Laparoscopic sleeve gastrectomy (LSG) is the most common bariatric procedure performed in the United States [1, 2]. Although LSG may be considered less technically challenging than gastric bypass, there remains considerable variation regarding the technical aspects of the operation [3,4,5,6]. Understanding the effect of operative technique on clinical outcomes is vital to improving quality and determining best practices. Thus far, recommendations regarding specific LSG techniques have been conflicting and it is unclear whether standardization will have an impact on outcomes.

There are several challenges to identifying best practices for operative technique in bariatric surgery. First, defining “optimal outcomes” depends on which outcome measure is being studied and can range from complication rates (i.e. “safety”) to weight loss (i.e. “efficacy”). Moreover, it is unclear if these two outcome measures correlate. Second, gathering objective data on the technical aspects of a surgical procedure can be challenging. Utilizing operative notes alone may be inaccurate, biased, or lack the technical nuances that make each procedure unique, despite their likeness on paper. Finally, correlating specific technical aspects of LSG to a single measure (i.e., leak) fails identify common practices employed by the top performing surgeons nor does it take into account surgeon experience, case volume or level of intraoperative assistance.

In this study, we aim to correlate operative technique with clinical outcomes for LSG by using surgical videos in conjunction with a statewide bariatric specific data registry. Technique-specific variables are compared between surgeons ranked in the top and bottom quartile for 30-day surgical complication rates and 1-year patient reported weight loss.

Methods

Study population

This study included surgeons who participate in the Michigan Bariatric Surgery Collaborative (MBSC), a statewide consortium that includes 38 surgical programs and 70 surgeons. Participating programs submit bariatric specific data to a clinical data registry (> 70,000 cases to date) and participate in quality improvement initiatives as well as tri-annual meetings. Data are abstracted by centrally trained abstractors using standardized definitions. Each participating hospital is also visited annually by external auditors to verify the accuracy and completeness of the submitted data. For this study, 30 surgeons (43%) submitted a representative video of a laparoscopic sleeve gastrectomy with all patient identifiers removed prior to submission. Video collection occurred between 2015 and 2016. The study was approved by the institutional review board of the University of Michigan for the MBSC and surgeons signed consent prior to participation.

Study design and data collected

This is an observational study evaluating operative technique of top performing surgeons using surgical videos and risk-adjusted surgeon-specific 30-day and 1-year outcomes. Participating surgeons provided information about their age, number of years performing bariatric surgery, completion of a bariatric surgery fellowship and the MBSC registry was queried to obtain data on type of surgical practice (teaching vs non-teaching hospital), surgical volume, and mean operative time for LSG. Videos were reviewed by a single surgeon (OAV) who was blinded to the surgeon performing the procedure. Technique-specific data obtained from the video included stapler vendor (Covidien, Mansfield, MA, USA and Ethicon Endo-Surgery., Cincinnati, OH, USA), number of stapler loads used to perform the LSG, use of buttressing, oversewing of the staple line, imbrication of the staple line, location of oversewing/imbricating, omentoplasty, use of fibrin sealant, intraoperative endoscopy, and use of drains. Additional information including type of assistant (i.e., surgical resident, nurse practitioner, physician assistant or surgical scrub), bougie size, and use of postoperative imaging studies were obtained via surgeon surveys.

Aggregate data from participating surgeons on 7023 sleeve gastrectomy cases were obtained from the MBSC registry during the study period (2015–2016). Data included patient characteristics, 30-day and 1-year excess body weight loss. Baseline patient characteristics included age, body mass index (BMI), gender, race, and comorbid conditions including diabetes, hyperlipidemia, hypertension, gastroesophageal reflux disease (GERD), and obstructive sleep apnea (OSA). Postoperative outcomes included 30-day surgical complication rate, which included rates of leak, hemorrhage, infection, obstruction, and reoperation. Data on excess body weight loss at 1 year were available for 3630 patients.

Analysis

We calculated risk-adjusted rates of surgical complications and %EBWL at 1-year following surgery for each surgeon, using multivariate logistic regression models for complications and a multivariate linear regression model for excess body weight loss with robust standard errors to account for clustering. Risk-adjusted rates were then calculated as the ratio of total number of observed to expected number of outcomes for each surgeon (observed-to-expected ratio) multiplied by the overall average rate of specific outcome (leak, hemorrhage, infection, obstruction, and reoperation).

We ranked the surgeons for safety using risk-adjusted outcomes of surgical complications and for efficacy using %EBWL. Individual surgeon rankings range from 1 to 30 with the lowest to highest surgical complication rates and EBWL% from highest to lowest. We looked at the correlation between surgeon safety and efficacy ranking by using Pearson correlation coefficient. Surgeons were also categorized into individual quartiles for performance based on individual measures of surgical complication rates (leak, hemorrhage, infection, obstruction, and reoperation), respectively.

