary tract infections were all modestly higher in the retropubic group, compared with the transobturator group.
The study defined two types of treatment success. The surgery was deemed an objective success if participants had no leakage during a stress test and a 24-hour pad test, and they required no additional treatment for the problem. Women also reported leakage using validated questionnaires and a 3-day voiding diary and reported additional treatment, such as surgery, behavioral therapy, or drug therapy. Negative results on all of these measures meant the surgery was a subjective success.
Overall, subjective self-reported treatment success was lower than objective success, a common finding among 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.
The NIDDK, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the 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 the NIDDK. “The study also highlights potential complications that doctors and patients need to discuss before surgery.”
Many urinary incontinence studies predating the UITN study were small, short-term, or less stringent about diagnostic criteria and outcome measures, producing inconsistent results across studies. The UITN study 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 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 women. Another study funded by the NIH reports that approximately half of American 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.
The TOMUS 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 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. More information is available at www.springerlink.com/content/tj7272157274k833 .
More information about research projects funded by the NIH can be found by using the Research Portfolio Online Reporting Tools (RePORT) Expenditures and Results (RePORTER) tool located at www.projectreporter.nih.gov/reporter.cfm. The research described in this article is funded under NIDDK grant number 5U01DK060395–08. The direct link to the project is www.projectreporter.nih.gov/project_info_description.cfm?aid=7686867&icde=3850292.
For a list of centers enrolling patients for urinary incontinence trials, visit www.uitn.net or search for urinary incontinence at www.ClinicalTrials.gov, where the TOMUS study is registered as NCT00325039.
For materials from the NIDDK about bladder control for women, visit www.kidney.niddk.nih.gov/kudiseases/pubs/bladdercontrol.
NIH Publication No. 10-5743