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Surgeon volume and reoperation risk after midurethral sling surgery
Journal Pre-proof Surgeon Volume and Reoperation Risk after Midurethral Sling Alexander A. Berger, MD MPH, Jasmine Tan-Kim, MD, Shawn A. Menefee, MD PII:
S0002-9378(19)31111-1
DOI:
https://doi.org/10.1016/j.ajog.2019.09.006
Reference:
YMOB 12877
To appear in:
American Journal of Obstetrics and Gynecology
Received Date: 31 December 2018 Revised Date:
4 September 2019
Accepted Date: 10 September 2019
Please cite this article as: Berger AA, Tan-Kim J, Menefee SA, Surgeon Volume and Reoperation Risk after Midurethral Sling, American Journal of Obstetrics and Gynecology (2019), doi: https:// doi.org/10.1016/j.ajog.2019.09.006. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
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Surgeon Volume and Reoperation Risk after Midurethral Sling Alexander A. Berger MD MPH,1,2 Jasmine Tan-Kim MD,1 Shawn A. Menefee MD1
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Word Count: Abstract-420, Manuscript-2738
1
Division of Female Pelvic Medicine and Reconstructive Surgery, Department of OB/GYN, Kaiser Permanente-San Diego 2
Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics, Gynecology and Reproductive Science, University of California San Diego
Corresponding Author: Alexander A. Berger MD MPH 3250 Fordham Street, Bldg A, Ob/Gyn Department, San Diego, CA 92110 Phone: 858-534-8930 Email: [email protected] Email: [email protected] Conflicts of interest: A.A.B.: None, J.T.K.: None, S.A.M.: None. The research is supported by a grant from the Regional Research Committee of Kaiser Permanente Southern California, Grant No. KP-RRC-20171101. The granting organization had no role in the study design, data collection, analysis and interpretation of data, writing of manuscript or decision to submit the article for publication. This work was accepted as an oral presentation at the 45th Annual Meeting of the Society of Gynecologic Surgeons (Tuscon AR, March 2019).
Condensation: Higher volume surgeons have lower reoperation rates after midurethral sling surgery. Short Title: Surgeon volume and reoperation after midurethral sling.
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AJOG at a Glance
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A. Why was this study conducted?
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To measure the impact of a surgeon’s procedural volume on their patient’s rate of reoperation
45
after midurethral sling surgery.
46
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B. What are the key findings?
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While reoperation rates were low for both higher and lower-volume surgeons, higher-volume
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surgeons have lower overall rates of reoperation after midurethral sling. This effect is seen most
50
dramatically in reoperation for surgical failure, where patients who have surgery with a higher-
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volume surgeon are 25% less likely to have post-operative stress urinary incontinence leading to
52
reoperation.
53 54
C. What does this study add to what is already known?
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Mesh litigation and warnings are increasingly impacting the availability of and comfort with
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midurethral slings for stress urinary incontinence. This paper adds to the growing literature on
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safety and efficacy of midurethral slings and shows that higher volume surgeons consistently
58
have lower reoperation rates. This supports the continued use of midurethral slings and efforts to
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promote highly trained, experienced surgeon’s performing the procedures.
60 61 62
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Structured Abstract
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Background: Emerging research supports that fewer complications occur in patients operated on
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by higher surgical volume surgeons. The midurethral sling has been involved in recent warnings
66
and litigation, further supporting a need to understand features that enhance its safety and
67
efficacy.
68
Objective: To measure the impact of a surgeon’s volume on their patient’s rate of reoperation
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after midurethral sling surgery.
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Study Design: This is a retrospective cohort study evaluating all surgeons performing synthetic
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mesh midurethral sling procedures for stress urinary incontinence at a large managed care
72
organization with over 4.5 million members from 2005 to 2016. Physicians’ CPT and ICD-9/10
73
codes were used to identify the procedures and reoperations performed. The system-wide
74
medical record was queried for demographic and perioperative data. The primary outcome was
75
the overall reoperation rate after midurethral sling. Concentration curves (figure 2) were used to
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identify the impact of a surgeon’s surgical volume on their rate of reoperation. Demographics,
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characteristics, and reoperation of patients were compared using chi-square for categorical
78
variables and Wilcoxon rank sum for continuous variables. Poisson regression models with a
79
robust error variance were used to calculate the unadjusted and the adjusted risk ratios of
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reoperation using age, body mass index, marital status, race, parity, vaginal estrogen use, sling
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type, smoking, diabetes, and menopausal status as covariates.
82
Results: 227 surgeons performed 13,404 midurethral slings over the study period and patients
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had a mean of 4.4 years of follow up. Higher-volume surgeons (>40 procedures/year, ≥95th
84
percentile) performed 47% of surgeries in this cohort and had overall lower rate of reoperation
85
(3.6% vs. 4.2%,95% CI 0.67, 0.94 (p=0.04)) compared to lower-volume surgeons. Higher-
86
volume surgeons had a lower rate of reoperation for surgical failure (2.7% vs. 3.6%, 95% CI
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0.55-0.92 (p<0.01)). Rates of reoperation for complications were similar between the two groups
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(1.1% vs. 0.9%,95% CI 0.82-1.13(p=0.32)). For patients requiring a reoperation secondary to
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complication, rates of reoperation for urinary retention (0.9% vs. 0.6%,p=0.06), mesh exposure
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(0.2% vs. 0.3%,p=0.31), hemorrhage/bleeding (0.1% vs. 0.0%,p=0.11), pain (0.1% vs.
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0.1%,p=0.52), and infection (0.0% vs. 0.0%,p=0.37) did not differ between higher and lower-
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volume surgeons. The risk ratio for reoperation comparing higher and lower-volume surgeons
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was 0.83 (95% CI 0.67,0.98 (p=0.01)) in the adjusted model.
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Conclusions: While reoperation rates were low for both higher and lower-volume surgeons,
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higher-volume surgeons have lower overall rates of reoperation after midurethral sling. This
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effect is seen most dramatically in reoperation for surgical failure, where patients who have
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surgery with a higher-volume surgeon are 25% less likely to have post-operative stress urinary
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incontinence leading to reoperation.
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Key Words: Midurethral slings, surgeon volume, reoperation, safety, efficacy.
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Introduction
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Midurethral slings (MUS) were developed in the mid-1990s1 and have become the most
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commonly used surgical treatment worldwide for stress urinary incontinence (SUI), a condition
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that affects 1 in 3 adult women throughout their lives.2 Approximately 250,000 MUS surgeries
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are performed annually in the United States.3 The MUS involves the placement of 1 cm wide
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ribbon of polypropylene mesh under the mid-urethra. MUS has the same treatment success rates,
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but less morbidity than suburethral fascial slings and open retropubic colposuspension, two
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traditional procedures. For example, women undergoing MUS have short-term cure rates of 62-
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98% and the advantage of fewer perioperative complications, take less operating room (OR)
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time, have shorter hospital stays, lower rates of venous thromboembolism (VTE), and have lower
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bladder perforations compared to the open retropubic colposuspension.2 Furthermore, success
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after MUS has been shown to be long lasting with a subjective cure rate as high as 87% after 17-
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years of followup.4
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In 2011, the Food and Drug Administration (FDA) published a safety communication
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regarding the use of transvaginal mesh for pelvic organ prolapse (POP). This statement was in
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response to concerns over surgical complications involving the use of mesh in these patients.5
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While the FDA specifically excluded MUS mesh in its 2011 report as well as their 2013 and
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2016 updated classifications, the medicolegal community has grouped the two together in their
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litigation efforts. In the United States more than 50,000 women have joined class action lawsuits
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for transvaginal mesh complications resulting from SUI and prolapse procedures.5 Secondary to
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the public and financial pressures, several companies (Endo International, Astora) that supply
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MUS have stopped producing them.5 While additional long-term data is needed2,5,6 overall
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reoperation after MUS surgery is uncommon. Work from our group and other large retrospective
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studies have found a rate of any reoperation of 4.5-5.5%,7-8 while reoperation for recurrent SUI
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and MUS mesh removal was 3.5-3.9%7-8 and 1.0-3.4%7-9 respectively at 5 years.
