Over 15 million adult Americans (6.6% of the population) had a BMI > 40 kg/m2 in 2013, and the rate of obesity continues to rise.1 Obesity is associated with increased morbidity and mortality.2 Approximately 179,000 weight loss procedures were performed in the United States in 2013, and strong data now demonstrate that bariatric surgery decreases morbidity and mortality in obese patients.3
The first published bariatric case series was performed in the early 1960s by Payne and colleagues.4 The authors described the jejunocolic bypass, an operation aimed purely at malabsorption, that consisted of dividing the proximal jejunum 35–50 cm from the ligament of Treitz and anastomosing it to the proximal transverse colon.4 Although this resulted in successful weight loss, virtually all the patients suffered from diarrhea, dehydration, and severe electrolyte imbalances.5 In an attempt to avoid these complications, jejunoileal bypass replaced the jejunocolic, with an anastomosis performed 10 cm proximal to the ileocecal valve, and with the bypassed small intestine anastomosed to the transverse or sigmoid colon. This operation, however, was also fraught with complications, including diarrhea, dehydration, vitamin and mineral deficiencies, protein depletion, polyarthralgia, hepatic insufficiency, and ultimately, weight regain.6,7
The high morbidity rate of these procedures led to the exploration of weight loss operations that combined malabsorption with restriction. Biliopancreatic diversion with partial distal gastrectomy and Roux-en-Y reconstruction became popular in the 1970s. Subsequently, the biliopancreatic diversion with duodenal switch, where a sleeve gastrectomy maintained the integrity of the pylorus and proximal duodenum, became popular in the late 1990s. These procedures led not only to significant excess weight loss, but also to very high rates of remission of diabetes mellitus, hypertension, and hyperlipidemia.8,9,10 The Roux-en-Y gastric bypass configuration (RYGB) also appeared in the 1970s, proving to be superior to jejunoileal bypass with regard to its complication rates.11,12 Unfortunately these operations still carried significant malabsorptive side effects, leading some surgeons to favor purely restrictive procedures, such as nonadjustable vertical banded gastroplasty (VBG), and later, adjustable gastric banding (AGB). These are less successful than the RYGB in weight loss and reduction of obesity-related comorbidities such as diabetes mellitus. They also have their own procedure-related complications, including staple line dehiscence or stoma stenosis after VBG, and band slippage or erosion with the AGB.6,13,14
The final bariatric procedure that was initially conceived as a solely restrictive solution, but which has since been shown to induce concurrent metabolic changes, is the standalone sleeve gastrectomy, in which the fundus and the lateral 80% of the body of the stomach is resected. It was initially used in superobese patients with BMI > 50 as a first stage before proceeding with duodenal switch or gastric bypass. However, over the last 10 years the laparoscopic version of this operation [laparoscopic sleeve gastrectomy (LSG)] has become the most prevalent surgical approach to morbid obesity, surpassing the laparoscopic RYGB and AGB. Although unequivocal long-term data about the outcomes of LSG has yet to be published, middle-term data discussed in this chapter demonstrate that it is a safe procedure with weight loss outcomes better than those after gastric banding, although slightly worse than those after RYGB.15,16
The improved safety profile of the most frequently performed weight loss procedures today, LRYGB and LSG, is due in part to a major focus on quality improvement measures such as American College of Surgeons Bariatric Surgery Center Network (ACS-BSCN) and the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP), and in part due to the evolution of laparoscopy and advanced surgical techniques and technology. The studies below detail the outcomes of the most prevalent weight loss surgical techniques today, as well as their impact on what has become one of the most important public health issues.
Plasma ghrelin levels after diet-induced weight loss or gastric bypass surgery.
Cummings DE, Weigle DS, Frayo RS, Breen PA, Ma MK, Dellinger EP, Purnell JQ
NEJM. 2002;346(21):1623–1630.Takeaway Point: Bariatric surgery suppresses ghrelin levels, which may contribute to weight loss.
