Gastrointestinal Surgery: Cardiovascular Risk Reduction and Improved Long-Term Survival in Patients with Obesity and Diabetes

Clinical Practice Guidelines for the Perioperative Nutrition, Metabolic, and Nonsurgical Support of Patients Undergoing Bariatric Procedures - 2019 Update: Cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic and Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists

OBJECTIVE

The development of these updated clinical practice guidelines (CPGs) was commissioned by the American Association of Clinical Endocrinologists (AACE), The Obesity Society (TOS), American Society for Metabolic and Bariatric Surgery (ASMBS), Obesity Medicine Association (OMA), and American Society of Anesthesiologists (ASA) Boards of Directors in adherence with the AACE 2017 protocol for standardized production of CPGs, algorithms, and checklists.

METHODS

Each recommendation was evaluated and updated based on new evidence from 2013 to the present and subjective factors provided by experts.

RESULTS

New or updated topics in this CPG include: contextualization in an adiposity-based chronic disease complications-centric model, nuance-based and algorithm/checklist-assisted clinical decision-making about procedure selection, novel bariatric procedures, enhanced recovery after bariatric surgery protocols, and logistical concerns (including cost factors) in the current health care arena. There are 85 numbered recommendations that have updated supporting evidence, of which 61 are revised and 12 are new. Noting that there can be multiple recommendation statements within a single numbered recommendation, there are 31 (13%) Grade A, 42 (17%) Grade B, 72 (29%) Grade C, and 101 (41%) Grade D recommendations. There are 858 citations, of which 81 (9.4%) are evidence level (EL) 1 (highest), 562 (65.5%) are EL 2, 72 (8.4%) are EL 3, and 143 (16.7%) are EL 4 (lowest).

CONCLUSIONS

Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity. Clinical decision-making should be evidence based within the context of a chronic disease. A team approach to perioperative care is mandatory, with special attention to nutritional and metabolic issues.

Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures - 2019 update: cosponsored by American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists

OBJECTIVE

The development of these updated clinical practice guidelines (CPG) was commissioned by the American Association of Clinical Endocrinologists, The Obesity Society, the American Society of Metabolic and Bariatric Surgery, the Obesity Medicine Association, and the American Society of Anesthesiologists boards of directors in adherence to the American Association of Clinical Endocrinologists 2017 protocol for standardized production of CPG, algorithms, and checklists.

METHODS

Each recommendation was evaluated and updated based on new evidence from 2013 to the present and subjective factors provided by experts.

RESULTS

New or updated topics in this CPG include contextualization in an adiposity-based, chronic disease complications-centric model, nuance-based, and algorithm/checklist-assisted clinical decision-making about procedure selection, novel bariatric procedures, enhanced recovery after bariatric surgery protocols, and logistical concerns (including cost factors) in the current healthcare arena. There are 85 numbered recommendations that have updated supporting evidence, of which 61 are revised and 12 are new. Noting that there can be multiple recommendation statements within a single numbered recommendation, there are 31 (13%) Grade A, 42 (17%) Grade B, 72 (29%) Grade C, and 101 (41%) Grade D recommendations. There are 858 citations, of which 81 (9.4%) are evidence level (EL) 1 (highest), 562 (65.5%) are EL 2, 72 (8.4%) are EL 3, and 143 (16.7%) are EL 4 (lowest).

CONCLUSIONS

Bariatric procedures remain a safe and effective intervention for higher-risk patients with obesity. Clinical decision-making should be evidence-based within the context of a chronic disease. A team approach to perioperative care is mandatory with special attention to nutritional and metabolic issues.

Roux-en-Y gastric bypass surgery reprograms enterocyte triglyceride metabolism and postprandial secretion in rats

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) surgery produces rapid and persistent reductions in plasma triglyceride (TG) levels associated with fewer cardiovascular events. The mechanisms of the reduction in systemic TG levels remain unclear. We hypothesized that RYGB reduces intestinal TG secretion via altered enterocyte lipid handling.

METHODS

RYGB or Sham surgery was performed in diet-induced obese, insulin-resistant male Sprague-Dawley rats. First, we tested whether RYGB reduced test meal-induced TG levels in the intestinal lymph, a direct readout of enterocyte lipid secretion. Second, we examined whether RYGB modified TG enterocyte secretion at the single lipid level and in comparison to other lipid subclasses, applying mass spectrometry lipidomics to the intestinal lymph of RYGB and Sham rats (0-21 days after surgery). Third, we explored whether RYGB modulated the metabolic characteristics of primary enterocytes using transcriptional and functional assays relevant to TG absorption, reesterification, storage in lipid droplets, and oxidation.

