Bariatric surgery outcomes when assisted by fellows and residents: an MBSAQIP analysis of 477,670 patients

Surgery for Obesity and Related Diseases - (2020) 1–7

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Original article

Bariatric surgery outcomes when assisted by fellows and residents: an MBSAQIP analysis of 477,670 patients Selwan D. Barbat, M.D.a, Kyle J. Thompson, Ph.D.b, Enayetur Raheem, Ph.D.b, Iain H. Mckillop, Ph.D.b, Nicholas Dugan, M.D.a, Abdelrahman Nimeri, M.D.a,*

Q11

b

a Division of Bariatric Surgery, Department of Surgery, Carolinas Medical Center, Charlotte, North Carolina Carolinas Center for Clinical Outcomes Science, Department of Surgery, Carolinas Medical Center, Charlotte, North Carolina

Received 24 July 2019; accepted 14 January 2020

Q1

Abstract

Q2 Key words:

Background: Previous reports of bariatric surgery outcomes when cases are assisted by residents and/or fellows have been inconclusive. Objective: To compare bariatric surgery outcomes for cases with surgical trainees (ST; residents and fellows) versus nonsurgical trainees (nST; all other assistants) using the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) Registry. Setting: - - Methods: The MBSAQIP Registry was reviewed (2015–2017) for Roux-en-Y gastric bypass, sleeve gastrectomy, and revision surgery based on ST and nST status. Univariate, multivariate logistic regression, and propensity matching analyses were performed. Results: Of 477,670 cases, 26.8% were performed with ST. For ST patients 79.9% were female (versus 80.3% nST) and mean body mass index was 45.2 6 8 kg/m2 (versus 45.0 6 8.1 kg/m2 nST). Overall, 31.7% of patients underwent Roux-en-Y gastric bypass (versus 25.7% nST), 65.9% underwent sleeve gastrectomy (versus 71.6% nST), and 2.4% of patients had revision surgery (versus 2.7% nST). After matching, no difference in 30-day mortality was observed between groups. However, ST patients had higher incidence of deep vein thrombosis (P 5 .004), pulmonary embolism (P 5 .005), superficial surgical site infection (P , .0001), postoperative sepsis (P 5 .005), blood transfusions (P 5 .0307), nonoperative interventions (P 5 .004), 30-day readmission rates (P , .0001), and longer operative times (P , .0001), but lower 30-day reoperation rates (P 5 .0001). Conclusion: Overall, there was no difference observed in 30-day mortality between the ST and nST groups. However, despite lower 30-day reoperation rates, ST patients exhibited higher rates of postoperative deep vein thrombosis, pulmonary embolism, superficial surgical site infection, postoperative sepsis, blood transfusions, 30-day readmission rates, and longer operative times than nST patients. (Surg Obes Relat Dis 2020;-:1–7.) Ó 2020 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved. -; -; -

This study was presented, in part, at the 2019 American Society for Metabolic and Bariatric Surgery (ASMBS) Weekend, Chicago, IL.

* Correspondence: Abdelrahman Nimeri, M.D., Atrium Health Weight Management, Department of Surgery, Carolinas Medical Center, 2630 E. 7th St., Charlotte, NC, 28204. E-mail address: [email protected] (A. Nimeri).

https://doi.org/10.1016/j.soard.2020.01.019 1550-7289/Ó 2020 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

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Selwan D. Barbat et al. / Surgery for Obesity and Related Diseases - (2020) 1–7

