Surgical Strategies for the Management of Obesity

Introduction

Obesity is associated with numerous medical conditions including diabetes, heart disease, hyperlipidemia, sleep apnea, and hypertension.¹ Cardiovascular diseases associated with obesity include atrial fibrillation, heart failure, coronary artery disease, and stroke.¹ Treatment for obesity is multidisciplinary and involves lifestyle modifications, increased physical activity, dietary changes, and pharmacological treatment.¹ For patients with morbid obesity, bariatric surgery is an accepted and effective treatment that has been shown to reduce the incidence of heart failure, myocardial infarction, and stroke in these patients.^1,2

According to the American Society for Metabolic and Bariatric Surgery (ASMBS) database, approximately 279,000 bariatric procedures were performed in 2022.³ Indications for bariatric surgery as stated by the ASMBS were updated that same year.⁴ Individuals with a body mass index (BMI) ≥ 35 kg/m², regardless of presence or absence of medical comorbidities, or with a BMI of 30 to 34.9 kg/m² and metabolic disease should be considered for bariatric surgery.⁴ The BMI threshold for the Asian population is adjusted so that a BMI ≥ 25 kg/m² is defined as clinical obesity.⁴ ASMBS guidelines recommend that patients of Asian descent with a BMI ≥ 27.5 kg/m² should be offered bariatric surgery.⁴

Absolute contraindications for bariatric surgery include the inability to undergo general anesthesia, severe psychiatric illness, and uncontrolled coagulopathy.⁵ All patients who wish to undergo bariatric surgery should undergo a psychosocial and behavioral assessment and meet with a dietitian or nutritionist prior to surgery.⁶

Physicians must take into consideration the invasiveness of the procedure, risk of complications, medical comorbidities, and weight loss desired when deciding which procedure is the safest surgical option.⁶ The Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) bariatric surgical risk calculator is a useful tool surgeons often use to estimate the risk of an unfavorable outcome (ie, complication or death).⁷ Use of the calculator has been shown to be independently associated with reduced risk of serious complications but not with reduced risk of mortality.⁷

Several procedures currently are being performed in the US, with sleeve gastrectomy and gastric bypass being the most predominant. Other procedures such as the duodenal switch, the single anastomosis duodeno-ileostomy with sleeve gastrectomy, the one anastomosis gastric bypass (OAGB), and endoscopic sleeve gastroplasty are performed at much lower rates, but some are increasing rapidly. Laparoscopic gastric banding is no longer performed except by those surgeons on a self-pay basis, as most insurance companies in the US no longer cover it due to its limited efficacy, especially with new medications that offer alternative options.

Sleeve Gastrectomy

Sleeve gastrectomy, also known as vertical sleeve gastrectomy or gastric sleeve, is one of the most common bariatric procedures. In 2022, approximately 160,609 sleeve gastrectomy procedures were performed in the US, accounting for approximately 57.4% of all metabolic and bariatric surgeries.³ Sleeve gastrectomy typically results in 25% to 35% of total body weight loss in long-term studies.^8,9 It has shown fewer postoperative complications and similar effectiveness in excess weight loss as the Roux-en-Y gastric bypass (RYGB) in studies evaluating outcomes after 36 months.¹⁰ However, longer-term studies have shown rates of weight loss failure (defined as excess weight loss percentage < 50%) of 30.4% at 5-year follow-up and 51.4% at 7-year follow-up.⁸ Relative contraindications for sleeve gastrectomy, specifically, include Barrett esophagus and gastroesophageal reflux disease (GERD), suggesting that these patients may be better served with an RYGB to improve reflux symptoms.⁵

The sleeve gastrectomy can be done laparoscopically or robotically. Current data on robotic sleeve gastrectomy (RSG) shows increased operative time, higher leak rates, and higher surgical site infections compared to laparoscopic sleeve gastrectomy (LSG).¹¹ Several studies also have shown an increased hospital cost with RSG compared to LSG, with one institution reporting a 4% increase in total hospital charges.^11,12,13 Due to the higher risk of morbidity and higher costs associated with RSG, the LSG remains the gold standard.¹¹ However, when looking at a more recent subset of data from robotic bariatric surgery, the outcomes from RSG approach that of LSG but are not superior.^11,12 It is possible that with more experience and expertise in this new increasingly popular robotic platform, RSG may become more advantageous after overcoming its current learning curve.

According to data from the Bariatric Outcomes Longitudinal Database (BOLD), the average operative time for LSG is approximately 78 minutes, with a standard deviation of 37.4 minutes.¹⁴ Using an energy device, the gastroepiploic and short gastric vessels are divided along the greater curvature up to the left diaphragmatic crus. A 32F to 40F Bougie measuring device is pressed against the lesser curvature to create a tubularized stomach and help determine where the stomach will be divided. Using a stapler, the stomach is divided superiorly up to the fundus, lateral to the esophagus. The remaining stomach is approximately one-third or less of its original volume (Figure 1). The stomach is a distensible organ and can dilate over some time but will not “stretch out” to its original size, which is falsely believed by some patients who regain weight.