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Emerging research is supporting that fewer complications occur in patients operated on
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by high surgical volume surgeons.10-12 A recent systematic review of gynecologic surgeries
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found that a low-volume surgeon (defined in that study as performing a procedure once a month
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or less) had a 1.3 odds ratio of complications compared to those who performed procedures more
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frequently.10 After placement of MUS there was a 37% increase in risk of reoperation for mesh
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removal/revision for low volume surgeons (defined as the bottom three quartiles or <16
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MUS/year) in a Canadian study.11 With additional evidence in MUS, surgeon volume could be
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considered as a component of enhancing the safety and efficacy of MUS.
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144 145 146 147 148 149 150 151 152
Our objective was to study whether women who underwent MUS for SUI by highvolume surgeons have lower incidence of reoperations for adverse events and recurrent SUI.
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Materials and Methods This is a sub-analysis of a retrospective cohort study8 evaluating all surgeons performing
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synthetic mesh MUS for SUI at a large managed care organization (with currently over 4.5
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million members) from 2005 to 2016. The study was approved by the Kaiser Southern California
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IRB (#11508). Patients within the Kaiser system obtain all healthcare, with rare exception,
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within this system and have a high retention rate.13 The system-wide medical record and linked
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surgical database (HealthConnect Clarity) was queried and an algorithm was created to obtain
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patient data regarding primary MUS and reoperation, as well as demographic and perioperative
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data using physicians’ CPT and ICD-9/10 codes. The primary outcome (overall reoperation rate
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after MUS) as well as secondary outcomes (specific reoperation rates for surgical failure and
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complications) were assessed. Types of reoperation for complication assessed with urinary
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retention, mesh exposure, pain, bleeding, infection, nerve injury, retropubic hematoma,
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bladder/urethral injury, and bowel injury. Intraoperative complications were excluded. Types of
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reoperation for surgical failure were assessed and included repeat MUS, bulking injection,
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laparoscopic and open retropubic urethropexy, abdominovaginal vesical neck suspension, Kelly
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plication, cystourethropasty and needle urethropexy. Additionally, the postoperative
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complications of urinary tract infection (UTI) (defined as symptoms and greater than 105 colony
170
forming units on urine culture), recurrent UTI, and urinary retention were assessed.
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With the assistance of the Kaiser Permanente National Implant Registry, surgical implant
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logs containing the product name, product number and manufacturer, as well as additional codes
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were used to identify the MUS implants used. Subjects demographic and clinical data, including
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age, ethnicity, marital status, body mass index (BMI, calculated as weight (kg)/[height (m)]2),
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smoking status, parity, presence or absence of diabetes, post-menopausal status, and estrogen use
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were obtained. MUS implants were classified as retropubic, transobturator, or single incision.
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Medical records and operative reports of patients with multiple implants and reoperations were
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reviewed individually to verify the algorithm correctly identified the implant and instances of
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reoperation. Validation measures were implemented, and the accuracy of data abstraction was
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verified in a sample of subjects as well as those subjects with reoperation and appropriate
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modifications were made to ensure internal validity. Subjects in which data could not be verified
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or were missing were excluded.
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Surgeon MUS volume, the primary exposure of interest was classified with the use of the
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linked databases and unique physician identifiers. With the assistance of the Kaiser Southern
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California Quality and Clinical Analysis group, concentration curves14 were used to identify the
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impact of a surgeon’s surgical volume on their rate of reoperation. Cumulative percentage of
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MUS ranked from lowest to highest on annual surgeon procedure volumes were plotted on the X
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axis while cumulative percentage of reoperations were plotted on the Y-axis. The 45-degree line
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of equality represents reoperations that are dispersed equally across surgeons with a range of
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MUS surgical volumes. Curves above this line indicate reoperations occurring disproportionately
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among lower-volume surgeons. A concentration index (CI) was then used to assess the summary
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measurement of inequality in reoperation rate.
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All analyses were performed using SAS 9.4(SAS Institute Inc., Cary, North Carolina).
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Demographics, characteristics, and reoperation of patients operated by higher and lower-volume
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surgeons were compared using chi-square for categorical variables and Wilcoxon rank sum for
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continuous variables. Poisson regression models with a robust error variance were used to
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calculate the unadjusted and the adjusted risk ratios of reoperation using age, BMI, marital
198
status, race, parity, vaginal estrogen use, sling type, smoking, diabetes, and menopausal status as
199
covariates.
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Results
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Demographics of the cohort
218
From 2005 to 2016 we identified 17,030 women who underwent a primary synthetic
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MUS for SUI within the health system of which 13,404 had identifiable surgeon and could be
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reliably classified into the higher and lower volume groups (Figure 1). The mean follow-up was
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4.4 (SD 2.77) years and did not differ between patients operated on by higher and lower-volume
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surgeons. Demographics are presented in Table 1 and differences between those operated on by
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higher and lower-volume surgeons are noted. Patients operated on by higher-volume surgeons
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were older (mean and SD age 55.6 (11.9) vs. 54.1 (11.7) years old, p<0.01), more likely to be
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white (p<0.01), widowed (p=0.03), more likely to have a single incision sling (16.2% vs. 4.4%,
226
p<0.01), and be post-menopausal (65.0% vs. 59.2%, p<0.01) while also being less likely a
227
smoker (3.8 vs. 5.2%, p<0.01).
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Demographics of the surgeons
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The surgeries were performed by 227 unique surgeons, with a range of 11 to 167
231
surgeons performing MUS in a given year. More surgeons performed MUS over time. Surgeons
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performed 1 to 135 MUS in a given year, with a mean volume of 10, and most performing ≤10
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MUS per year (Figure 3). The concentration curve was examined, and we found that at the ≥95%
234
(>40MUS/year) there was a statistically significant difference in reoperation rate. The higher-
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volume surgeons (>40 MUS/year) performed 47% (7073/13404) of the MUS in the cohort. Most
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higher volume surgeons were fellowship (75%) and gynecology (87%) trained.
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Reoperation Results Patients operated on by higher-volume surgeons had a lower rate of all-cause reoperation
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(3.6% vs. 4.2%, p=0.04) compared to those operated on by lower-volume surgeons (Table 2).
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This is a relative risk of 0.86 and absolute risk reduction of 0.6% reoperation for patients
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operated on by higher-volume surgeons.
242 243
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Reoperation for mesh revision/removal secondary to complication results The rate of MUS mesh sling removal/revision was similar between those patients
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operated on by higher and lower-volume surgeons (1.1% vs. 0.9%,p=0.32). For patients
246
requiring a reoperation to remove or revise their MUS mesh sling, rates of sling removal for
247
urinary retention (0.9% vs. 0.6%,p=0.06), mesh exposure (0.2% vs. 0.3%,p=0.31), pain (0.1%
248
vs. 0.1%,p=0.52), hemorrhage/bleeding (0.1% vs. 0.0%,p=0.11), and infection (0.0% vs.
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0.0%,p=0.37) did not differ between higher and lower-volume surgeons. There were no cases of
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MUS mesh sling removal/revision for nerve injury, retropubic hematoma, bladder, urethral, or
251
bowel injury during the study period.
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253
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Reoperation for surgical failure Patients operated on by higher-volume surgeons for their primary MUS had a lower rate
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of reoperation for SUI (2.7% vs. 3.6%,p<0.01). This is a relative risk of 0.75 and absolute risk
256
reduction of 0.9% reoperation for patients operated on by higher-volume surgeons. When
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compared with patients operated on by lower-volume surgeons, patients operated on by higher-
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volume surgeons had a lower rate of repeat MUS (1.5% vs. 2.5%,p<0.01) and laparoscopic
259
retropubic urethropexy (0.0% vs. 0.3%,p<0.01). Rates of treatment for SUI after primary MUS
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by bulking injections (0.9% vs. 0.8%, p=0.75), and abdominal retropubic urethropexy (0.2% vs.
261
0.1%, p=0.16) were similar between the two groups. No recurrent SUI was treated with an
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abdominovaginal vesical neck suspension, Kelly plication, cystourethroplasty or needle
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urethropexy.
