Online Model May Predict Incontinence After Vaginal Surgery

Larry Hand

January 23, 2014

A personalized prediction model for stress urinary incontinence (SUI) after pelvic organ prolapse (POP) surgery may be more accurate than preoperative stress testing and prediction by experts, according to an article published online January 7 in Obstetrics & Gynecology.

J. Eric Jelovsek, MD, from the Obstetrics, Gynecology & Women's Health Institute and Quantitative Health Sciences, Cleveland Clinic, Ohio, and colleagues wrote the article on behalf of the Pelvic Floor Disorders Network.

The researchers constructed a model of 12 clinical preoperative predictors of de novo SUI, using data from the Outcomes Following Vaginal Prolapse Repair and Midurethral Sling Trial (OPUS). The variables included age at surgery, white race, higher vaginal parity, and higher body mass index.

"Because patients frequently ask clinicians to estimate their risk of leaking after surgery for POP, the model was compared with the best currently available method of estimating risk, a clinician's predictions," the researchers write. "The performance of the model was also compared with results from the preoperative prolapsed reduction stress test, also commonly used by clinicians to counsel patients on their postoperative risk of de novo SUI."

The researchers used multivariate logistic regression analysis, adjusting for the 12 variables to measure de novo SUI through 12 months postoperatively, as determined by Pelvic Floor Distress Inventory They used a stepdown method of elimination to narrow the variables down to 7 for a final nomogram: age at surgery, number of vaginal births, body mass index, preoperative stress test, continence procedure, urine leakage associated with a feeling of urgency, and diagnosis of diabetes.

The researchers studied a subset of 32 patients who were randomly selected from the trial data set. They asked 22 expert surgeons to review the subset and then compared the model's predictions with experts' predictions and preoperative stress tests.

Of 465 women who underwent POP surgery in the OPUS trial, 457 (98%) had SUI data available 12 months afterward. Of the women who underwent a retropubic midurethral sling procedure, 21% had de novo SUI compared with 79% of the women who did not undergo that procedure (P < .001).

The 7-variable model discriminated between de novo status in the study (concordance index, 0.73; 95% confidence interval, 0.65 - 0.80) and outperformed expert clinicians (P < .001) and preoperative urinary stress testing (P < .001).

One Surprise

Although the researchers hypothesized that all 7 risk factors in their model would predict incontinence in this population, in the end, 1 of them did not. "We predicted that increasing age would increase the risk of developing de novo SUI. Contrary to that assumption, the results demonstrated that as age increased, a participant's risk of experiencing de novo SUI after POP surgery decreased," they write.

The researchers validated their final model by comparing their findings with outcomes from the Colpopexy and Urinary Reduction Efforts (CARE) trial.

The final model had a tendency to overpredict when the probability of SUI approached 50%, the researchers write, but the overestimation "is likely of little clinical consequence because most clinicians will likely offer a prophylactic continence procedure with risks of de novo SUI greater than 50%."

They conclude, "[I]n women undergoing transvaginal POP surgery, this model provides a valid individualized risk estimate for the development of de novo SUI symptoms that performs better than an estimate from subspecialty experts and a preoperative stress test. The findings and model's ease of use also suggest that the model would be appropriate for physicians to use in clinical settings when discussing possible surgery for POP with their patients."

In the Clinic

The researchers created an online calculator that uses the final 7 variables as a model for making clinical predictions in clinical settings.

The question of whether to perform a SUI procedure at the same time as vaginal surgery "is extremely difficult to answer and typically has been based on some expert opinion, surgeons' experience, and inconsistent preoperative physical examination testing," Jeffrey B. Garris, MD, a urogynecologist with the Greenville Health System in South Carolina, who was not involved in the study, told Medscape Medical News.

"If you ask me would it be of value to have a measuring device or a predicting device, I think this could be one of the most beneficial things that we've seen in the field of pelvic reconstructive surgery in quite some time. It would be an enormous benefit to have a user-friendly, accurate assessment tool," Dr. Garris said. "The practicality is, if I could have a nomogram where I could easily insert data from my patient and predict the outcome with confidence, that would certainly give me things of benefit in a preoperative discussion with a patient."

Citing the model's tendency to overpredict and the fact that it applies only to transvaginal surgery, he added, "I think the nomogram is a great assessment tool, but it also has limitations. This initial publication will open it up to further evaluation and testing and challenges to see if this actually works."

"Because every woman undergoing prolapse surgery is at risk for postoperative incontinence, having any additional tool that can provide information preoperatively can be informative to the counseling, but like anything, it's not perfect," Catherine A. Matthews, MD, associate professor and division chief, Urogynecology and Reconstructive Pelvic Surgery, University of North Carolina, Chapel Hill, told Medscape Medical News.

She said the need for prolapsed or incontinence surgery is "extremely prevalent" and that 1 of 5 women will undergo such a procedure in their lifetime. She cautioned, "I think it is important for people to remember that it is just a model, and using common sense and making sure that you really understand your individual patient is more important than what the model says."

This research was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Institutes of Health Office on Women's Health. One coauthor has reported receiving royalties from UpToDate and from the American College of Obstetrics and Gynecology and has been the Data Safety Monitoring Chair for the TRANSFORM trial, sponsored by American Medical Systems, and 1 coauthor has reported receiving research grants from 3 companies and serving as a consultant to 2 of them. The other authors, Dr. Garris, and Dr. Matthews have disclosed no relevant financial relationships.

Obstet Gynecol. 2014;123:279-287. Abstract

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