Commentary: Meal volume restriction induces early satiety after gastric bypass, facilitating weight loss. The other mechanisms for weight loss after bariatric surgery, however, have not been clearly explained. The authors presented a matched control trial that examined the effect of weight loss associated with Roux-en-Y gastric bypass versus diet alone on the 24-hour ghrelin profile. They discovered that bariatric surgery patients have markedly decreased levels of ghrelin, which, unlike those in matched weight controls, do not oscillate in relation to meals. This provides major insight into one mechanism by which bariatric surgery leads to long-term appetite suppression and weight loss. Additionally, it sheds light on why diet-induced weight loss is extremely difficult to maintain, by demonstrating that plasma ghrelin levels rise after such weight loss.
Introduction: Ghrelin is a peptide hormone secreted in the stomach and duodenum that circulates under fasting conditions and acts on the hypothalamus to stimulate appetite. It also participates in long-term regulation of body weight. Given that gastric bypass excludes most of the stomach and the duodenum, the authors postulated that RYGB may reduce circulating ghrelin levels. This, in turn, may contribute to the durability of weight loss after bariatric surgery, as compared with diet-induced weight loss.
Objectives: To compare 24-hour plasma ghrelin levels in subjects before and after gastric bypass, before and after diet-induced weight loss, and normal-weight subjects.
Trial Design: Matched control study.
Inclusion Criteria: Age ≥18, stable body weight for at least 3 months.
Exclusion Criteria: Chronic medical or psychiatric illness, pregnancy, tobacco use, substance abuse, consumption of more than two alcoholic drinks per day, aerobic exercise >30 minutes 3 times per week, and previous gastrointestinal surgery.
Intervention: Subjects were admitted for an overnight fast, and plasma ghrelin levels were measured every 30 minutes between 8 AM and 9 PM (with three meals during the day), then hourly until 8 AM. The ghrelin profiles were compared between the subjects who had undergone a Roux-en-Y gastric bypass 9–31 months previously, BMI-matched obese subjects who had recently lost weight through a supervised dieting program, and a control group of normal-weight subjects.
Primary Endpoint: 24-hour plasma ghrelin profiles.
Secondary Endpoints: Weight loss, leptin levels, insulin levels, blood pressure, insulin sensitivity, lipid profiles.
Sample Size: 13 obese subjects who had undergone a 6-month dietary program for weight loss, 5 subjects after gastric bypass, and 10 normal-weight controls at a single university.
Statistical Analysis: Two-tailed, paired Student’s t-tests, univariate linear regression.
Baseline Data: Aside from the difference in BMI between the normal-weight group and the two obese subjects groups, there were no baseline differences.
Outcomes: Plasma ghrelin levels in obese patients rose just before and fell shortly after each meal. These fluctuations were not present in the gastric bypass group. The subjects who lost an average of 17% of body weight through dieting experienced a 24% increase in the area under the curve of the ghrelin 24-hour profile (p 0.006). In contrast, this area was 77% lower in the subjects who had undergone gastric bypass than in normal-weight controls (p < 0.0001), and 72% lower than in obese controls (p 0.01). The gastric bypass patients retained normal postprandial elevations of insulin and diurnal variations in leptin levels. In the diet group, weight loss was associated with significant decreases in adipocyte volume, leptin levels, fasting insulin levels, and blood pressure, in addition to improvement in insulin sensitivity and lipid levels.
Conclusion: Circulating ghrelin levels increase with diet-induced weight loss and drastically decrease after gastric bypass. This likely contributes to the weight-reducing effect of the operation.
Limitations: The patients in the surgical group underwent gastric bypass a mean of 1.4 ± 0.4 years previously. Therefore, no conclusions regarding the long-term trend of ghrelin levels after bariatric surgery are appropriate at this time. Since only gastric bypass patients were included in the study, it is also unclear whether the findings can be extrapolated to other bariatric procedures. Furthermore, exclusion of patients with chronic illnesses may limit the generalizability to the obese population, which has high rates of chronic conditions such as diabetes mellitus, hypertension, and hyperlipidemia. The sample size was small.
Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery.
Sjöström L, Lindroos AK, Peltonen M, Torgerson J, Bouchard C, Carlsson B, Dahlgren S, Larsson B, Narbro K, Sjöström CD, Sullivan M, Wedel H, Swedish Obese Subjects Study Scientific Group
NEJM. 2004;351(26):2683–2693.Takeaway Point: Bariatric surgery results in long-term weight loss and improvement in associated comorbidities.
Commentary: The Swedish Obese Subjects (SOS) trial is the largest prospective study of bariatric surgery outcomes to date. The authors’ 10-year data show the dramatic effect of surgical weight loss on patients’ morbidity and mortality. Specifically, this study addressed the effect of bariatric surgery on obesity-related comorbidities, and demonstrated long-term sustainability of this impact. It is interesting to note that not all risk factors seem to improve permanently (eg, hyperlipidemia), and the mechanisms for these changes have not been entirely elucidated. Overall, however, these findings have been essential in validating bariatric surgery interventions as favorable and lasting options for the treatment of morbid obesity.
Introduction: It is known that obesity is linked to increased morbidity and mortality. The former is postulated to result largely from associated comorbidities, including diabetes, hypertension, and hyperlipidemia. Surgically induced weight loss, however, had not been previously shown to have a long-lasting effect on these conditions.
Objectives: To assess changes in cardiovascular risk factors over 2-and 10-year follow-up periods in bariatric patients and medically treated matched controls.
Trial Design: Prospective, matched control surgical intervention trial.
Inclusion Criteria: BMI ≥34 for men or ≥38 for women, age 37–60. The subjects were matched according to an algorithm composed of 18 demographic and clinical variables.
Exclusion Criteria: Previous surgery for gastric or duodenal ulcer, previous bariatric surgery, gastric ulcer during the past 6 months, ongoing malignancy, active malignancy during the past 5 years, myocardial infarction during the past 6 months, bulimic eating pattern, drug or alcohol abuse, psychiatric or cooperation problems contraindicating bariatric surgery, and other contraindicating conditions such as continuous glucocorticoid or anti-inflammatory treatment.
Intervention: The surgical patients and their matched controls had physical exams and laboratory workup performed at each scheduled visit. Surgically treated patients underwent gastric banding, vertical banded gastroplasty, or gastric bypass. Matched controls received nonstandardized medical treatment for their obesity and existing comorbidities.
Primary Endpoint: Overall mortality (addressed in the main SOS study; see c, below).
Secondary Endpoints: Changes in body weight, risk factors, energy intake, and physical activity; incidence of risk factors at time of follow-up in subjects who did not have these conditions at baseline; rates of improvement in comorbidities over the 2- and 10-year follow-up periods in those patients who had them at baseline.
Sample Size: 4047 subjects who had been enrolled into the SOS study from 25 surgical departments in Sweden and followed for at least 2 years, and 1703 subjects who had been enrolled for at least 10 years before January 2004. Follow-up was 86.6% at 2 years and 74.5% at 10 years.
Statistical Analysis: Analysis of covariance, logistic regression.
Baseline Data: At the time of the matching examination, the patients in the surgery group were heavier (119.2 vs. 116.1 kg, p < 0.001), younger (46.1 vs. 47.4 years, p = 0.005), and had a higher plasma insulin level (22.8 vs. 20.9 mU/L, p = 0.009).