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Other outcomes Patients operated on by higher-volume surgeons were no more likely to develop a UTI in
266 267
the 12 months postoperatively (23.5% vs. 24.1%, p=0.33) than those operated on by lower-
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volume surgeons. However, patients operated on by higher-volume surgeons were less likely to
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develop urinary retention requiring prolonged (beyond the first void trial visit, 2-4 days postop)
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catheterization (5.1% vs. 6.1%, p=0.02).
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Models Because some factors that may be associated with surgical failure or mesh
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removal/revision differed between those operated on by higher and lower-volume surgeons we
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performed modeling with a multivariate regression analysis. The risk ratio for reoperation
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comparing higher and lower-volume surgeons was 0.86 (p=0.04) in the unadjusted model and
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0.83 (p=0.01) in the adjusted model.
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Comment In this era of mesh litigation, safety warnings, and product withdrawals we found that
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among women with SUI who had surgery with a synthetic MUS implant, reoperation rates were
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low. However, we did find that even after adjusting for potential confounders, patients operated
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on by higher-volume surgeons (>40MUS/year) had a 17% lower rate of reoperation. While rates
285
of mesh removal/revision were similar between groups, rates of reoperation for SUI was 25%
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less likely in patients operated on by higher-volume surgeons. While mesh related complications
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were overall rare, patients operated on by higher-volume surgeons were over 42% less likely to
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receive another synthetic MUS.
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Evidence in prolapse mesh surgery,15 hysterectomy,16-18 and gynecology19 supports lower
290
reoperation rates in those patients operated on by higher volume surgeons. One retrospective
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Canadian study11 of 59,887 MUS procedures explored surgeon volume and a composite
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reoperation for mesh-related complication outcome. The study found that among patients of
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higher-volume surgeons (defined in their study as ≥75th %, >16 MUS/year) there was a
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significantly lower risk for the composite outcome (hazard ratio [HR], 0.73 [0.65-0.83]; absolute
295
risk reduction, 0.63% [0.36-0.92%%]; P<0.01). Like our study this composite outcome did
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include mesh removal and revision reoperations, however, unlike our study it did not include the
297
indications (such as urinary retention, mesh exposure, and pain). The results differ from ours, in
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that we did not find any differences in reoperation for mesh removal/revision between higher and
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lower-volume surgeons. However, it is difficult to compare the two studies in that the volume
300
cutoffs were different, no specific totals per indication for reoperation for complication are
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provided and no data on reoperation for SUI (and those overall reoperation) is reported. A
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second Canadian study20 found that after a surgeon 50 MUS/year their patients odds of mesh
303
revision declined, a finding that plateaued at 110 MUS/year. As this study found a nonlinear
304
result, and did not compare higher-volume to lower-volume surgeons directly it is hard to draw
305
comparisons. However we did find a similar cutoff of MUS/year to define higher-volume
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surgeons. An exhaustive search of Pubmed using MeSh terms (“Suburethral Slings,”
307
“reoperation,” “urinary incontinence, stress,” “recurrence”) and (“surgeon volume,” “surgeon
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experience,”) confirmed no other evidence regarding the impact of surgeon MUS volume on
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reoperation for SUI. Our results advance the literature on MUS and provide this data on
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reoperation for recurrent SUI after MUS.
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Despite small absolute risk reductions, our results do support the performance of MUS by
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a higher-volume surgeon. Advanced training through fellowship may be one avenue to obtain the
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experience needed to perform MUS and is supported by vaginal mesh regulatory notifications
314
and expert opinion.20-23 After this training is obtained, performing a higher-volume of MUS may
315
be needed to continue to perform the procedure with low complication and recurrent SUI rates.
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Furthermore, medical centers could consider having potential surgeons demonstrate a level of
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experience, training or volume prior to credentialing them to perform MUS.23
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Limitations
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This study has several limitations, many inherent to its retrospective design. Data was
321
entered into the medical record at the surgeon’s discretion and it is possible the indication for
322
reoperation could be miscoded or documented. However, the methods of this study as well as
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extensive verifications of data enhanced the ability to correctly report the indication for
324
reoperation. This study set out to report postoperative complications or SUI requiring reoperation
325
in the OR and thus could not detect complications or SUI managed conservatively (non-
326
operatively) in an office setting. By only reporting on patients who had reoperation, we
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minimized the risk of inaccurate coding that can occur in the office and thus the associated
328
overestimation of complications that can occur. While patients within the managed care
329
organization almost exclusively received care within the system, it is possible patients received
330
their primary MUS or reoperation outside of the system and thus would not be included in our
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study outcomes. Residual confounding is possible despite measuring and adjusting for several
332
covariates. For example, the degree of incontinence prior to the index MUS and repeat sling
333
could not be measured. Office urethral bulking procedures were not captured in our review, and
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thus there may be patients who received this as treatment for recurrent SUI who were not
335
accounted for in the study. Also, we did not assess intra-operative adverse events given these
336
events have been well characterized in other randomized controlled trials.24 Patients of higher-
337
volume surgeons were less likely to need prolonged catheterization, but no more likely to need a
338
reoperation for mesh removal/revision for urinary retention. While it is not clear why this
339
difference did not extend to reoperation, it is possible that the difference seen immediately
340
postoperative does not persist over time (thus not necessitating reoperation for mesh
341
removal/revision) or practice patterns may differ between patients operated on by these different
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volume surgeons.
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345 346
Strengths Our study has several strengths. This is a large ethnically diverse cohort study representing all MUS performed within a large managed care organization and thus captures the
347
reoperation rate of its patients. Our study captured data on a diverse group of surgeons operating
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at multiple medical centers, using a wide range of MUS approaches and MUS synthetic mesh
349
implants; therefore, representing typical practice patterns and enhancing generalizability.
350
Implants were linked to patient electronic medical records thus enhancing internal validity.
351
Multiple relevant covariates were available, and a multivariable analysis was performed to
352
confirm a statistically significant difference between higher and lower-volume surgeons. Data on
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the indication for mesh removal/revision was obtained consequently enhancing our
354
understanding of the reason behind the mesh removal.
355
356
357
Importance to clinical and patient care The implications for clinical care and patient safety of our study are significant. While
358
this study continues to demonstrate the overall low rates of reoperation rates following MUS in
359
both lower and higher volume surgeons, patients operated on by higher-volume surgeons have
360
lower overall rates of reoperation after MUS. This effect is seen most dramatically in reoperation
361
for SUI, where patients who have surgery with a higher-volume surgeon are 25% less likely to
362
have post-operative SUI that lead to reoperation. Similarly, patients who are operated on by
363
higher-volume surgeons are less likely to need prolonged postoperative catheterization. Within
364
our large managed care organization, we have continued to implement specialized pelvic floor
365
centers that result in more high-volume surgeons which we believe will continue to improve
366
surgical efficacy and safety. Our surgical efficacy and safety results can be considered by other
367
medical organizations seeking improvement in surgical outcomes.
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Acknowledgments: This research is supported by a grant from the Regional Research Committee
370
of Kaiser Permanente Southern California, Grant No. KP-RRC-20171101. The authors would
371
like to thank Stephanie Tovar for her coordination of support and resources at the regional
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research committee. The authors would like to thank Zoe Li for her assistance with database
373
creation and management. The authors would like to thank Dr. Michael Kanter and his team for
374
their assistance applying concentration curves to surgical volume and reoperation data. The
375
authors would like to thank Liz Walton-Paxton and her team for assistance with mesh implant
376
registry applications.
