Safety of Single Stage Revision Laparoscopic Sleeve Gastrectomy Compared to Laparoscopic Roux-Y Gastric Bypass after Failed Gastric Banding

Background Reoperation, after failed gastric banding, is a controversial topic. A common approach is band removal with conversion to laparoscopic Roux-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG) in a single-step procedure. Objective This study aimed to assess the safety of revisional surgery to LSG compared to LRYGB after failed laparoscopic adjustable gastric banding (LAGB) based on MBSAQIP Participant User File from 2015 to 2018. Methods Patients who underwent a one-stage conversion of LAGB to LSG (Conv-LSG) or LRYGB (Conv-LRYGB) were identified in the MBSAQIP PUF from 2015 to 2017. Conv-LRYGB cases were matched (1:1) with Conv-LSG patients using propensity scoring to control for potential confounding. The primary outcome was all-cause mortality. Results A total of 9974 patients (4987 matched pairs) were included in the study. Conv-LRYGB, as compared with conv-SG, was associated with a similar risk of mortality (0.02% vs. 0.06%; relative risk [RR], 0.33; 95% confidence interval [CI], 0.03 to 3.20, p = 0.32). Conversion to LRYGB increased the risk for readmission (6.16% vs. 3.77%; RR, 1.63; 95%CI, 1.37 to 1.94, p < 0.01); reoperation (2.15% vs. 1.36%; RR, 1.57; 95%CI, 1.17 to 2.12, p = <0.01); leak (1.76% vs. 1.02%; RR, 1.57; 95%CI, 1.72 to 2.42, p < 0.01); and bleeding (1.66% vs. 1.00%; RR, 1.66; 95%CI, 1.7 to 2.34, p < 0.01). Conclusions The study shows that single-stage LRYGB and LSG as revisional surgery after gastric banding, are safe in the 30-day observation with an acceptable complication rate and low mortality. However, conversion to LRYGB increased the risk of perioperative complications.


Introduction
Laparoscopic adjustable gastric banding (LAGB) was a popular bariatric procedure in the late 1990s and early 2000s [1] However, studies with long-term follow-up revealed poor weight loss outcomes and serious complications, including band erosion, slippage, and gastric pouch enlargement. [2] The majority of patients after LAGB required band removal or conversion to another bariatric procedure due to weight regain and complications. [3][4][5][6][7] Reoperation, after failed gastric banding, is a controversial topic. Band removal with conversion to gastric bypass or sleeve gastrectomy in a single-step procedure is one treatment option. In the analysis of MBSAQIP Participant User File (PUF) from 2015 revealed that conversion to sleeve gastrectomy might be a safer approach than gastric bypass surgery. [8] The observation was surprising because most surgeons advocate conversion to gastric bypass. We decided to replicate the study utilizing MBSAQIP data from 2015 to 2018 and addressing critical methodological flaws.
This study aimed to assess the safety of revisional surgery to laparoscopic sleeve gastrectomy (LSG) compared to laparoscopic Roux-Y gastric bypass (LRYGB) after failed laparoscopic adjustable gastric banding (LAGB) based on MBSAQIP Participant User File from 2015 to 2018.

Study Design
This study was a retrospective registry-based analysis of patients who underwent a one-stage conversion of LAGB to LSG (Conv-LSG) or LRYGB (Conv-LRYGB). All surgeries were performed between January 1, 2015, and December 31, 2018, at centers participating in the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP). The MBSAQIP prospectively collects data on many variables, including standardized demographics, preoperative comorbidities, laboratory values, and 30-day postoperative mortality and morbidity outcomes for patients undergoing bariatric treatment in participating hospitals in the United States and Canada. [9] The definitions of variables are available in the official MBSAQIP manual. [10] Study Population -Strategy Selection Figure 1 shows the Strategy for Case Selection. Data analysis was performed using current recommendations and checklists for large surgical datasets. [11][12][13] In the first step, we identify all cases of patients who underwent sleeve gastrectomy or Roux-en-Y gastric bypass (as indicated by the use of 43,775 or 43,644 as the principal current procedural terminology [CPT] code for surgery type, according to the MBSAQIP PUF manual). In the next steps, we excluded cases whose initial surgical approach was listed as other than laparoscopic conventional. Other exclusions were: American Society of Anesthesiologists (ASA) class of 5 or missing, cases with additional unlisted CPT codes (for Miniloop Gastric Bypass, Gastric Plication, Endoscopic Therapy, Other, Intragastric Baloon), emergency cases, conditions present at the time of surgery, lack of 30-day follow-up, and BMI below 30 or over 100 kg/m2.
Additional validation & quality tests were performed on two cohorts to remove cases with the following criteria from the PUF 2015, PUF 2016, PUF 2017, and PUF 2018 datasets.
• Records with incomplete data regarding the highest and closest BMI before or after surgery.
• BMI variation of more than ten units between two subsequent postoperative appointments.
• [only LSG patients] Reported bougie size below 30 or over 60 French. Bougie size range described in the literature is between 30 and 60 French. [14] • [only LSG patients] Reported distance from pylorus exceeding 9 cm. Distance >10 cm was not described in the literature. [15] Observations with missing data were excluded from the analysis.
Finally, all observations with at least one code for AGB removal [43,774, 43,772] listed as "Other CPT" or Concurrent CPT codes" were identified as cases of adjustable gastric band removal (AGB) with one stage conversion to Laparoscopic Sleeve Gastrectomy (Conv-LSG) or Laparoscopic Roux-Y Gastric Bypass (Conv-LRYGB). Conv-LRYGB cases were matched (1:1) with Conv-LSG patients using propensity scoring to control for potential confounding.