Figure 1

The endoscopic sleeve gastroplasty (ESG) is a less invasive and more cost-effective alternative to the LSG. First described in 2013, the ESG is performed using a flexible endoscope to imbricate the stomach from the incisura to the cardia with full thickness sutures. The ESG preserves gastric tissue and is reversible. In the MERIT (Endoscopic sleeve gastroplasty for treatment of class 1 and 2 obesity) trial, patients who underwent the ESG had an average excess weight loss (the excess weight over the ideal weight for BMI > 25 kg/m²) of 49.2%, whereas patients who were randomized to undergo lifestyle modifications had only seen a 3.2% excess weight loss.¹⁵ Of those patients who underwent ESG, 80% also saw an improvement in one or more metabolic comorbidities in that same trial.¹⁵ The ESG has a similar safety profile as the LSG.¹⁶ However, several studies have reported greater total body weight loss in patients who underwent LSG compared to ESG.^16,17 Although insurance coverage for ESG can be difficult to obtain, most insurance companies will cover LSG if the patient has bariatric benefits. Medicare covers bariatric surgery due to its overall health benefits, although it is quite restrictive when covering weight loss medications for patients without diabetes.

Compared with other bariatric procedures, the sleeve gastrectomy is technically simpler, with a shorter operative time and fewer complications, which may be more beneficial in high-risk surgical patients.^6,10,18 The 30-day mortality after LSG is reportedly 0.02%.¹¹ One of the most feared complications after LSG is staple line leak, which occurs in 0.15% to 2.4% of cases; the majority of current data suggests this is at the lower end of that range.^12,19 Most staple line leaks occur in the proximal stomach and close to the gastroesophageal junction.¹⁹ Staple line leaks may require further treatment by operative or percutaneous drainage and endoscopic stenting.¹⁹ Infection is another potential complication after LSG, with a surgical site infection rate of 0.2%.¹¹ In a 10-year follow-up study, patients who underwent LSG had a 26% remission rate in type 2 diabetes mellitus (T2DM), 19% remission rate in hyperlipidemia, 8% in hypertension, and 16% in obstructive sleep apnea.²⁰ Given the low risk of morbidity and mortality after LSG, high-risk patients with numerous cardiovascular comorbidities who qualify for bariatric surgery should be considered for this surgical approach.

Roux-en-Y Gastric Bypass

The RYGB, first described in the 1960’s, was developed based on patterns of failed weight gain in patients who previously underwent partial gastrectomy.²¹ Today, RYBG is the second most commonly performed bariatric surgery in the US, with 62,907 cases reported in 2022—approximately 22% of all bariatric procedures performed that year.³ While the procedure is similar to sleeve gastrectomy in that it involves creation of a restrictive gastric pouch, it was originally thought to confer added weight loss via malabsorption. However, it is now thought to be due to a metabolic effect, from gut hormonal changes like elevated glucagon-like peptide (GLP) 1 levels. A Roux limb from jejunum, typically about 100 cm to 150 cm in length, is connected to a gastric pouch, thus allowing ingested food to bypass the majority of the stomach and duodenum/proximal jejunum. The earlier contact of food with the small bowel results in a quicker release of satiety hormones and incretin effect for glucose control.²² The residual stomach remains in place and the proximal jejunum is connected to the side of the Roux limb (Figure 2). This additional connection facilitates delivery of digestive enzymes into a more distal common channel, through which the remainder of digestion occurs.

Figure 2

The RYGB has several advantages over sleeve gastrectomy. In patients with preexisting GERD, the RYGB is the preferred bariatric procedure since studies show that those receiving sleeve gastrectomy have significantly more interventions for worsening GERD symptoms and/or development of de novo GERD compared with patients receiving RYGB.²³ One systematic review notes that the odds for revisional surgery to treat GERD in sleeve gastrectomy patients are 11 times higher compared with RYBG patients.²³ Although both procedures may have similar effectiveness in short-term weight loss, a 5-year randomized clinical trial showed greater total estimated weight loss with RYGB (26%) than with sleeve gastrectomy (22.5%).⁹ Furthermore, patients undergoing RYGB had an additional 8.4% average excess body weight loss compared to patients undergoing sleeve gastrectomy.⁹