RESULTS

RYGB reduced overall postprandial TG concentrations compared to Sham surgery in plasma and intestinal lymph similarly. RYGB reduced lymphatic TG concentrations more than other lipid subclasses, and shifted the remaining TG pool towards long-chain, unsaturated species. In enterocytes of fasted RYGB rats, lipid uptake was transcriptionally (Fatp4, Fabp2, Cd36) and functionally reduced compared to Sham, whereas TG reesterification genes were upregulated.

CONCLUSION

Our results show that RYGB substantially reduces intestinal TG secretion and modifies enterocyte lipid absorption and handling in rats. These changes likely contribute to the improvements in the plasma TG profile observed after RYGB in humans.

4-Year Changes in Sex Hormones, Sexual Functioning, and Psychosocial Status in Women Who Underwent Bariatric Surgery

BACKGROUND

Initial weight loss after bariatric surgery has been associated with improvements in reproductive hormones and sexual functioning in women. Few studies have investigated the durability of these changes.

OBJECTIVES

The objective of this paper is to investigate changes in sex hormones, sexual functioning, and relevant psychosocial constructs over 4 years in women who underwent bariatric surgery.

SETTING

The setting is a prospective cohort of 106 women from the Longitudinal Assessment of Bariatric Surgery consortium.

METHODS

Changes in sex hormones were assessed by blood assay. Sexual functioning, quality of life (QOL), body image, depressive symptoms, and marital adjustment were assessed by psychometric measures.

RESULTS

Women lost on average (95% confidence interval) 32.3% (30.4%, 34.3%) at postoperative year 3 and 30.6% (28.5%, 32.8%) at postoperative year 4. Compared to baseline, women experienced significant changes at 4 years in all hormones assessed, except estradiol. Women reported significant improvements in sexual functioning (i.e., arousal, desire, and satisfaction) through year 3, but these changes were not maintained through year 4. Changes in relationship quality followed a similar pattern. Improvements in physical aspects of QOL, body image, and depressive symptoms were maintained through 4 years.

CONCLUSIONS

Improvements in reproductive hormones and physical aspects of QOL, body image, and depressive symptoms were maintained 4 years after bariatric surgery. Improvements in sexual functioning, relationship satisfaction, and mental components of QOL eroded over time.

Commercial Very Low Energy Meal Replacements for Preoperative Weight Loss in Obese Patients: a Systematic Review

BACKGROUND

This systematic review assessed feasibility and effectiveness of preoperative meal replacements to improve surgical outcomes for obese patients.

METHODS

PRISMA guidelines were followed and electronic databases searched for articles between January 1990 and March 2015.

RESULTS

Fifteen studies (942 participants including 351 controls) were included, 13 studies (n = 750) in bariatric patients. Adverse effects and dropout rates were minimal. Ten out of 14 studies achieved 5-10 % total weight loss. Six of six studies reporting liver volume achieved 10 % reduction. Endpoints for perioperative risks and outcomes were too varied to support definitive risk benefit.

CONCLUSIONS

Commercial meal replacements are feasible, have minimal side effects and facilitate weight loss and liver shrinkage in free-living obese patients awaiting elective surgery. A reduction in surgical risk is unclear.

All-Cause and Cause-Specific Mortality Associated with Bariatric Surgery: A Review

The question of whether or not nonsurgical intentional or voluntary weight loss results in reduced mortality has been equivocal, with long-term mortality following weight loss being reported as increased, decreased, and not changed. In part, inconsistent results have been attributed to the uncertainty of whether the intentionality of weight loss is accurately reported in large population studies and also that achieving significant and sustained voluntary weight loss in large intervention trials is extremely difficult. Bariatric surgery has generally been free of these conflicts. Patients voluntarily undergo surgery and the resulting weight is typically significant and sustained. These elements, combined with possible non-weight loss-related mechanisms, have resulted in improved comorbidities, which likely contribute to a reduction in long-term mortality. This paper reviews the association between bariatric surgery and long-term mortality. From these studies, the general consensus is that bariatric surgical patients have: 1) significantly reduced long-term all-cause mortality when compared to severely obese non-bariatric surgical control groups; 2) greater mortality when compared to the general population, with the exception of one study; 3) reduced cardiovascular-, stroke-, and cancer-caused mortality when compared to severely obese non-operated controls; and 4) increased risk for externally caused death such as suicide.