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1. Ulmsten U, Petros P. Intravaginal slingplasty (IVS): an ambulatory surgical procedure for treatment of female urinary incontinence. Scand J Urol Nephrol 1995;29:75-82. 2. Ford AA, Rogerson L, Cody JD, Aluko P, Ogah J. Mid-urethral sling operations for stress urinary incontinence in women. Cochrane Database Syst Rev 2017;7. 3. US Food & Drug Administration. Considerations about surgical mesh for SUI. https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsth etics/UroGynSurgicalMesh/ucm345219.htm. Accessed September 19, 2018. 4. Nilsson CG, Palva KR, Aarnio R, Morcos E, Falconer C. Seventeen years’ follow-up of the tension-free vaginal tape procedure for female stress urinary incontinence. Int Urogynecol J 2013;24:1265-1269. 5. Nager CW. Midurethral slings: evidence-based medicine vs. the medicolegal system. Am J Obstet Gynecol 2016;214:e1-5 6. Nguyen JN, Jakus-Waldman SM, Walter AJ, White T, Menefee SA. Perioperative Complications and Reoperations After Incontinence and Prolapse Surgeries Using Prosthetic Implants. Obstet Gynecol 2012;119:539-46. 7. Gurol-Urganci I, Geary RS, Mamza JB et al. Long-term rate of mesh sling removal following midurethral Mmesh sling insertion among women with stress urinary incontinence. JAMA 2018;320:1659-1669. 8. Berger AA, Tan-Kim J, Menefee S. Long-Term Risk of Reoperation after Synthetic Mesh Midurethral Sling Surgery for Stress Urinary Incontinence. Obstet Gynecol. Accepted in 2019 Dec Issue; In Press. 9. Funk MJ, Siddiqui NY, Pate V, Amundsen CL, Wu JM. Sling for mesh erosion and urinary retention: long-term risk and predictors. Am J Obstet Gynecol 2013;208(1):73.e1–73.e7.
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10. Mowat A, Maher C, Ballard E. Surgical outcomes for low-volume vs high-volume surgeons in gynecology surgery: a systematic review and meta-analysis. Am J Obstet Gynecol 2016;215:21-33. 11. Welk B, Al-Hothi A, Winick-Ng J. Removal or revision of vaginal mesh used in the treatment of stress urinary incontinence. JAMA Surg 2015;l150:1167-75. 12. Sung VW, Rogers ML, Myers DL, Clark MA. Impact of hospital and surgeon volumes on outcomes following pelvic reconstructive surgery in the United States. Am J Obstet Gynecol 2006;195:1778-83. 13. Gould MK, Tang T, Liu ILA, Lee J, Zheng C, Danforth KM et al. Recent trends in the identification of incidental pulmonary nodules. Am J Respir Crit Care Med 2015;192:1208-14. 14. Kanter MH, Huang YC, Kally Z, et al. Using concentration curves to assess organizationspecific relationships between surgeon volumes and outcomes. The Joint Commission Journal on Quality and Patient Safety 2018;44:321-327. 15. Kelly EC, Winick-Ng J, Welk B. Surgeon Experience and Complications of Transvaginal Prolapse Mesh. Obstet Gynecol 2016;128:65-71. 16. Boyd LR, Novetsky AP, Curtin JP. Effect of surgical volume on route of hysterectomy and short-term morbidity. Obstet Gynecol 2010;116:909–15.
436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470
17. Worley MJ Jr, Anwandter C, Sun CC et al. Impact of surgeon volume on patient safety in laparoscopic gynecologic surgery. Gynecol Oncol 2012;125:241-4. 18. Ruiz MP, Chen L, Hou JY et al. Outcomes of Hysterectomy Performed by Very LowVolume Surgeons. Obstet Gynecol 2018;131:981–990. 19. Mowat A, Maher C, Ballard E. Surgical outcomes for low-volume vs high-volume surgeons in gynecology surgery: a systematic review and meta-analysis. Am J Obstet Gynecol 2016;215:21-33. 20. Brennand EA, Quan H. Evaluation of the effect of surgeon’s operative volume and specialty on likelihood of revision after mesh midurethral sling placement. Obstet Gynecol 2019;133:1099-108. 21. US Food & Drug Administration. Urogynecologic surgical mesh: update on the safety and effectiveness of transvaginal placement for pelvic organ prolapse. http://www.fda.gov/downloads/medicaldevices/safety/alertsandnotices/UCM262760.pdf. Published 2011. Accessed February 11, 2018. 22. Chapple CR, Raz S, Brubaker L, Zimmern PE. Mesh sling in an era of uncertainty: lessons learned and the way forward. Eur Urol 2013;64(4):525-529. 23. American Urogynecologic Society. Position Statement on Restriction of Surgical Options for Pelvic Floor Disorders. https://www.augs.org/assets/1/6/Position_Statement_Surgical_Options_for_PFDs.pdf. Accessed December 1st 2018. 24. Richter HE, Albo ME, Zyczynski HM et al. Retropubic versus transobturator midurethral slings for stress incontinence. N Engl J Med 2010;362:2066–2076.
471
Tables/Figure Headings
472
Table 1: Demographics of subjects by volume of surgeon.
473
Table 2: Reoperation after MUS for higher vs. lower-volume surgeons.
474
Figure 1: Flowchart of cohort construction.
475 476
Figure 2: Concentration curve (55% of surgeries performed by lower volume surgeon’s accounted for 62% of the reoperations.)
477
Figure 3: Surgeon MUS volume distribution.
478 479 480
Total (n=13404)
MUS Surgery <=40 (N=7073)
MUS Surgery >40 (N=6331)
P value
Age Mean (SD) Age 20-39 40-59 60-79 80 and older
54.1 (11.69) yo 627 (8.9%) 4245 (60.0%) 2075 (29.3%) 126 (1.8%)
55.6 (11.94) yo 493 (7.8%) 3484 (55.0%) 2179 (34.4%) 175 (2.8%)
<0.0001 <0.0001
Ethnicity Hispanic White Asian/Pacific Island Black Others Unknown
<0.0001 3917 (55.4%) 2452 (34.7%) 373 (5.3%) 277 (3.9%) 47(0.7%) 7 (0.1%)
3044 (48.1%) 2789 (44.1%) 239 (3.8%) 197 (3.1%) 47(0.7%) 15 (0.2%)
Marital Status Married/Dom Partner Divorced/Separated Single Widowed Unknown
0.0327 5867 (68.8%) 977 (13.8%) 649 (9.2%) 562 (7.9%) 18 (0.3%)
4323 (68.3%) 831 (13.1%) 563 (8.9%) 599 (9.5%) 15 (0.2%)
BMI Mean (SD) BMI <25 25-29.99 30-34.99 35 and higher unknown
29.5 (5.40) 1446 (20.4%) 2716 (38.4%) 1842 (26.0%) 1063 (15.0%) 6 (0.1%)
29.5 (5.58) 1390 (21.9%) 2326 (36.7%) 1554 (25.6%) 1017 (16.1%) 4 (0.1%)
0.7253 0.0508
Smokers
365 (5.2%)
243 (3.8%)
<0.0001
Parity Median (Iqr)
3 (2,4)
3 (2,4)
0.3200
Diabetes
927 (13.1%)
849 (13.4%)
0.6042
Post-Menopausal
4186 (59.2%)
4113 (65.0%)
<0.0001
Type of MUS Retropubic Transobturator Single-Incision
4392 (62.1%) 2370 (33.5%) 311 (4.4%)
4065 (64.2%) 1241(19.6%) 1025 (16.2%)
<0.0001
Total (n=13404)
MUS Surgery <=40 (N=7073)
MUS Surgery >40 (N=6331)
P value
Overall Reoperation Mesh Removal/Revision Surgical Failure
296 (4.2%) 64 (0.9%) 256 (3.6%)
225 (3.6%) 68 (1.1%) 170 (2.7%)
0.0414
Reoperation for Mesh Removal/Revision Urinary Retention Mesh Exposure Pain Bleeding Infection Nerve Injury Retropubic Hematoma Bladder/Urethral Injury Bowel Injury
64 (0.9%) 44 (0.6%) 18 (0.3%) 8 (0.1%) 2 (0.0%) 3 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
68 (1.1%) 57 (0.9%) 11 (0.2%) 5 (0.1%) 6 (0.1%) 1 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
0.3219 0.0629 0.3152 0.5263 0.1156 0.3730
Reoperation for SUI MUS Bulking Injection Laparoscopic Burch Burch Abdominovag. Ves.Neck Susp. Kelly Plication Cystourethroplasty Needle Urethropexy
256 (3.6%) 178 (2.5%) 60 (0.8%) 21 (0.3%) 7 (0.1%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
170 (2.7%) 98 (1.5%) 57 (0.9%) 3 (0.0%) 12 (0.2%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
0.0021 <0.0001 0.7464 0.0006 0.1641
S0002-9378(19)31111-1
DOI:
https://doi.org/10.1016/j.ajog.2019.09.006
Reference:
YMOB 12877
To appear in:
American Journal of Obstetrics and Gynecology
Received Date: 31 December 2018 Revised Date:
4 September 2019
Accepted Date: 10 September 2019
Please cite this article as: Berger AA, Tan-Kim J, Menefee SA, Surgeon Volume and Reoperation Risk after Midurethral Sling, American Journal of Obstetrics and Gynecology (2019), doi: https:// doi.org/10.1016/j.ajog.2019.09.006. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Elsevier Inc. All rights reserved.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Surgeon Volume and Reoperation Risk after Midurethral Sling Alexander A. Berger MD MPH,1,2 Jasmine Tan-Kim MD,1 Shawn A. Menefee MD1
41
Word Count: Abstract-420, Manuscript-2738
1
Division of Female Pelvic Medicine and Reconstructive Surgery, Department of OB/GYN, Kaiser Permanente-San Diego 2
Division of Female Pelvic Medicine and Reconstructive Surgery, Department of Obstetrics, Gynecology and Reproductive Science, University of California San Diego
Corresponding Author: Alexander A. Berger MD MPH 3250 Fordham Street, Bldg A, Ob/Gyn Department, San Diego, CA 92110 Phone: 858-534-8930 Email: [email protected] Email: [email protected] Conflicts of interest: A.A.B.: None, J.T.K.: None, S.A.M.: None. The research is supported by a grant from the Regional Research Committee of Kaiser Permanente Southern California, Grant No. KP-RRC-20171101. The granting organization had no role in the study design, data collection, analysis and interpretation of data, writing of manuscript or decision to submit the article for publication. This work was accepted as an oral presentation at the 45th Annual Meeting of the Society of Gynecologic Surgeons (Tuscon AR, March 2019).
