Success rates were much lower than previously reported
These findings are particularly striking because the success rates are lower than in previous reports—and lower than the figures commonly used by surgeons to counsel women about likely results. “Success” for either procedure has been commonly quoted in the 80% to 90% range, not the 30% to 40% range found here. The authors are to be commended for the stringent definition of “success,” which included elements that invariably result in a lower success rate. It is these numbers that women are most interested in when they are considering this type of surgery.
The difference between sling and Burch procedures was particularly remarkable in regard to stress success (17 percentage points). The smaller difference seen for overall success (9 percentage points) can be attributed to the increase in postoperative urge incontinence among women undergoing the sling procedure.
If the other adverse events associated with the sling procedure (i.e., urinary tract infection and voiding difficulty) had been included in the composite measure of success, it seems possible, if not likely, that a smaller difference—or no difference at all—would have been seen between the sling and Burch groups.
Additional data still to come
Follow-up of women in this trial has been extended for up to 5 years and should provide much-needed information on longer-term results after these surgeries.
Transobturator mid-urethral sling linked to fewer complications
Sung VW, Schleinitz MD, Rardin CR, Ward RM, Myers DL. Comparison of retropubic versus transobturator approach to mid-urethral slings: a systematic review and meta-analysis. Am J Obstet Gynecol. 2007;197:3–11.
In this Update 1 year ago, I remarked on the need for more comparative information about the various mid-urethral slings currently on the market, particularly in regard to complications—information necessary to make recommendations and guide clinical decision-making.
Originally, the procedure for mid-urethral sling placement was modified from the retropubic approach to the obturator approach with the aim of reducing the risk of major bladder and urethral injury and vascular complications (FIGURE 1). Recent data suggest that that goal has been achieved. In a systematic review and meta-analysis of 17 studies that compared retropubic and transobturator approaches, Sung and colleagues found the transobturator route to be associated with fewer complications.
FIGURE 1 Transobturator approach lives up to promise
The retropubic approach (A) was modified to create the transobturator approach (B), with the aim of protecting the bladder, urethra, and vascular structures. A recent meta-analysis indicates that this goal was achieved.
Subjective and objective outcomes were similar for the two approaches
Overall, 492 women in six trials were randomly assigned to receive either a retropubic or transobturator mid-urethral sling for treatment of stress incontinence. Although some trials specified exactly which device was used, others did not. Follow-up ranged from 1 to 15 months.
Because the studies used different definitions of objective success as outcomes, it was not possible to obtain a pooled estimate for objective outcomes. However, the authors were able to calculate a pooled estimate for subjective outcomes by defining subjective success as a woman reporting either continence or improved status after surgery, and by defining failure as a woman reporting unchanged or deteriorating incontinence status.
The pooled odds ratio for subjective failure after transobturator placement of a mid-urethral sling was 0.85, compared with the retropubic approach (95% CI, 0.38–1.92). Results were relatively stable despite changes in definitions of success and failure and restriction to studies with more than 1 year of follow-up. Sung and colleagues concluded that evidence was insufficient to support one or the other approach in regard to subjective or objective outcomes.
Bladder perforation was most common complication
Findings regarding complications were more conclusive. Again drawing on data from six randomized trials, the authors estimated a pooled odds ratio for complications from transobturator placement of 0.40, compared with the retropubic approach (95% CI, 0.19–0.83). Using data from both randomized trials and cohort studies, the most common complications were:
- bladder perforation: 3.5% for retropubic placement, 0.2% for the transobturator route
- hematoma: 1.5% for retropubic placement, 0.08% for the transobturator route.
More definitive data are in the works
As noted here last year, the Urinary Incontinence Treatment Network is enrolling women with stress or stress-predominant mixed incontinence in a randomized trial to compare the retropubic and transobturator approaches for mid-urethral slings. With a sample size of 655 women and 2-year follow-up planned, this trial should be adequately powered to detect clinically important differences, if they exist, in both continence outcomes and complications. Enrollment is projected to close in 2008, with results to follow 2 years later.