Findings from a 12-year observational prospective study anticipate that roughly 93% of patients who undergo RYGB will maintain at least 10% weight loss from baseline by year 12, 70% will maintain at least 20% of weight loss, and 40% will maintain at least 30% of weight loss.²⁴ In long-term studies, RYGB is also superior to the sleeve gastrectomy for treatment of metabolic diseases. Patients undergoing RYGB have superior hypertension remission compared to those receiving sleeve gastrectomy (24% vs 8%).²⁰ Also, some literature suggests that RYGB is superior to sleeve gastrectomy in hyperlipidemia remission.^10,25 However, several studies show no statistically significant difference in T2DM resolution between RYGB and sleeve gastrectomy, with one randomized clinical trial noting a remission rate of 33% and 26%, respectively.^10,20,25

As with any surgery, RYGB is not without risk: It has a reported 8% 30-day minor and major combined complication rate, which is higher than that of sleeve gastrectomy and OAGB.^18,26 This more complex procedure is associated with complications including bowel obstruction, internal hernia, stricture, and micronutrient deficiencies.^18,27,28,29 Although these complications are rare, they may require additional interventions for treatment.

Single Anastomosis Duodeno-Ileostomy with Sleeve Gastrectomy and One Anastomosis Gastric Bypass

A relatively recent innovation in the field of bariatric surgery has led to the adaptation of two new surgical techniques endorsed by the ASMBS: single anastomosis duodeno-ileostomy with sleeve gastrectomy (SADI-S) and one anastomosis gastric bypass (OAGB) (Figure 3). Successful bariatric surgery offers effective long-term weight loss with low risk of complications. Of the commonly performed procedures, gastric sleeve offers a relatively low complication rate but has questionable long-term efficacy, whereas RYGB provides effective weight loss but may have long-term complications including internal hernia and chronic marginal ulcers. Both the SADI-S and duodenal switch procedures include sleeve gastrectomy and duodeno-ileostomy. However, in the duodenal switch, the biliopancreatic limb is anastomosed to the distal ileum, creating two reconnection sites, whereas SADI-S has only one reconnection site. Biliopancreatic diversion with duodenal switch is the most metabolically effective surgery but has risks of chronic malabsorption and malnutrition. Compared to these procedures, SADI-S and OAGB offer a middle ground of effective weight loss and relatively low complication rate.

Figure 3

With a SADI-S, the restrictive effect of a gastric sleeve is combined with an intestinal bypass that is more distal than a classic bypass but not as extreme as a duodenal switch (Figure 3). This longer intestinal bypass allows for more effective stimulation of glucagon-like peptide-1 (GLP-1) while avoiding the malnutrition associated with the duodenal switch. A typical SADI-S will have about 250 cm to 300 cm of common intestinal channel, where ingested food can mix with pancreatic and biliary secretions to allow for absorption; this is in contrast to the duodenal switch that usually has only 50 cm to 75 cm of a common channel. Another benefit is that preserving the pylorus with the gastric sleeve anatomy reduces the risk of dumping syndrome and postprandial hypoglycemia. Additionally, although there is a theoretical concern for bile reflux with the operative anatomy, a 2022 meta-analysis of 2,029 patients found a relatively low incidence of bile reflux, approximately 1.2%.³⁰

A 2022 systematic review and meta-analysis of 3,319 patients compared SADI-S to other malabsorptive procedures, such as RYGB and duodenal switch, and found comparable weight loss with a shorter operative duration, shorter hospital stay, and a trend towards fewer complications.³¹ Another meta-analysis from 2021 showed significantly greater weight loss with SADI-S versus RYGB.³² Long-term efficacy of SADI-S has also been demonstrated, with a 2023 systematic review finding that 10-year excess weight loss exceeded 80%.³³ Some of this metabolic success can be explained by the strong GLP-1 response that has been observed after SADI-S.^34,35 Furthermore, animal studies have shown a comparable hormone response after SADI-S compared to RYGB.³⁶ Although the SADI-S currently only represents about 0.5% of bariatric procedures performed annually in the US, the advantages over existing procedures suggested by these studies may lead to its continued adaptation as a bariatric procedure of choice.³

The OAGB procedure has gained popularity outside the US, overtaking RYGB in some countries. Similar to SADI-S, OAGB offers a longer biliopancreatic limb that results in a shorter common intestinal channel compared to RYGB (Figure 4). A 2018 systematic review and meta-analysis comparing OAGB to RYGB in 7,452 patients found that OAGB had a shorter operative time with greater excess weight loss and remission of T2DM but with a similar risk profile.³⁷ Similarly, the YOMEGA (efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass for obesity) prospective randomized controlled trial showed comparable weight loss and diabetes improvement between OAGB and RYGB, although OAGB had a higher rate of nutritional complications, likely related to the longer biliopancreatic limb.³⁸ Additionally, a 2024 publication from the MBSAQIP found a slightly better 30-day outcome compared to RYGB in US data.³⁹ Despite these promising results, OAGB has yet to gain a foothold in the US, with fewer than 1,000 cases performed annually in recent years.³