Condensation: Higher volume surgeons have lower reoperation rates after midurethral sling surgery. Short Title: Surgeon volume and reoperation after midurethral sling.
42
AJOG at a Glance
43
A. Why was this study conducted?
44
To measure the impact of a surgeon’s procedural volume on their patient’s rate of reoperation
45
after midurethral sling surgery.
46
47
B. What are the key findings?
48
While reoperation rates were low for both higher and lower-volume surgeons, higher-volume
49
surgeons have lower overall rates of reoperation after midurethral sling. This effect is seen most
50
dramatically in reoperation for surgical failure, where patients who have surgery with a higher-
51
volume surgeon are 25% less likely to have post-operative stress urinary incontinence leading to
52
reoperation.
53 54
C. What does this study add to what is already known?
55
Mesh litigation and warnings are increasingly impacting the availability of and comfort with
56
midurethral slings for stress urinary incontinence. This paper adds to the growing literature on
57
safety and efficacy of midurethral slings and shows that higher volume surgeons consistently
58
have lower reoperation rates. This supports the continued use of midurethral slings and efforts to
59
promote highly trained, experienced surgeon’s performing the procedures.
60 61 62
63
Structured Abstract
64
Background: Emerging research supports that fewer complications occur in patients operated on
65
by higher surgical volume surgeons. The midurethral sling has been involved in recent warnings
66
and litigation, further supporting a need to understand features that enhance its safety and
67
efficacy.
68
Objective: To measure the impact of a surgeon’s volume on their patient’s rate of reoperation
69
after midurethral sling surgery.
70
Study Design: This is a retrospective cohort study evaluating all surgeons performing synthetic
71
mesh midurethral sling procedures for stress urinary incontinence at a large managed care
72
organization with over 4.5 million members from 2005 to 2016. Physicians’ CPT and ICD-9/10
73
codes were used to identify the procedures and reoperations performed. The system-wide
74
medical record was queried for demographic and perioperative data. The primary outcome was
75
the overall reoperation rate after midurethral sling. Concentration curves (figure 2) were used to
76
identify the impact of a surgeon’s surgical volume on their rate of reoperation. Demographics,
77
characteristics, and reoperation of patients were compared using chi-square for categorical
78
variables and Wilcoxon rank sum for continuous variables. Poisson regression models with a
79
robust error variance were used to calculate the unadjusted and the adjusted risk ratios of
80
reoperation using age, body mass index, marital status, race, parity, vaginal estrogen use, sling
81
type, smoking, diabetes, and menopausal status as covariates.
82
Results: 227 surgeons performed 13,404 midurethral slings over the study period and patients
83
had a mean of 4.4 years of follow up. Higher-volume surgeons (>40 procedures/year, ≥95th
84
percentile) performed 47% of surgeries in this cohort and had overall lower rate of reoperation
85
(3.6% vs. 4.2%,95% CI 0.67, 0.94 (p=0.04)) compared to lower-volume surgeons. Higher-
86
volume surgeons had a lower rate of reoperation for surgical failure (2.7% vs. 3.6%, 95% CI
87
0.55-0.92 (p<0.01)). Rates of reoperation for complications were similar between the two groups
88
(1.1% vs. 0.9%,95% CI 0.82-1.13(p=0.32)). For patients requiring a reoperation secondary to
89
complication, rates of reoperation for urinary retention (0.9% vs. 0.6%,p=0.06), mesh exposure
90
(0.2% vs. 0.3%,p=0.31), hemorrhage/bleeding (0.1% vs. 0.0%,p=0.11), pain (0.1% vs.
91
0.1%,p=0.52), and infection (0.0% vs. 0.0%,p=0.37) did not differ between higher and lower-
92
volume surgeons. The risk ratio for reoperation comparing higher and lower-volume surgeons
93
was 0.83 (95% CI 0.67,0.98 (p=0.01)) in the adjusted model.
94
Conclusions: While reoperation rates were low for both higher and lower-volume surgeons,
95
higher-volume surgeons have lower overall rates of reoperation after midurethral sling. This
96
effect is seen most dramatically in reoperation for surgical failure, where patients who have
97
surgery with a higher-volume surgeon are 25% less likely to have post-operative stress urinary
98
incontinence leading to reoperation.
99 100 101 102 103 104 105 106 107 108
Key Words: Midurethral slings, surgeon volume, reoperation, safety, efficacy.
109
Introduction
110
Midurethral slings (MUS) were developed in the mid-1990s1 and have become the most
111
commonly used surgical treatment worldwide for stress urinary incontinence (SUI), a condition
112
that affects 1 in 3 adult women throughout their lives.2 Approximately 250,000 MUS surgeries
113
are performed annually in the United States.3 The MUS involves the placement of 1 cm wide
114
ribbon of polypropylene mesh under the mid-urethra. MUS has the same treatment success rates,
115
but less morbidity than suburethral fascial slings and open retropubic colposuspension, two
116
traditional procedures. For example, women undergoing MUS have short-term cure rates of 62-
117
98% and the advantage of fewer perioperative complications, take less operating room (OR)
118
time, have shorter hospital stays, lower rates of venous thromboembolism (VTE), and have lower
119
bladder perforations compared to the open retropubic colposuspension.2 Furthermore, success
120
after MUS has been shown to be long lasting with a subjective cure rate as high as 87% after 17-
121
years of followup.4
122
In 2011, the Food and Drug Administration (FDA) published a safety communication
123
regarding the use of transvaginal mesh for pelvic organ prolapse (POP). This statement was in
124
response to concerns over surgical complications involving the use of mesh in these patients.5
125
While the FDA specifically excluded MUS mesh in its 2011 report as well as their 2013 and
126
2016 updated classifications, the medicolegal community has grouped the two together in their
127
litigation efforts. In the United States more than 50,000 women have joined class action lawsuits
128
for transvaginal mesh complications resulting from SUI and prolapse procedures.5 Secondary to
129
the public and financial pressures, several companies (Endo International, Astora) that supply
130
MUS have stopped producing them.5 While additional long-term data is needed2,5,6 overall
131
reoperation after MUS surgery is uncommon. Work from our group and other large retrospective
132
studies have found a rate of any reoperation of 4.5-5.5%,7-8 while reoperation for recurrent SUI
133
and MUS mesh removal was 3.5-3.9%7-8 and 1.0-3.4%7-9 respectively at 5 years.