Outcomes
The primary outcome of the study was all-cause mortality. Secondary outcomes included: • Operative time (OR).
• Length of hospital stay (LoS).
• Including unplanned admission rate to the Intensive Care Unit within 30 days, pulmonary embolism, space surgical site infections, progressive renal insufficiency, postoperative sepsis, unplanned intubation, postoperative urinary tract infections, vein thrombosis requiring therapy, acute renal failure, postoperative cardiac arrest requiring CPR, coma over 24 h, stroke or cerebrovascular accident, postoperative deep incisional surgical site infections, postoperative myocardial infarction, postoperative ventilation, intraoperative nerve injury, pneumonia, postoperative septic shock, unplanned intubation, Clostridium difficile infection, and wound disruption.

Statistical Analysis
Propensity scoring was used to minimize selection bias. The matching procedure was based on the probability of having conversion to LRYGB. Cases were matched with controls by 18 variables. The matching was done using a 1:1 greedy-  1 Flow chart of the study matching algorithm, with a caliper of 0.05 standard deviation of the logit of the propensity score. [16] We assessed standardized differences for all the baseline covariates after matching to check the postmatch balance. Standardized differences below 0.1 for a given covariate indicate a small imbalance. In the matched cohort, continuous outcomes were analyzed using the paired t-test or Wilcoxon signed ranks test. Dichotomous outcomes analyzed using McNemar's analysis or Cochran-Mantel-Haenszel test. A description of effect estimates (risk ratio, RR) and 95% confidence interval (95% CI) was reported for category outcomes. The mean difference (or median) with 95% CI was reported for continuous variables. The analysis was performed using SAS® software, University Edition (SAS 9.4 Institute Inc., Cary, NC, USA).

Results
A total of 14,235 cases were used in propensity score matching ( Fig. 1). Table 1 presents the baseline characteristics of analyzed patients. Patients who were converted to LRYGB were more likely to have diabetes, sleep apnea, hypertension, hyperlipidemia, GERD, and had higher BMI. After matching, 4987 pairs were included in the final analysis. The C-statistic for the model was 0.604. The standardized differences were < 0.1 for all variables, indicating a lack of significant differences between the two groups. ( Table 2).