Bariatric and metabolic surgery (BMS) has become increasingly more accepted as an appropriate treatment for obesity. Over the past decade, the morbidity and mortality associated with bariatric surgery has improved significantly with the introduction of minimally invasive approaches, fellowship training in bariatric surgery, program accreditation, and the introductions of bariatric surgery-specific data registries, such as the Metabolic and Bariatric Surgery Accreditation Quality Improvement Program (MBSAQIP) Data Registry [1–3]. With the growth in the number of centers performing BMS and the steep learning curve associated with laparoscopic BMS, there is an increased demand for fellowshiptrained bariatric surgeons. As of 2019, the Fellowship Council website listed 62 accredited bariatric programs, with 84 fellows being trained in North America annually [1] (an increase from 61 centers/77 fellows trained in 2015 [2]). In addition, the American Society for Metabolic and Bariatric Surgery has created educational and clinical requirements to certify successful completion of bariatric training [3]. However, there is no standard in the approach of teaching provided, and there are many variations in techniques for specific bariatric operations. Additionally, with the increased rate at which BMS is performed, more general surgery residency programs are involving residents in teaching BMS [4]. As more bariatric procedures are performed (with or without trainees) there is a focused and heightened awareness toward measures for quality improvement, as demonstrated by the development and implementation of the MBSAQIP Data Registry. Several studies have reviewed patient outcomes from cases performed with residents and/or fellows involved in both general surgical and BMS procedures. The results from these studies vary considerably and include a range of study types (retrospective, prospective, administrative, and clinical registry). For example, several studies report no significant differences in outcomes when cases are assisted by surgical trainees (ST) [5–7], while others report increased complications (surgical site infections [SSI], readmissions, length of stay, and renal failure) [2,8–12]. Specific to bariatric surgery, it should also be noted that not all procedures are treated equally. For example, revision surgery (RS) and Roux-en-Y gastric bypass (RYGB) are technically more demanding/complex procedures (with a steeper learning curve) than sleeve gastrectomy (SG) and adjustable gastric band procedures. This has led to varied conclusions in the literature addressing patient outcomes for cases with ST assisting with RYGB procedures compared with other BMS procedures [2,4–13]. The aim of this study was to use the BMS-specific MBSAQIP Data Registry to compare the impact on patient outcomes after laparoscopic RYBG, SG, or RS when cases were assisted by ST versus nonsurgical trainees (nST).

Methods Institutional assurances The Carolinas Medical Center institutional review board certified that retrospective analyses of public, anonymized data sets (including the MBSAQIP Data Registry) are deemed exempt from institutional review board review. Data source The MBSAQIP Data Registry is a prospectively collected database, which contains details of .100 variables, including patient demographic characteristics, preoperative patient information, operative interventions, and 30-day postoperative morbidity and mortality. For this study, data were accessed from the MBSAQIP participant use files from (2015–2017), allowing us to gather information from 791 academic and community MBSAQIP-accredited centers. Within the MBSAQIP data registry, the site employs numerous mechanisms to ensure data consistency/reliability [14]. To determine the impact of BMS outcomes for cases assisted by ST, the MBSAQIP Data Registry was queried for patients undergoing laparoscopic RYGB, SG, or RS. To compare complications associated with procedures in which an ST was present, if the assistant type was documented as a resident or Minimally Invasive Fellow, they were deemed ST cases. For comparison, the nST included patients for who the assistant types were listed as none, physician assistant/nurse practitioner/registered nurse first assist, weight loss surgeon attending, or other attending. Exclusion criteria included patients undergoing a miniloop gastric bypass, gastric-plication, adjustable gastric band, endoscopic therapy, “other” flag, emergency cases, handassisted cases, natural orifice transluminal endoscopic surgery flag, open procedure, intragastric balloon, or any other bariatric procedures aside from those mentioned herein. These exclusions were applied to assess the most common weight loss surgery procedures while excluding potential confounding variables within the database. Baseline demographic characteristics and clinical parameters Patient demographic characteristics and clinical characteristics were compared between ST and nST groups to include age, sex, body mass index, race, ethnicity, and comorbidities (gastroesophageal reflux, hyperlipidemia, hypertension, renal insufficiency, dialysis dependency, type 2 diabetes, smoking status, steroid use, obstructive sleep apnea [OSA], use of anticoagulants, chronic obstructive pulmonary disease and/or history of myocardial infarction [MI], pulmonary embolism [PE], deep vein thrombosis [DVT], and prior cardiac surgery).