134
Emerging research is supporting that fewer complications occur in patients operated on
135
by high surgical volume surgeons.10-12 A recent systematic review of gynecologic surgeries
136
found that a low-volume surgeon (defined in that study as performing a procedure once a month
137
or less) had a 1.3 odds ratio of complications compared to those who performed procedures more
138
frequently.10 After placement of MUS there was a 37% increase in risk of reoperation for mesh
139
removal/revision for low volume surgeons (defined as the bottom three quartiles or <16
140
MUS/year) in a Canadian study.11 With additional evidence in MUS, surgeon volume could be
141
considered as a component of enhancing the safety and efficacy of MUS.
142 143
144 145 146 147 148 149 150 151 152
Our objective was to study whether women who underwent MUS for SUI by highvolume surgeons have lower incidence of reoperations for adverse events and recurrent SUI.
153
154
Materials and Methods This is a sub-analysis of a retrospective cohort study8 evaluating all surgeons performing
155
synthetic mesh MUS for SUI at a large managed care organization (with currently over 4.5
156
million members) from 2005 to 2016. The study was approved by the Kaiser Southern California
157
IRB (#11508). Patients within the Kaiser system obtain all healthcare, with rare exception,
158
within this system and have a high retention rate.13 The system-wide medical record and linked
159
surgical database (HealthConnect Clarity) was queried and an algorithm was created to obtain
160
patient data regarding primary MUS and reoperation, as well as demographic and perioperative
161
data using physicians’ CPT and ICD-9/10 codes. The primary outcome (overall reoperation rate
162
after MUS) as well as secondary outcomes (specific reoperation rates for surgical failure and
163
complications) were assessed. Types of reoperation for complication assessed with urinary
164
retention, mesh exposure, pain, bleeding, infection, nerve injury, retropubic hematoma,
165
bladder/urethral injury, and bowel injury. Intraoperative complications were excluded. Types of
166
reoperation for surgical failure were assessed and included repeat MUS, bulking injection,
167
laparoscopic and open retropubic urethropexy, abdominovaginal vesical neck suspension, Kelly
168
plication, cystourethropasty and needle urethropexy. Additionally, the postoperative
169
complications of urinary tract infection (UTI) (defined as symptoms and greater than 105 colony
170
forming units on urine culture), recurrent UTI, and urinary retention were assessed.
171
With the assistance of the Kaiser Permanente National Implant Registry, surgical implant
172
logs containing the product name, product number and manufacturer, as well as additional codes
173
were used to identify the MUS implants used. Subjects demographic and clinical data, including
174
age, ethnicity, marital status, body mass index (BMI, calculated as weight (kg)/[height (m)]2),
175
smoking status, parity, presence or absence of diabetes, post-menopausal status, and estrogen use
176
were obtained. MUS implants were classified as retropubic, transobturator, or single incision.
177
Medical records and operative reports of patients with multiple implants and reoperations were
178
reviewed individually to verify the algorithm correctly identified the implant and instances of
179
reoperation. Validation measures were implemented, and the accuracy of data abstraction was
180
verified in a sample of subjects as well as those subjects with reoperation and appropriate
181
modifications were made to ensure internal validity. Subjects in which data could not be verified
182
or were missing were excluded.
183
Surgeon MUS volume, the primary exposure of interest was classified with the use of the
184
linked databases and unique physician identifiers. With the assistance of the Kaiser Southern
185
California Quality and Clinical Analysis group, concentration curves14 were used to identify the
186
impact of a surgeon’s surgical volume on their rate of reoperation. Cumulative percentage of
187
MUS ranked from lowest to highest on annual surgeon procedure volumes were plotted on the X
188
axis while cumulative percentage of reoperations were plotted on the Y-axis. The 45-degree line
189
of equality represents reoperations that are dispersed equally across surgeons with a range of
190
MUS surgical volumes. Curves above this line indicate reoperations occurring disproportionately
191
among lower-volume surgeons. A concentration index (CI) was then used to assess the summary
192
measurement of inequality in reoperation rate.
193
All analyses were performed using SAS 9.4(SAS Institute Inc., Cary, North Carolina).
194
Demographics, characteristics, and reoperation of patients operated by higher and lower-volume
195
surgeons were compared using chi-square for categorical variables and Wilcoxon rank sum for
196
continuous variables. Poisson regression models with a robust error variance were used to
197
calculate the unadjusted and the adjusted risk ratios of reoperation using age, BMI, marital
198
status, race, parity, vaginal estrogen use, sling type, smoking, diabetes, and menopausal status as
199
covariates.
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
Results
217
Demographics of the cohort
218
From 2005 to 2016 we identified 17,030 women who underwent a primary synthetic
219
MUS for SUI within the health system of which 13,404 had identifiable surgeon and could be
220
reliably classified into the higher and lower volume groups (Figure 1). The mean follow-up was
221
4.4 (SD 2.77) years and did not differ between patients operated on by higher and lower-volume
222
surgeons. Demographics are presented in Table 1 and differences between those operated on by
223
higher and lower-volume surgeons are noted. Patients operated on by higher-volume surgeons
224
were older (mean and SD age 55.6 (11.9) vs. 54.1 (11.7) years old, p<0.01), more likely to be
225
white (p<0.01), widowed (p=0.03), more likely to have a single incision sling (16.2% vs. 4.4%,
226
p<0.01), and be post-menopausal (65.0% vs. 59.2%, p<0.01) while also being less likely a
227
smoker (3.8 vs. 5.2%, p<0.01).
228
229
Demographics of the surgeons
230
The surgeries were performed by 227 unique surgeons, with a range of 11 to 167
231
surgeons performing MUS in a given year. More surgeons performed MUS over time. Surgeons
232
performed 1 to 135 MUS in a given year, with a mean volume of 10, and most performing ≤10
233
MUS per year (Figure 3). The concentration curve was examined, and we found that at the ≥95%
234
(>40MUS/year) there was a statistically significant difference in reoperation rate. The higher-
235
volume surgeons (>40 MUS/year) performed 47% (7073/13404) of the MUS in the cohort. Most
236
higher volume surgeons were fellowship (75%) and gynecology (87%) trained.
237
238
Reoperation Results Patients operated on by higher-volume surgeons had a lower rate of all-cause reoperation
239
(3.6% vs. 4.2%, p=0.04) compared to those operated on by lower-volume surgeons (Table 2).
240
This is a relative risk of 0.86 and absolute risk reduction of 0.6% reoperation for patients
241
operated on by higher-volume surgeons.
242 243
244
Reoperation for mesh revision/removal secondary to complication results The rate of MUS mesh sling removal/revision was similar between those patients
245
operated on by higher and lower-volume surgeons (1.1% vs. 0.9%,p=0.32). For patients
246
requiring a reoperation to remove or revise their MUS mesh sling, rates of sling removal for
247
urinary retention (0.9% vs. 0.6%,p=0.06), mesh exposure (0.2% vs. 0.3%,p=0.31), pain (0.1%
248
vs. 0.1%,p=0.52), hemorrhage/bleeding (0.1% vs. 0.0%,p=0.11), and infection (0.0% vs.
249
0.0%,p=0.37) did not differ between higher and lower-volume surgeons. There were no cases of
250
MUS mesh sling removal/revision for nerve injury, retropubic hematoma, bladder, urethral, or
251
bowel injury during the study period.
252
253
254
Reoperation for surgical failure Patients operated on by higher-volume surgeons for their primary MUS had a lower rate
255
of reoperation for SUI (2.7% vs. 3.6%,p<0.01). This is a relative risk of 0.75 and absolute risk
256
reduction of 0.9% reoperation for patients operated on by higher-volume surgeons. When
257
compared with patients operated on by lower-volume surgeons, patients operated on by higher-
258
volume surgeons had a lower rate of repeat MUS (1.5% vs. 2.5%,p<0.01) and laparoscopic
259
retropubic urethropexy (0.0% vs. 0.3%,p<0.01). Rates of treatment for SUI after primary MUS
260
by bulking injections (0.9% vs. 0.8%, p=0.75), and abdominal retropubic urethropexy (0.2% vs.
261
0.1%, p=0.16) were similar between the two groups. No recurrent SUI was treated with an
262
abdominovaginal vesical neck suspension, Kelly plication, cystourethroplasty or needle
263
urethropexy.