Outcomes: Bariatric surgery patients lost significantly more weight, and this difference was maintained at 2 and 10 years of follow-up (+0.1% in controls vs. –23.4% in surgery group, and +1.6% in controls vs. –16.1% in surgery group, respectively; p < 0.001). Surgical patients also had a lower energy intake and higher proportion of physically active subjects than did the control group over the 10-year period. There were significant decreases in serum glucose, insulin, uric acid, triglycerides, total cholesterol, and systolic/diastolic blood pressure, with a favorable increase in high-density lipoprotein (HDL) cholesterol at 2 years (p < 0.05). These differences remained significant for glucose, insulin, uric acid, triglycerides, HDL, and diastolic blood pressure at 10 years (p < 0.05), reflecting recovery from diabetes, hyperuricemia, hypertriglyceridemia, and hypertension. The new incidence rates of diabetes, hypertriglyceridemia, and hyperuricemia were also lower in the surgically treated group than in the control group at 2 and 10 years.
Conclusion: Obese patients experience greater long-term weight loss, more physical activity, lower energy intake, and recovery from risk factors such as diabetes, hyperuricemia, hypertriglyceridemia, low HDL, and hypertension after bariatric surgery when compared to standard lifestyle management.
Limitations: Incomplete follow-up at 10 years could have contributed to bias, as could lack of randomization and the presence of some heterogeneity between the groups. Medical management was not standardized and ranged from “sophisticated lifestyle intervention and behavior modification to, in some practices, no treatment whatsoever” (p. 2685).
Effects of bariatric surgery on mortality in Swedish obese subjects.
Sjöström L, Narbro K, Sjöström CD, Karason K, Larsson B, Wedel H, Lystig T, Sullivan M, Bouchard C, Carlsson B, Bengtsson C, Dahlgren S, Gummesson A, Jacobson P, Karlsson J, Lindroos AK, Lönroth H, Näslund I, Olbers T, Stenlöf K, Torgerson J, Agren G, Carlsson LM, Swedish Obese Subjects Study
NEJM. 2007;357(8):741–752.Takeaway Point: Bariatric surgery is associated with long-term weight loss and decreased mortality.
Commentary: The authors present a large, multi-institution, prospective, controlled trial comparing overall mortality of obese subjects undergoing bariatric surgery with those who received conventional medical treatment. Although the trial was not powered to prove that weight loss itself was linked to improved survival, it clearly showed that bariatric surgery was associated with sustained weight loss and lower mortality in long-term follow-up. Further investigations should examine the mechanisms of this effect; however, this study widely established bariatric surgery as a valid life-prolonging intervention. It is possible that the positive effect on significant medical comorbidities such as diabetes mellitus, hypertension, and hyperlipidemia that has been demonstrated by some of the trials discussed in this chapter (see h, below and b, above) may contribute to the reduction in mortality.
Introduction: Although a number of large long-term investigations have demonstrated an association between obesity and increased mortality, definitive data regarding the effect of weight loss on survival was not available prior to the publication of this study. Several retrospective cohort studies had suggested that intentional weight loss may be associated with lower rates of mortality, but prospective data from large sample sizes were lacking.
Objectives: To examine the effects of intentional weight loss on mortality by evaluating whether bariatric surgery is associated with lower mortality than conventional nonoperative treatment of obesity.
Trial Design: Prospective matched control trial.
Inclusion Criteria: Age 37–60, BMI ≥ 34 for men and ≥ 38 for women.
Exclusion Criteria: Previous surgery for gastric or duodenal ulcer, previous bariatric surgery, gastric ulcer during the past 6 months, ongoing malignancy, active malignancy during the past 5 years, myocardial infarction during the past 6 months, bulimic eating pattern, drug or alcohol abuse, psychiatric or cooperation problems contraindicating bariatric surgery, and other contraindicating conditions such as continuous glucocorticoid or anti-inflammatory treatment.
Intervention: Of the 2010 patients in the surgical cohort, 376 received a gastric band, 1369 underwent vertical banded gastroplasty, and 265 underwent a Roux-en-Y gastric bypass. 2037 matched controls were treated with a conventional medical approach beginning the day of the surgical cohort’s operation.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