Figure 4

Some US surgeons have turned to performing RYGB with a longer biliopancreatic limb in an effort to gain some of the metabolic effects of OAGB and potentially improve the incretin effect. However, retrospective data have not found a major difference in GLP-1 levels and metabolic profiles between longer and shorter limb lengths.^40,41 One of the major reasons for this slow adaptation may be that most major insurers do not cover OAGB as an accepted surgical procedure. Perhaps as promising data continue to be gathered and coverage becomes more available, OAGB may gain more popularity in the US. Both the SADI-S and OAGB procedures seem to have fewer problems with chronic anastomotic ulcer and internal hernia, the two most common long-term complications of gastric bypass.

Summary

There are a variety of options for bariatric surgery, each with unique benefits and drawbacks. It is important to emphasize that bariatric surgery improves numerous health outcomes beyond weight loss and metabolic benefits. A 2018 retrospective cohort study comparing 5,301 diabetic patients who underwent bariatric surgery to 14,934 control patients—matched by multiple factors including site, age, sex, BMI, and hemoglobin A1c—found that those receiving bariatric surgery had a reduced risk of macrovascular events (HR 0.60; 95% CI, 0.42-0.86) and coronary artery disease (HR 0.64; 95% CI, 0.42-.99).⁴² These findings are similarly reflected in a 2019 retrospective cohort study comparing 2,287 patients undergoing bariatric surgery to a 1:5 matched control group of 11,435 patients. This study found that bariatric surgery provided an absolute risk reduction of 16.9% (95% CI, 13.1%-20.4%) for the composite end point of major adverse cardiac events, with an additional reduction in all-cause mortality (HR 0.59: 95% CI, 0.48-0.72).⁴³

In addition to its cardiovascular benefits, bariatric surgery results in a significant reduction in risk for multiple forms of cancer. A 2023 meta-analysis that cumulatively compared 511,585 bariatric surgery patients to 1,889,746 control patients found a significant overall reduction in risk of cancer (RR 0.62; 95% CI, 0.46-0.84) as well as cancer-related mortality (RR 0.51; 95% CI, 0.42-0.62),⁴⁴ with this risk reduction extending to multiple specific forms of cancer, including hepatocellular carcinoma, pancreatic cancer, colorectal cancer, and breast and endometrial cancers. Another meta-analysis from 2020 comparing 269,818 bariatric surgery patients to 1,270,086 control patients demonstrated a reduction in all-cause mortality among bariatric surgery patients (OR 0.62; 95% CI, 0.55-0.69) as well as a reduced incidence of T2DM (OR 0.39; 95% CI, 0.18-0.83), hypertension (OR 0.36; 95% CI, 0.32-0.40), and ischemic heart disease (OR 0.46; 95% CI, 0.29-0.73).⁴⁵ These findings all represent substantial and clinically significant improvements in multiple health outcomes as a result of bariatric surgery. Given these data, it is not surprising that the number of bariatric procedures performed per year continues to steadily increase.³

Bariatric surgery has come a long way from the original open surgery with large incisions, to minimally invasive surgery with laparoscopy, robotics, and now advanced endoscopic procedures. The majority of bariatric surgery procedures in the US are done at accredited centers or “centers of excellence.” Major postoperative outcomes are tracked on all patients. In recent years, several publications have shown very favorable outcomes with low complication rates (Table 1). Numerous publications also show significantly improved outcomes in cardiovascular disease, diabetes, cancer, and even mortality with bariatric surgery.^1,2,10,46,47 Several randomized trials support surgical intervention as well.^9,15,48 Improved outcomes are also seen with weight loss from obesity medications.⁴⁹

Conclusion

With more effective medical therapies, we hope to see continually improved outcomes with weight loss in various health conditions. For now, however, bariatric surgery is an effective and efficient way to lose a substantial amount of weight and see significant improvement in comorbidities and even mortality. Due to this efficacy and cost effectiveness, many insurance companies, including Medicare, currently cover bariatric surgery but have more restrictions on the use of medications for obesity, especially for nondiabetic patients.

Key Points

• Bariatric surgery has been shown to reduce the incidence of heart failure, myocardial infarction, and stroke in patients with obesity.

• Sleeve gastrectomy, the most common bariatric procedure performed in the US, has a low morbidity and mortality rate.

• Single anastomosis duodeno-ileostomy with sleeve gastrectomy and one anastomosis gastric bypass are newer procedures not often performed in the US, but they appear to result in greater excess weight loss compared to Roux-en-Y gastric bypass.

Competing Interests

The authors have no competing interests to declare.