Study design, materials and methods
This is a retrospective cohort study evaluating all surgeons performing synthetic mesh midurethral sling procedures for stress urinary incontinence at a large managed care organization with over 4.5 million members from 2005 to 2016. Physicians’ CPT and ICD-9/10 codes were used to identify the procedures and reoperations performed. The system-wide medical record was queried for demographic and perioperative data. The primary outcome was the overall reoperation rate after midurethral sling. Concentration curves were used to identify the impact of a surgeon’s surgical volume on their rate of reoperation. Demographics, characteristics, and reoperation of patients were compared using chi-square for categorical variables and Wilcoxon rank sum for continuous variables. Poisson regression models with a robust error variance were used to calculate the unadjusted and the adjusted risk ratios of reoperation using age, body mass index, marital status, race, parity, vaginal estrogen use, sling type, smoking, diabetes, and menopausal status as covariates.
227 surgeons performed 13,404 midurethral slings over the study period and patients had a mean of 4.4 years of follow up. Higher-volume surgeons (>40 procedures/year, ≥95th percentile) performed 47% of surgeries in this cohort and had overall lower rate of reoperation (3.6% vs. 4.2%,p=0.04) compared to lower-volume surgeons. Higher-volume surgeons had a lower rate of reoperation for surgical failure (2.7% vs. 3.6%,p<0.01). Rates of reoperation for complications were similar between the two groups (1.1% vs. 0.9%,p=0.32). For patient’s requiring a reoperation secondary to complication, rates of reoperation for urinary retention (0.9% vs. 0.6%,p=0.06), mesh exposure (0.2% vs. 0.3%,p=0.31), hemorrhage/bleeding (0.1% vs. 0.0%,p=0.11), pain (0.1% vs. 0.1%,p=0.52), and infection (0.0% vs. 0.0%,p=0.37) did not differ between higher and lower-volume surgeons. The risk ratio for reoperation comparing higher and lower-volume surgeons was 0.83 (p=0.01) in the adjusted model.
Interpretation of results
In this era of mesh litigation, safety warnings, and product withdrawals we found that among women with SUI who had surgery with a synthetic MUS implant, reoperation rates were low. However, we did find that even after adjusting for potential confounders, patients operated on by higher-volume surgeons (>40MUS/year) had a 17% lower rate of reoperation. While rates of mesh removal/revision were similar between groups, rates of reoperation for SUI was 25% less likely in patients operated on by higher-volume surgeons. While mesh related complications were overall rare, patients operated on by higher-volume surgeons were over 42% less likely to receive another synthetic MUS, further decreasing their mesh burden and thus their risk for future mesh complications. Despite small absolute risk reductions, our results do support the performance of MUS by a higher-volume surgeon. Advanced training through fellowship may be one avenue to obtain the experience needed to perform MUS and is supported by vaginal mesh regulatory notifications and expert opinion. After this training is obtained, performing a higher-volume of MUS may be needed to continue to perform the procedure with low complication and recurrent SUI rates. Furthermore, medical centers could consider having potential surgeons demonstrate a level of experience, training or volume prior to credentialing them to perform MUS.