Outcomes of Interest
The results are presented in Table 3

Discussion
After a decade of popularity, adjustable gastric banding almost vanished. The reasons were poor weight loss outcomes and late severe complications, including band erosion, slippage, and gastric pouch enlargement. [2] Revision of failed gastric banding has become a common practice. [3][4][5][6][7] Choosing the next bariatric procedure is a controversial topic. Conversion to Roux-en Y gastric bypass and sleeve gastrectomy is the most common. It can be done concomitantly or as a two-stage procedure. The single-stage approach has a significant advantage -require fewer total surgeries. Thus, it is recognized as less demanding for patients. However, it is demanding for a surgeon, who needs to take down the band and fibrosis capsule before proceeding with the next step. Moreover, firing staples through the band related gastric inflammation does not seem to be the best idea. The metaanalysis by Zadeh at el. revealed that a one-stage approach was favored in the Roux-en-Y subgroup, but two-stage conversions appeared to have a lower risk of a leak in the sleeve gastrectomy subgroup. [17] The difference was explained by the involvement of different anatomy regions in each surgery. In conversion to Roux-Y gastric bypass, a pouch creation and gastro-jejunal anastomosis can be done above the band's place. In sleeve gastrectomy, the portion of the stomach compressed by the gastric band is usually transected by the stapler. The two-stage approach gives the time needed to resolve the inflammation and thus reduces the staple line leak risk. For this reason, surgeons are afraid of doing a conversion to LSG as a single-stage procedure.
The analysis of MBSAQIP data from 2015 was the first study showing the opposite. Surprisingly, the single-stage conversion of failed gastric banding was associated with more significant morbidity and higher complication rates when converted to LRYGB versus LSG. These differences were notable regarding bleeding events, 30-day reoperation, 30-day readmission, operative time, and hospital stay. [8] The conclusion was far from popular belief. Despite the utilization of a sizeable medical registry, the analysis did not achieve sufficient power to detect a significant leak rate.
We decided to replicate the study utilizing MBSAQIP data from 2015 to 2018 and addressing critical methodological flaws. Several issues make the present analysis unique. First, using datasets from 2015 to 2018, we obtained a large sample size. This sample size improved the power of our analysis significantly and was sufficient to detect meaningful differences. Second, Noyes et al. and Papasavas et al. stated various data quality issues in MBSAQIP datasets. [18,19] For this reason, we improved the strategy for the study population selection and performed additional quality checks. Third, we applied propensity score matching using the greedy algorithm. The algorithm has an important featureit does not assign the same control subjects for different cases. At present, this method guarantees the best possible matched set. We also decided to investigate the magnitude of effect size than interpret null-hypothesis significance testing. [20] Lastly, we analyzed the most likely reasons for readmission and reoperation, which shed more light on this challenging topic. The presented analysis revealed that conversion to LRYGB did not increase the risk of 30-day death. The tendency was opposite but not statistically significant. The most likely reason for death was stated as "Other" for all cases. Overall, the conversion of failed gastric banding to either LRYGB or LSG was safe with acceptable low mortality.
Our study supported previous observations. First, the single-stage conversion is safe, and the overall mortality is very low. Second, the one-stage revision sleeve gastrectomy compared to a one-stage Roux-Y gastric bypass after failed gastric banding had a better safety profile in the short term. Our study is the first showing a higher risk for an anastomotic leak, 30-day intervention, and emergency department visits in the group converted to LRYGB. The need for conversion to open in our study was low. The analysis of most likely reasons for reoperation showed that each procedure has its profile of complication. In the group of patients after conversion to LRYGB, most reoperations were due to intestinal obstruction, whereas in Conv-LSG, the most common reason was a staple line leak.
It is essential to highlight that although conversion LAGB to LRYGB increased from 57% to 141% reoperation rate, it does not increase the overall mortality. A possible reason is a fact that complications after LRYGB are easier manageable. Small bowel obstruction (SBO) after LRYGB is commonly reported in the literature. Internal hernia and adhesions are responsible for most cases for SBO. Operative treatment remains the definitive standard and should not be delayed. [21] On the other hand, staple line after sleeve gastrectomy is challenging to manage. The occurrence of this complication  [23] It is much more than the median time reported for leaks after gastric bypass surgery, 13 days. [24] Likely, the 30-day observation period stated in the MBSAQIP can not capture the outcome in the cases where the leak after conversion to LSG was present regarding reoperation, intervention, and death. Even though the leak was the most likely reason for reoperation in the Conv-LSG group, the incidence was lower than in Conv-LRYGB patients. In our analysis, laparoscopic sleeve gastrectomy after gastric banding showed a leakage rate of 1.02%, which was higher than reported from primary LSG in the MBASQIP databaseranging from 0.6 to 0.9%. [15,25] In our study, patients converted to LRYGB had an anastomotic leakage percentage of 1.76%. It corresponded to the analysis from 2015 and was higher than the reported rate for primary LRYGB in MBSAQIP analysis (0.6%). [26] Our study showed that conv-LRYGB increased the risk of short term complications in comparison to conv-LSG  The medical specialty of the physician performing the principal operative procedure (bariatric surgeon) 0.011 significantly. However, the effect size was mainly moderate, and it is difficult to determine if both procedures are comparable in terms of long-term complications because there is not enough data.
What is more, reports are indicating the significant benefit of conversion to LRYGB. The recent meta-analysis showed that conversion to LRYGB was associated with better weight loss at 12 and 24 months compared to conversion to LSG. [27] Our study's essential message is the following: both conversions of failed gastric banding have an excellent safety profile with acceptable complications rate. Although conversion to Laparoscopic Roux-Y gastric bypass increased the risk for short-term complications, the effect size is moderate. In this situation, the risk profile should not outweigh the weight loss benefits.
Our study has a few significant limitations. First, the MBSAQIP database is observational. The association between adverse events should be tested prospectively in a controlled environment to evaluate a potential causal relationship. However, considering the low rate of adverse events, it would be challenging to conduct a randomized control study with enough power to show a difference. Second, we could not assess the efficacy of conversions because of the lack of data on weight loss outcomes and comorbidities improvement. MBSAQIP database does not provide sufficient data on significant intraoperative variations in techniques. For this reason, we were not able to assess some essential technical details. Similarly, significant factors that could affect risk profile, such as operative findings and indications, were also not included.

Conclusion
Our study shows that single-stage laparoscopic Roux-Y gastric bypass and laparoscopic sleeve gastrectomy as revisional  surgery after gastric banding, are safe in the 30-day observation with an acceptable complication rate and low mortality. The conversion to LRYGB is more demanding and increases the risk of leak rate, bleeding events, reoperation, intervention, readmission, longer operative time and more extended hospital stay, emergency department visits, and morbidity. However, the effect size for the increase in risk was moderate.
The essential message is that increase in complications rate did not result in higher mortality. The decision about the type of procedure should be based on individual patient's risksbenefits assessment.

Compliance with Ethical Standards
Conflict of Interest The authors declare that they have no conflict of interest.
Ethical Statement All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Consent Statement
For this type of study consent was not required.
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