We compared surgeon characteristics and technique-specific variables between top and bottom quartiles of performance using Chi square and Wilcoxon rank sum tests as appropriate. For all the specific risk-adjusted outcomes, we used logistic regression models with forward stepwise selection using p < 0.1 as inclusion criteria to select other covariates (comorbidities) in addition to age, gender and BMI. All reported p values were 2-sided and a value of < 0.05 was used as threshold for significance. All statistical analyses were performed using SAS version 9.4.

Results

Patient characteristics among surgeons participating in the study are presented in Table 1. Mean age was 45.4 years and mean BMI was 47.5 kg/m2. Surgeon rankings are presented in Fig. 1. There was no correlation between rankings for safety and efficacy (Pearson correlation coefficient, 0.063; p = 0.741). Surgeons ranked in the top quartile for safety had a significantly lower mean overall surgical complication rate (0.96% vs. 3.61%, p < 0.0001) when compared with surgeons in the bottom quartile. (Table 2). Likewise, surgeons ranked in the top quartile for efficacy had a higher mean overall EBWL% (63.0% vs. 52.0%, p = 0.0002). The safest and most effective surgeons also had faster mean operative times (74 min vs. 82 min, p < 0.0001 and 79 min vs 89 min p < 0.0001, respectively). However, the remaining characteristics between surgeons in the top and bottom quartiles were not significantly different (Table 3).

Table 1 Patient characteristics among participating surgeons
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Fig. 1
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Surgeon rankings for safety and efficacy. Pearson correlation coefficient, 0.063; p = 0.741

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Table 2 Comparison of risk adjusted 30-day complication rates and risk adjusted 1-year patient reported weight loss among surgeons who were ranked in the top and bottom quartiles for both safety and efficacy
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Table 3 Comparison of surgeon specific characteristics among surgeons who were ranked in the top and bottom quartiles for safety and efficacy
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Participating surgeons demonstrated a wide variety of operative techniques when performing laparoscopic sleeve gastrectomy (Fig. 2; Table 4). The number of ports ranged from 3 to 6 and bougie size ranged from 30 to 42 Fr. The number of stapler loads utilized also varied from 4 to 7. Buttressing material was utilized in 62.1% of cases and surgeons either oversewed or imbricated the staple line in 13.8% and 24.1% of cases, respectively. Location of oversewing/Imbricating also varied, as did use of fibrin sealant and intraoperative endoscopy. Drain placement (6.9%) and use of postoperative imaging studies (13.8%) was uncommon. Evaluation of technique-specific variables among surgeons in the top and bottom quartile for each individual outcome measure is presented in Table 4. Surgeons in the bottom quartile for leak had a significantly higher mean leak rate when compared to surgeons in the top quartile (1.20% vs. 0%, p = 0.0072) and were more likely to use buttressing material (85.7% vs. 40.0%, p = 0.032). Surgeons with higher leak rates also trended to using smaller bougie sizes (34 Fr vs. 36 Fr, p = 0.054). Otherwise, there were no unique technical findings among top and bottom quartiles of surgeons.

Fig. 2
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Operative technique for laparoscopic sleeve gastrectomy among participants in the study. (Color figure online)

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Table 4 Comparison of technique-specific variables among surgeons who were ranked in the top and bottom quartiles for specific measures of safety and efficacy
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Discussion

This is the first study to use surgical videos along with a statewide bariatric-specific data registry to evaluate operative technique for laparoscopic sleeve gastrectomy. Using the MBSC collaborative quality improvement paradigm, surgeons were ranked based on risk-adjusted outcomes and outliers were compared with respect to surgeon and technique-specific variables. Interestingly, we found that rankings of surgeons based on surgical complication rates did not correlate with that of weight loss, which means that “optimal” outcomes depends on how it is defined and is not limited to the same group of surgeons. In addition, we found no correlation among surgeons in the top and bottom quartiles for safety and efficacy with respect to annual or total case volume, fellowship training, or number of years practicing bariatric surgery. Although top performing surgeons had faster operative times, there was no unique pattern of techniques to distinguish surgeons in the top and bottom quartiles for weight loss, hemorrhage infection, obstruction, or reoperation. We did find that the use of buttressing and smaller bougie sizes was more common among surgeons with higher leak rates, however, the overall rate was extremely low, which suggests that some degree of technical variation is acceptable among a group of practicing surgeons participating in a collaborative quality improvement program.

Prior studies evaluating the impact of surgical techniques on safety outcomes for LSG focused on specific adverse events including staple line leak and hemorrhage. Larger bougie sizes (> 40 Fr) has been advocated Aurora et al., while D’Ugo, Gagner and Gill each have recommended the use of staple line reinforcement, although the specific type of reinforcement has varied (i.e., bovine pericardium, oversewing, thrombin matrix, or absorbable polymer) [7,8,9,10]. In a prior study published by the MBSC, oversewing was noted to be associated with fewer leaks; however, specific sewing techniques varied and the overall rate of leaks decreased during the study period of 5 years [11]. Interestingly, the use of buttressing was not predictive of leaks in our prior study, which spanned from 2007 to 2013 and may represent a change in the use of buttressing over time as the present study took place between 2015 and 2016. In fact, our findings are more consistent with a recent report by Berger et al., who analyzed data from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) registry to assess the impact of a surgical techniques on a variety of outcome measures [4]. Their overall morbidity (4.34%), leak rate (0.9%), and bleeding rate (0.82%) was low and similar to our study. They found that bougie sizes ≥ 38 Fr was associated with lower leak rates and also found that buttressing ± oversewing was associated with increased leak rates.