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Intraoperative and postoperative outcomes were compared with the primary outcome being 30-day mortality. Secondary outcomes included postoperative morbidity, readmission, reoperation, intervention, and length of operation. Major complications were defined as cerebral vascular accident, MI, PE, 30-day reoperation, and 30-day intervention. Minor complications were defined as deep or superficial SSI, postoperative sepsis, and postoperative pneumonia. Statistical analysis Statistical analysis was performed using R Software (version 3.4, R Foundation for Statistical Computing, Vienna, Austria). Continuous variables were reported as mean 6 standard deviation. Categoric variables were reported as frequency and percentages. Univariate comparisons of continuous variables were analyzed using paired t test or Wilcoxon’s rank sum tests for parametric (matched) and nonparametric (unmatched) data, respectively. Categoric variables were analyzed using a X2 test. Covariate matching was performed for ST versus nST by nearest-neighbor matching algorithm using the MatchIt package. Matching was performed on patient demographic characteristics (age, body mass index, race) and co-morbid risk factors (gastroesophageal reflux, mobility status, hypertension requiring medication, cardiac conditions, hyperlipidemia, history of DVT, venous stasis, anticoagulation therapy, renal conditions, previous foregut surgery, diabetes requiring insulin, smoking status, functional independence, oxygen usage, OSA, and chronic steroid usage). To assure balance on the distance measure did not introduce additional covariate variability, we plotted the distributions of covariates between control and treatment groups as assessed by absolute mean differences between groups (Supplemental Fig. 1). A value of P , .05 was considered significant. Results After applying exclusion criteria, 477,670 laparoscopic BMS (RYGB, SG, or RS) were identified, the patient characteristics for which are described in Supplemental Table 1. Overall, 26.8% (127,767 patients) of laparoscopic BMS procedures were performed with ST, and 73.3% (349,903 patients) were performed with nST. Of patients in the ST group, 31.7% had RYGB (versus 25.7% [nST group]), 65.9% had a SG (versus 71.6% [nST group]), and 2.4% underwent RS (versus 2.7% [nST group]). Overall, when assessing co-morbidity profile, more patients in the ST group were smokers (8.7% versus 7.9% [nST]; P , .0001), and more patients in the ST group had a history of MI, DVT, PE, cardiac surgery, hyperlipidemia, therapeutic anticoagulation, preoperative dialysis, renal insufficiency, insulin-dependent diabetes, OSA, and chronic steroid use (Supplemental Table 1).

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To best compare 2 similar groups in relation to their demographic characteristics and co-morbidity profile, a covariate matching was performed in which 126,601 patients in each of the ST and nST groups was used. After analysis, excellent matching was achieved for patient demographic characteristics with age and preoperative co-morbidity profile no longer highly significantly different, with the exception of OSA, which was higher in patients in the nST versus ST group (40.7% and 39.9% respectively; P , .0001; Table 1). Of note, while significant differences in age (44.6 6 12.0 with ST versus 44.7 6 11.9 yr with nST; P 5 .04) and body mass index (45.2 6 8 with ST versus 45.3 6 8.2 kg/m2 with nST; P 5 .0006) were maintained between the groups, these differences were not considered clinically important. The data are visually represented using a Love plot that displays all the demographic variables and compares the absolute mean difference between the unmatched (red circles) and matched (green circles) groups (Supplemental Fig. 1). We next compared matched 30-day outcomes for patients in the ST and nST groups. Doing so revealed there was no difference in 30-day mortality between the 2 groups (Table 2). However, patients in the ST group exhibited higher rates of PE, superficial SSI, postoperative sepsis, blood transfusions, DVT, nonoperative interventions, and 30-day readmission rates (Table 2). Conversely, 30-day reoperation rates were significantly higher in matched patients in the nST group compared with the ST group (.8% versus .7%; P 5 .0001; Table 2). Finally, operative time was significantly longer for patients in the ST group (107.8 6 54.7 min) compared with the nST group (85.5 6 49.0 min; P , .0001). Subset analysis of matched data based on procedure performed Using matched data for patients undergoing a RYGB procedure revealed patients in the ST group had higher rates of superficial SSI, postoperative sepsis, 30-day readmission, and longer operative time compared with patients in the nST group (Table 3). Conversely, patients in the nST group had higher 30-day reoperation rates (Table 3). There was no difference in 30-day mortality between the 2 groups (Table 3). For patients undergoing SG, patients in the ST group had higher rates of PE, superficial SSI, postoperative sepsis, DVT, 30-day readmission, and 30-day nonoperative intervention compared with patients in the nST group (Table 4). There was no difference in 30-day mortality between the 2 groups (Table 4). Finally, for those patients undergoing RS, patients in the ST group had higher rates of blood transfusions within 72 hours, 30-day readmission, 30-day nonoperative intervention, and longer operative times than patients in the nST group. However, 30-day reoperation rates were higher in patients in the nST group than