264
265
Other outcomes Patients operated on by higher-volume surgeons were no more likely to develop a UTI in
266 267
the 12 months postoperatively (23.5% vs. 24.1%, p=0.33) than those operated on by lower-
268
volume surgeons. However, patients operated on by higher-volume surgeons were less likely to
269
develop urinary retention requiring prolonged (beyond the first void trial visit, 2-4 days postop)
270
catheterization (5.1% vs. 6.1%, p=0.02).
271
272
273
Models Because some factors that may be associated with surgical failure or mesh
274
removal/revision differed between those operated on by higher and lower-volume surgeons we
275
performed modeling with a multivariate regression analysis. The risk ratio for reoperation
276
comparing higher and lower-volume surgeons was 0.86 (p=0.04) in the unadjusted model and
277
0.83 (p=0.01) in the adjusted model.
278
279
280
281
Comment In this era of mesh litigation, safety warnings, and product withdrawals we found that
282
among women with SUI who had surgery with a synthetic MUS implant, reoperation rates were
283
low. However, we did find that even after adjusting for potential confounders, patients operated
284
on by higher-volume surgeons (>40MUS/year) had a 17% lower rate of reoperation. While rates
285
of mesh removal/revision were similar between groups, rates of reoperation for SUI was 25%
286
less likely in patients operated on by higher-volume surgeons. While mesh related complications
287
were overall rare, patients operated on by higher-volume surgeons were over 42% less likely to
288
receive another synthetic MUS.
289
Evidence in prolapse mesh surgery,15 hysterectomy,16-18 and gynecology19 supports lower
290
reoperation rates in those patients operated on by higher volume surgeons. One retrospective
291
Canadian study11 of 59,887 MUS procedures explored surgeon volume and a composite
292
reoperation for mesh-related complication outcome. The study found that among patients of
293
higher-volume surgeons (defined in their study as ≥75th %, >16 MUS/year) there was a
294
significantly lower risk for the composite outcome (hazard ratio [HR], 0.73 [0.65-0.83]; absolute
295
risk reduction, 0.63% [0.36-0.92%%]; P<0.01). Like our study this composite outcome did
296
include mesh removal and revision reoperations, however, unlike our study it did not include the
297
indications (such as urinary retention, mesh exposure, and pain). The results differ from ours, in
298
that we did not find any differences in reoperation for mesh removal/revision between higher and
299
lower-volume surgeons. However, it is difficult to compare the two studies in that the volume
300
cutoffs were different, no specific totals per indication for reoperation for complication are
301
provided and no data on reoperation for SUI (and those overall reoperation) is reported. A
302
second Canadian study20 found that after a surgeon 50 MUS/year their patients odds of mesh
303
revision declined, a finding that plateaued at 110 MUS/year. As this study found a nonlinear
304
result, and did not compare higher-volume to lower-volume surgeons directly it is hard to draw
305
comparisons. However we did find a similar cutoff of MUS/year to define higher-volume
306
surgeons. An exhaustive search of Pubmed using MeSh terms (“Suburethral Slings,”
307
“reoperation,” “urinary incontinence, stress,” “recurrence”) and (“surgeon volume,” “surgeon
308
experience,”) confirmed no other evidence regarding the impact of surgeon MUS volume on
309
reoperation for SUI. Our results advance the literature on MUS and provide this data on
310
reoperation for recurrent SUI after MUS.
311
Despite small absolute risk reductions, our results do support the performance of MUS by
312
a higher-volume surgeon. Advanced training through fellowship may be one avenue to obtain the
313
experience needed to perform MUS and is supported by vaginal mesh regulatory notifications
314
and expert opinion.20-23 After this training is obtained, performing a higher-volume of MUS may
315
be needed to continue to perform the procedure with low complication and recurrent SUI rates.
316
Furthermore, medical centers could consider having potential surgeons demonstrate a level of
317
experience, training or volume prior to credentialing them to perform MUS.23
318
319
Limitations
320
This study has several limitations, many inherent to its retrospective design. Data was
321
entered into the medical record at the surgeon’s discretion and it is possible the indication for
322
reoperation could be miscoded or documented. However, the methods of this study as well as
323
extensive verifications of data enhanced the ability to correctly report the indication for
324
reoperation. This study set out to report postoperative complications or SUI requiring reoperation
325
in the OR and thus could not detect complications or SUI managed conservatively (non-
326
operatively) in an office setting. By only reporting on patients who had reoperation, we
327
minimized the risk of inaccurate coding that can occur in the office and thus the associated
328
overestimation of complications that can occur. While patients within the managed care
329
organization almost exclusively received care within the system, it is possible patients received
330
their primary MUS or reoperation outside of the system and thus would not be included in our
331
study outcomes. Residual confounding is possible despite measuring and adjusting for several
332
covariates. For example, the degree of incontinence prior to the index MUS and repeat sling
333
could not be measured. Office urethral bulking procedures were not captured in our review, and
334
thus there may be patients who received this as treatment for recurrent SUI who were not
335
accounted for in the study. Also, we did not assess intra-operative adverse events given these
336
events have been well characterized in other randomized controlled trials.24 Patients of higher-
337
volume surgeons were less likely to need prolonged catheterization, but no more likely to need a
338
reoperation for mesh removal/revision for urinary retention. While it is not clear why this
339
difference did not extend to reoperation, it is possible that the difference seen immediately
340
postoperative does not persist over time (thus not necessitating reoperation for mesh
341
removal/revision) or practice patterns may differ between patients operated on by these different
342
volume surgeons.
343
344
345 346
Strengths Our study has several strengths. This is a large ethnically diverse cohort study representing all MUS performed within a large managed care organization and thus captures the
347
reoperation rate of its patients. Our study captured data on a diverse group of surgeons operating
348
at multiple medical centers, using a wide range of MUS approaches and MUS synthetic mesh
349
implants; therefore, representing typical practice patterns and enhancing generalizability.
350
Implants were linked to patient electronic medical records thus enhancing internal validity.
351
Multiple relevant covariates were available, and a multivariable analysis was performed to
352
confirm a statistically significant difference between higher and lower-volume surgeons. Data on
353
the indication for mesh removal/revision was obtained consequently enhancing our
354
understanding of the reason behind the mesh removal.
355
356
357
Importance to clinical and patient care The implications for clinical care and patient safety of our study are significant. While
358
this study continues to demonstrate the overall low rates of reoperation rates following MUS in
359
both lower and higher volume surgeons, patients operated on by higher-volume surgeons have
360
lower overall rates of reoperation after MUS. This effect is seen most dramatically in reoperation
361
for SUI, where patients who have surgery with a higher-volume surgeon are 25% less likely to
362
have post-operative SUI that lead to reoperation. Similarly, patients who are operated on by
363
higher-volume surgeons are less likely to need prolonged postoperative catheterization. Within
364
our large managed care organization, we have continued to implement specialized pelvic floor
365
centers that result in more high-volume surgeons which we believe will continue to improve
366
surgical efficacy and safety. Our surgical efficacy and safety results can be considered by other
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medical organizations seeking improvement in surgical outcomes.
368
369
Acknowledgments: This research is supported by a grant from the Regional Research Committee
370
of Kaiser Permanente Southern California, Grant No. KP-RRC-20171101. The authors would
371
like to thank Stephanie Tovar for her coordination of support and resources at the regional
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research committee. The authors would like to thank Zoe Li for her assistance with database
373
creation and management. The authors would like to thank Dr. Michael Kanter and his team for
374
their assistance applying concentration curves to surgical volume and reoperation data. The
375
authors would like to thank Liz Walton-Paxton and her team for assistance with mesh implant
376
registry applications.