Efforts toward standardization of LSG technique have been attempted in the past but lacked an evidence-based approach. In 2011, an international panel of expert bariatric surgeons who had performed a high volume of cases (> 500) was queried on specific technical considerations for LSG [5]. At the time, they recommended bougie sizes between 32 and 36 Fr and also recommended the use of staple line reinforcement to reduce bleeding along the staple line. In 2014, the survey was repeated and compared with the 2011 panel as well as survey data obtained from a general surgeon audience [12] This study highlighted areas of technical variation between experts and the general bariatric surgeon including the use of larger bougie sizes among experts (median size being 36 Fr) as well as the use of buttressing material along the staple line. They noted that both experts and general bariatric surgeons oversewed the staple line and that there has been a movement toward using the appropriate staple height for the various thicknesses of the stomach. In our study, we identified expert surgeons by ranking them based on their outcomes for safety and efficacy and not simply case volume. Interestingly, when comparing surgeons in the top and bottom quartile for safety and efficacy, we found no difference in total and annual LSG volume, surgeon age, years in bariatric practice, fellowship training or if they were in private practice or at a teaching hospital. Interestingly, we did find that smaller bougie sizes and use of buttressing material was more common among surgeons with higher leak rates, which is consistent with that of the expert panel noted above. Nevertheless, we found that technical variation exists among surgeons in the MBSC and that surgeons with the best weight loss outcomes are not necessarily similar to those with the lowest surgical complications. Also, it is possible that certain techniques may improve one outcome measure, while worsening another. For instance, buttressing material was more commonly used among surgeons with higher leak rates but also among surgeons with lower hemorrhage rates (although not statistically significant). Thus, technical recommendations for standardization must be considered in the context of the outcomes being measured.

Prior studies have also evaluated more nuanced technical variables for LSG. For example, Bellanger et al., recommended minimizing the risk of creating strictures at the incisura angularis and stapling near the esophagus at the angle of His in a report evaluating 529 consecutive LSG cases without a leak [13]. With regard to stapling, Huang et al., argued that leaks can be avoided by calibrating the appropriate staple height with that of the tissue thickness in a study evaluating the range of gastric thickness in three areas of stapling during LSG [14]. We noted a high variability in staple heights as well as use of buttressing in our study. This may indicate that surgeons are making intraoperative decisions about staple height based on their best judgement of tissue thickness, despite a lack of objective evidence. Location of first staple load as measured from the pylorus has also been reported by Berger et al. [4]. They found that the distance had no impact on leaks or bleeding events but showed an increase in weight loss with increasing distance from the pylorus. Although we are capable of capturing such data from surgical videos, we recognize that measurements of distance, tissue thickness, and sleeve size may be subject to biases in perception if not measured objectively. Future studies evaluating these measures are forthcoming and will involve peer review of videos.

We recognize that there are several limitations to our study. First, not all surgeons in the MBSC participated with only 43% submitting a video. As a result, clinical outcomes and operative technique of other top performing surgeons may not be represented. Nevertheless, this study involves the largest number of sleeve gastrectomy videos reviewed for the purposes of assessing the impact of operative technique on outcomes. Furthermore, surgical complication rates and weight-loss among surgeons participating in the study are consistent with those reported in the literature, indicating that our study sample may be comparable to others. Second, 1-year weight loss data were only available for 52% of eligible patients and this may have biased weight loss results. However, perioperative 30-day outcomes were obtained on all patients in the study and case volumes between surgeons in the top and quartile were similar. Moreover, risk-adjusted outcomes were utilized when performing the analysis. We also recognize that a single video may not be representative of a surgeon’s entire surgical repertoire and it may be possible that a surgeon’s technique has evolved over time. For this reason, we decided only to evaluate outcomes during the study period in which the videos were collected (2015–2016). Finally, this study does not take into account variations in surgical skill, which represents how well a surgeon executed the various steps of the LSG procedure. In a prior study of patients undergoing laparoscopic Roux-en Y gastric bypass, Birkmeyer et al., identified a significant association between surgical skill and outcomes [15]. Our study found that mean operative times among top performing surgeons were significantly lower, indicating that there may be additional measures of technical quality that may be captured from surgical videos. Future studies involving peer review of videos assessing measures of surgical skill are currently being conducted.

Conclusion

Technical variation for laparoscopic sleeve gastrectomy exists among surgeons participating in a state-wide quality collaborative and appears to have minimal effect on outcomes. Top performing surgeons did have faster operative times; however, surgeon rankings of safety did not correlate with that efficacy. Further analysis of surgical videos may provide additional insight on novel measures that relate technical quality with optimal outcomes.