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Selwan D. Barbat et al. / Surgery for Obesity and Related Diseases - (2020) 1–7 Table 1 Patient demographic characteristics after matching

Age Female, % BMI White, % Hispanic, % Smoker, % GERD, % History of MI, % History of DVT, % History of PE, % Cardiac surgery, % HTN on meds, % HLD, % Preoperative dialysis, % Renal insufficient On anticoagulation, % Insulin-dependent type 2 diabetes, % COPD, % OSA, % Steroids, %

nST n 5 126,602

ST n 5 126,602

P value

44.7 6 11.9 80.2 45.3 6 8.2 64.5 13.4 8.0 31.3 1.4 2.1 1.4 1.2 63.7 24.1 .4 .7 3.0 9.0 1.7 40.7 1.9

44.6 6 12.0 80.3 45.2 6 8.0 64.6 14.2 7.9 31.3 1.4 2.0 1.4 1.2 63.3 23.9 .5 .7 2.9 8.8 1.7 39.9 1.9

.04 .58 .001 ,.0001 ,.0001 .54 .95 1.00 .70 .81 .84 .11 .31 .63 .44 .60 .25 .96 ,.0001 .57

Q5

nST 5 nonsurgical trainees; ST 5 surgical trainees; BMI 5 body mass index; GERD 5 gastroesophageal reflux disease; MI 5 myocardial infarction; DVT 5 deep vein thrombosis; PE 5 pulmonary embolism; HTN 5 hypertension; HLD 5 hyperlipidemia; COPD 5 chronic obstructive pulmonary disease; OSA 5 obstructive sleep apnea.

the ST group (P 5 .03; Table 5). There was no difference in 30-day mortality between the 2 groups (Table 5).

(precursor to MBSAQIP) [2], or smaller data sets from the MBSAQIP registry [10,11], report patients undergoing RYGB or SG with ST present have higher co-morbidities and worse outcomes [2,10–12]. These data are supported by our analysis using the first 3 years of data available in the MBSAQIP database, which identified patients operated on with ST present are more likely to have a higher

Discussion Previous studies using the American College of Surgeons National Surgical Quality Improvement Program database

Table 2 Matched operative outcomes of patients undergoing RYGB, SG, and RS with ST and nST Major complications

nST n 5 126,602

ST n 5 126,602

P value

Pulmonary embolism, % Cerebrovascular disease, % Intraoperative cardiac arrest Postoperative myocardial infarct, % DVT requiring treatment, % 30-d reoperation, % 30-d nonoperative intervention, % Emergency reoperation, % 30-d mortality, % Minor complications Superficial SSI, % Deep SSI, % Postoperative sepsis, % Postoperative pneumonia, % Blood transfusion, % 30-d readmission, % Operative time, min

.1 .0 .0 .0 .2 .8 1.2 .0 .1

.1 .0 .0 .0 .2 .7 1.3 .0 .1

.005 .50 .15 .17 .004 .0001 .004 .0004 .84

.4 .1 .0 .2 .6 3.9 85.5 6 49.0

.6 .1 .1 .2 .7 4.2 107.8 6 54.7

,.0001 .94 .005 .66 .03 ,.0001 ,.0001

nST 5 nonsurgical trainees; ST 5 surgical trainees; DVT 5 deep vein thrombosis; SSI 5 surgical site infection.

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Table 3 Matched operative outcomes of patients undergoing laparoscopic RYGB with ST and nST Major complications

nST n 5 40,335

ST n 5 40,252

P value

Pulmonary embolism, % Cerebrovascular accident, % Intraoperative cardiac arrest Postoperative myocardial infarction, % DVT requiring treatment, % 30-d reoperation, % 30-d nonoperative intervention, % Emergency reoperation, % 30-d mortality, % Minor complications Superficial SSI, % Deep SSI, % Postoperative sepsis, % Postoperative pneumonia, % Blood transfusion, % 30-d readmission, % Operative time, min