377
378 379 380 381 382 383 384 385 386 387 388 389 390 391 392
393
References
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1. Ulmsten U, Petros P. Intravaginal slingplasty (IVS): an ambulatory surgical procedure for treatment of female urinary incontinence. Scand J Urol Nephrol 1995;29:75-82. 2. Ford AA, Rogerson L, Cody JD, Aluko P, Ogah J. Mid-urethral sling operations for stress urinary incontinence in women. Cochrane Database Syst Rev 2017;7. 3. US Food & Drug Administration. Considerations about surgical mesh for SUI. https://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsth etics/UroGynSurgicalMesh/ucm345219.htm. Accessed September 19, 2018. 4. Nilsson CG, Palva KR, Aarnio R, Morcos E, Falconer C. Seventeen years’ follow-up of the tension-free vaginal tape procedure for female stress urinary incontinence. Int Urogynecol J 2013;24:1265-1269. 5. Nager CW. Midurethral slings: evidence-based medicine vs. the medicolegal system. Am J Obstet Gynecol 2016;214:e1-5 6. Nguyen JN, Jakus-Waldman SM, Walter AJ, White T, Menefee SA. Perioperative Complications and Reoperations After Incontinence and Prolapse Surgeries Using Prosthetic Implants. Obstet Gynecol 2012;119:539-46. 7. Gurol-Urganci I, Geary RS, Mamza JB et al. Long-term rate of mesh sling removal following midurethral Mmesh sling insertion among women with stress urinary incontinence. JAMA 2018;320:1659-1669. 8. Berger AA, Tan-Kim J, Menefee S. Long-Term Risk of Reoperation after Synthetic Mesh Midurethral Sling Surgery for Stress Urinary Incontinence. Obstet Gynecol. Accepted in 2019 Dec Issue; In Press. 9. Funk MJ, Siddiqui NY, Pate V, Amundsen CL, Wu JM. Sling for mesh erosion and urinary retention: long-term risk and predictors. Am J Obstet Gynecol 2013;208(1):73.e1–73.e7.
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10. Mowat A, Maher C, Ballard E. Surgical outcomes for low-volume vs high-volume surgeons in gynecology surgery: a systematic review and meta-analysis. Am J Obstet Gynecol 2016;215:21-33. 11. Welk B, Al-Hothi A, Winick-Ng J. Removal or revision of vaginal mesh used in the treatment of stress urinary incontinence. JAMA Surg 2015;l150:1167-75. 12. Sung VW, Rogers ML, Myers DL, Clark MA. Impact of hospital and surgeon volumes on outcomes following pelvic reconstructive surgery in the United States. Am J Obstet Gynecol 2006;195:1778-83. 13. Gould MK, Tang T, Liu ILA, Lee J, Zheng C, Danforth KM et al. Recent trends in the identification of incidental pulmonary nodules. Am J Respir Crit Care Med 2015;192:1208-14. 14. Kanter MH, Huang YC, Kally Z, et al. Using concentration curves to assess organizationspecific relationships between surgeon volumes and outcomes. The Joint Commission Journal on Quality and Patient Safety 2018;44:321-327. 15. Kelly EC, Winick-Ng J, Welk B. Surgeon Experience and Complications of Transvaginal Prolapse Mesh. Obstet Gynecol 2016;128:65-71. 16. Boyd LR, Novetsky AP, Curtin JP. Effect of surgical volume on route of hysterectomy and short-term morbidity. Obstet Gynecol 2010;116:909–15.
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17. Worley MJ Jr, Anwandter C, Sun CC et al. Impact of surgeon volume on patient safety in laparoscopic gynecologic surgery. Gynecol Oncol 2012;125:241-4. 18. Ruiz MP, Chen L, Hou JY et al. Outcomes of Hysterectomy Performed by Very LowVolume Surgeons. Obstet Gynecol 2018;131:981–990. 19. Mowat A, Maher C, Ballard E. Surgical outcomes for low-volume vs high-volume surgeons in gynecology surgery: a systematic review and meta-analysis. Am J Obstet Gynecol 2016;215:21-33. 20. Brennand EA, Quan H. Evaluation of the effect of surgeon’s operative volume and specialty on likelihood of revision after mesh midurethral sling placement. Obstet Gynecol 2019;133:1099-108. 21. US Food & Drug Administration. Urogynecologic surgical mesh: update on the safety and effectiveness of transvaginal placement for pelvic organ prolapse. http://www.fda.gov/downloads/medicaldevices/safety/alertsandnotices/UCM262760.pdf. Published 2011. Accessed February 11, 2018. 22. Chapple CR, Raz S, Brubaker L, Zimmern PE. Mesh sling in an era of uncertainty: lessons learned and the way forward. Eur Urol 2013;64(4):525-529. 23. American Urogynecologic Society. Position Statement on Restriction of Surgical Options for Pelvic Floor Disorders. https://www.augs.org/assets/1/6/Position_Statement_Surgical_Options_for_PFDs.pdf. Accessed December 1st 2018. 24. Richter HE, Albo ME, Zyczynski HM et al. Retropubic versus transobturator midurethral slings for stress incontinence. N Engl J Med 2010;362:2066–2076.
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Tables/Figure Headings
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Table 1: Demographics of subjects by volume of surgeon.
473
Table 2: Reoperation after MUS for higher vs. lower-volume surgeons.
474
Figure 1: Flowchart of cohort construction.
475 476
Figure 2: Concentration curve (55% of surgeries performed by lower volume surgeon’s accounted for 62% of the reoperations.)
477
Figure 3: Surgeon MUS volume distribution.
478 479 480
Total (n=13404)
MUS Surgery <=40 (N=7073)
MUS Surgery >40 (N=6331)
P value
Age Mean (SD) Age 20-39 40-59 60-79 80 and older
54.1 (11.69) yo 627 (8.9%) 4245 (60.0%) 2075 (29.3%) 126 (1.8%)
55.6 (11.94) yo 493 (7.8%) 3484 (55.0%) 2179 (34.4%) 175 (2.8%)
<0.0001 <0.0001
Ethnicity Hispanic White Asian/Pacific Island Black Others Unknown
<0.0001 3917 (55.4%) 2452 (34.7%) 373 (5.3%) 277 (3.9%) 47(0.7%) 7 (0.1%)
3044 (48.1%) 2789 (44.1%) 239 (3.8%) 197 (3.1%) 47(0.7%) 15 (0.2%)
Marital Status Married/Dom Partner Divorced/Separated Single Widowed Unknown
0.0327 5867 (68.8%) 977 (13.8%) 649 (9.2%) 562 (7.9%) 18 (0.3%)
4323 (68.3%) 831 (13.1%) 563 (8.9%) 599 (9.5%) 15 (0.2%)
BMI Mean (SD) BMI <25 25-29.99 30-34.99 35 and higher unknown
29.5 (5.40) 1446 (20.4%) 2716 (38.4%) 1842 (26.0%) 1063 (15.0%) 6 (0.1%)
29.5 (5.58) 1390 (21.9%) 2326 (36.7%) 1554 (25.6%) 1017 (16.1%) 4 (0.1%)
0.7253 0.0508
Smokers
365 (5.2%)
243 (3.8%)
<0.0001
Parity Median (Iqr)
3 (2,4)
3 (2,4)
0.3200
Diabetes
927 (13.1%)
849 (13.4%)
0.6042
Post-Menopausal
4186 (59.2%)
4113 (65.0%)
<0.0001
Type of MUS Retropubic Transobturator Single-Incision
4392 (62.1%) 2370 (33.5%) 311 (4.4%)
4065 (64.2%) 1241(19.6%) 1025 (16.2%)
<0.0001
Total (n=13404)
MUS Surgery <=40 (N=7073)
MUS Surgery >40 (N=6331)
P value
Overall Reoperation Mesh Removal/Revision Surgical Failure
296 (4.2%) 64 (0.9%) 256 (3.6%)
225 (3.6%) 68 (1.1%) 170 (2.7%)
0.0414
Reoperation for Mesh Removal/Revision Urinary Retention Mesh Exposure Pain Bleeding Infection Nerve Injury Retropubic Hematoma Bladder/Urethral Injury Bowel Injury
64 (0.9%) 44 (0.6%) 18 (0.3%) 8 (0.1%) 2 (0.0%) 3 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
68 (1.1%) 57 (0.9%) 11 (0.2%) 5 (0.1%) 6 (0.1%) 1 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
0.3219 0.0629 0.3152 0.5263 0.1156 0.3730
Reoperation for SUI MUS Bulking Injection Laparoscopic Burch Burch Abdominovag. Ves.Neck Susp. Kelly Plication Cystourethroplasty Needle Urethropexy
256 (3.6%) 178 (2.5%) 60 (0.8%) 21 (0.3%) 7 (0.1%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
170 (2.7%) 98 (1.5%) 57 (0.9%) 3 (0.0%) 12 (0.2%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%)
0.0021 <0.0001 0.7464 0.0006 0.1641