.2 .0 .0 .0 .1 1.3 2.1 .0 .1

.2 .0 .1 .1 .2 1.1 2.1 .0 .1

.13 .45 .13 .16 .13 .005 .95 .02 1.00

.9 .2 .1 .3 1.0 5.5 114.2 6 54.9

1.1 .1 .2 .4 1.0 5.8 145.2 6 57.8

.0005 .94 .005 .80 .89 .04 ,.0001

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RYGB 5 Roux-en-Y gastric bypass; ST 5 surgical trainees; nST 5 nonsurgical trainees; DVT 5 deep vein thrombosis; SSI 5 surgical site infection.

longer operative times led to higher rates of all complications assessed, prolonged length of stay, and increased DVT risk [17]. Of note, this study also identified operative duration was longer for fellows than residents, probably as a result of increased involvement of fellows for critical portions of the case [17]. Similarly, Goldberg et al. [10] report that longer operative durations in RYGB and SG when performed by fellows led to higher postoperative complications but, when operative duration was adjusted for, differences in complications were no longer observed.

co-morbidity burden than patients treated when ST are not present. While our analysis demonstrates patients in the ST group had longer operation times and more complications than nST patients, patients treated with ST present had lower reoperation and similar mortality rates compared with the nST group, independent of the type of procedure (RYGB, SG, or RS) performed. One explanation for worse outcomes when ST are present may relate to operative duration [16]. Specific to BMS, an evaluation of the Michigan Bariatric Surgery Collaborative database for RYGB (2006–2012) reports

Table 4 Matched operative outcomes of patients undergoing laparoscopic SG with ST and nST Major complications

nST n 5 83,446

ST n 5 83,544

P value

Pulmonary embolism, % Cerebrovascular accident, % Intraoperative cardiac arrest Postoperative myocardial infarction, % DVT requiring treatment, % 30-d reoperation, % 30-d nonoperative intervention, % Emergency reoperation, % 30-d mortality, % Minor complications Superficial SSI, % Deep SSI, % Postoperative sepsis, % Postoperative pneumonia, % Blood transfusion, % 30-day readmission, % Operative time, min

.0 .0 .0 .0 .1 .5 .8 .0 .1

.1 .0 .0 .0 .2 .5 .9 .0 .1

.01 .25 .34 .43 .02 .06 .001 .08 .54

.2 .0 .0 .1 .4 3.0 70.4 6 37.2

.3 .0 .1 .1 .4 3.2 88.63 6 39.8

.004 .41 .04 .15 .09 .002 ,.0001

SG 5 sleeve gastrectomy; ST 5 surgical trainees; nST 5 nonsurgical trainees; DVT 5 deep vein thrombosis; SSI 5 surgical site infection.

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Selwan D. Barbat et al. / Surgery for Obesity and Related Diseases - (2020) 1–7 Table 5 Matched operative outcomes of patients undergoing laparoscopic RS with ST and nST Major complications

nST n 5 2821

ST n 5 2806

P value

Pulmonary embolism, % Cerebrovascular accident, % Intraoperative cardiac arrest Postoperative myocardial infarction, % DVT requiring treatment, % 30-d reoperation, % 30-d nonoperative intervention, % Emergency reoperation, % 30-d mortality, % Minor complications Superficial SSI, % Deep SSI, % Postoperative sepsis, % Postoperative pneumonia, % Blood transfusion, % 30-d readmission, % Operative time, min

.2 .0 .2 .1 .2 3.2 2.4 .0 .3

.2 .0 .1 .0 .3 2.3 3.8 .0 .2

1.00 1.00 .73 1.00 .57 .03 .002 .03 .78

1.0 .4 .9 .7 1.2 7.0 118.4 6 65.3

1.3 .6 .8 .9 2.6 8.8 142.8 6 87.7

.38 .38 .57 .36 .0003 .01 ,.0001

RS 5 revision surgery; ST 5 surgical trainees; nST 5 nonsurgical trainees; DVT 5 deep vein thrombosis; SSI 5 surgical site infection.

Level of experience during training and when during the fellowship training procedures are performed, identifies increased incidence of complications during the initial period of bariatric fellowship training [12]. However, the authors note the negative impact of fellow participation on complication rate after RYGB and SG procedures is no longer detectable when adjusting for operative duration [12], and the higher risk of morbidity reported in the first half of the academic year was abrogated by the second half of the academic year. These reports, when taken with our findings, suggest the opportunity exists for training programs to evaluate and optimize operating room time for BMS procedures when assisted by ST to improve outcomes during their initial training period. To our knowledge, this is the first MBSAQIP analysis comparing outcomes of RS with and without ST. As with RYGB and SG, the majority of RS were performed without ST present. When ST were present, patients had higher rates of blood transfusion (within 72 hr), 30-day readmission, 30-day nonoperative intervention, and longer operating room duration, but lower 30-day reoperation rates, and no difference in 30-day mortality. In comparison, an Australian study evaluated 82 patients with planned band-to-bypass procedures, of which 28 cases had fellows as the primary operator. Overall, this study reported a 7.3% complication rate, but there were no differences in complication rates when comparing fellows with nontrainees performing the procedure [13]. While this disparity to our findings may be accounted for by the relative difference in patient population sizes, it is also important to note a variety of procedures in BMS may be considered “revision surgery,” details of which are not provided within the MBSAQIP database, making it

difficult to decipher, which procedures may be considered higher risk for ST compared with experienced surgeons. In addition to short-term postoperative complications, we also identified lower 30-day reoperation and 30-day nonoperative reintervention rates in the ST group, especially for patients undergoing RYGB or RS. One explanation for these findings may be the increased availability of trainees present in a teaching hospital to perform postoperative evaluations and (based on their relative inexperience) a lower threshold to admit patients postoperatively that results in earlier recognition of postoperative issues that consequently decrease the need for subsequent operative intervention. While understanding these differences may be possible using smaller, pair-matched patient populations, this is not currently possible within the MBSAQIP data registry. Although our study identifies increased complications in BMS when ST are present, it is important these findings be considered alongside clinical relevance. For instance, although the risk of DVT is higher for patients in the ST group (.3%) compared with patients in the nST group (.2%), the overall rate of DVT for both groups is within the lower end of the documented range of DVT rates (.3%–3%) [18]. Equally, the MBSAQIP database does not allow us to determine pre- and postoperative DVT prophylaxis regimens (including extended DVT prophylaxis). Thus, while our findings suggest the differences we report for DVT should be considered sufficient for bariatric surgeons to take note, especially regarding operative time and potential discrepancies in DVT prophylaxis, these rates should be considered within the broader spectrum of reported incidence rates for BMS and other common elective surgical procedures.

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While the data we present benefit from using the large data sets available within the bariatric-specific MBSAQIP data registry, our study is not without limitations. Of particular note, the MBSAQIP data registry only captures the frequency of ST participation in the case but not the details of the component(s) of the procedure they performed, if .1 ST was present (and if so, the specific role of each ST). The MBSAQIP database also only includes short-term (30-d) outcomes, meaning the potential impact of ST versus nST involvement on long-term outcomes is unknown. Equally, the MBSAQIP database does not allow us to differentiate high- from low-volume centers, and previous studies report high-volume centers have lower complication rates than low-volume centers [19]. Finally, we assume the presence of a ST in a BMS case may contribute to increased risk of complications. However, institutions with surgical residents and minimally invasive fellows are also likely to have trainees in other disciplines that may also be involved in perioperative patient care, a factor not accounted for in the MBSAQIP data registry. Conclusions When considering the patient population undergoing BMS, the majority of primary and revision BMS in the United States are performed in the absence of ST. In our analyses, ST assistance was associated with slightly (but significantly) higher co-morbidity burden, albeit with lower 30-day reoperation rates and no difference in 30-day mortality. However, it is important to note the relatively low complication rates of laparoscopic BMS (compared with other elective surgical procedures) within the perspective of the large data sets analyzed when interpreting these findings. When doing so, we contend our data support the safety of ST assisting in BMS procedures under close supervision as they develop their knowledge and skills. Disclosures

Q10

Abdelrahman Nimeri is a speaker for Medtronic. The other authors do not have any disclosures to report. Supplementary materials Supplementary material associated with this article can be found, in the online version, at https://doi.org/10.1016/ j.soard.2020.01.019. References [1] Directory of Fellowships [homepage on the Internet]. Los Angeles: The Fellowship Council; c2020 [cited 2019 Apr 5]. Available from: https://fellowshipcouncil.org/directory-of-fellowships/.

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