Weight Loss and the Prevention and Treatment of Type 2 Diabetes Using Lifestyle Therapy, Pharmacotherapy, and Bariatric Surgery: Mechanisms of Action

Weight loss, whether achieved by lifestyle intervention, pharmacotherapy, or bariatric surgery, is highly effective as a primary interventional strategy in both the prevention and treatment of type 2 diabetes. In high-risk patients with prediabetes and/or metabolic syndrome, weight loss effectively prevents progression to type 2 diabetes mellitus (T2DM) and improves cardiovascular risk factors. These benefits are the result of improvements in insulin resistance, which is central to the pathophysiology of cardiometabolic disease. In patients with T2DM, weight loss improves glycemia, while reducing the need for conventional glucose-lowering medicines, by affecting all three processes that produce and sustain the hyperglycemic state, namely via increments in peripheral insulin sensitivity with improvements in insulin signal transduction at the cellular level, more robust insulin secretory responses, and reduced rates of hepatic glucose production. In both nondiabetic and diabetic subjects, hypocaloric feeding (e.g., treatment with very low-calorie diet or bariatric surgery) produces a rapid improvement in insulin sensitivity due to mobilization of fat from the intramyocellular, intrahepatocellular, and intra-abdominal compartments, and via a more long-term mechanism that correlates with the loss of total body fat. In diabetes, by improving glycemia, weight loss also enhances glucose homeostasis by reversing the defects in insulin action and secretion attributable to glucose toxicity. Regardless of the therapeutic approach, weight loss of ∼ 10 % maximally prevents future diabetes in patients with prediabetes or metabolic syndrome. In T2DM, greater degrees of weight loss lead to progressive improvements in glucose homeostasis. Therefore, when accompanied by greater weight loss, the metabolic benefits following bariatric surgery are generally more pronounced than those achieved following lifestyle and medical treatment. In addition, the mechanisms by which bariatric operations improve diabetes may include both weight-dependent and weight-independent mechanisms, and the latter may involve changes in gut hormones, bile acids, or gut microflora.

Development of minimally invasive techniques for management of medically-complicated obesity

The field of bariatric surgery has been rapidly growing and evolving over the past several decades. During the period that obesity has become a worldwide epidemic, new interventions have been developed to combat this complex disorder. The development of new laparoscopic and minimally invasive treatments for medically-complicated obesity has made it essential that gastrointestinal physicians obtain a thorough understanding of past developments and possible future directions in bariatrics. New laparoscopic advancements provide patients and practitioners with a variety of options that have an improved safety profile and better efficacy without open, invasive surgery. The mechanisms of weight loss after bariatric surgery are complex and may in part be related to altered release of regulatory peptide hormones from the gut. Endoscopic techniques designed to mimic the effects of bariatric surgery and endolumenal interventions performed entirely through the gastrointestinal tract offer potential advantages. Several of these new techniques have demonstrated promising, preliminary results. We outline herein historical and current trends in the development of bariatric surgery and its transition to safer and more minimally invasive procedures designed to induce weight loss.

Preventing type 2 diabetes, CVD, and mortality: surgical versus non-surgical weight loss strategies

The burden of type 2 diabetes is increasing. The prevention of the disease, improvement of metabolic control, and more importantly reduction in mortality remain a challenge for primary care doctors, diabetologists, researchers and policymakers. In this article, the available literature is reviewed with a focus on recent developments. Comparison between medical and surgical interventions is performed using mainly head-to-head trials where possible. Weight loss surgery is effective for glycaemic control. The need for level 1 data with hard end points such as cardiovascular risk and mortality is highlighted, and the prospect of the combination of existing therapy options is emphasized.

A complications-based clinical staging of obesity to guide treatment modality and intensity

PURPOSE OF REVIEW

The current medical model for obesity management is BMI-centric because BMI is the predominant measure used to gauge disease severity, as well as indications for various treatment modalities. Recent advancements in therapy and understanding of the relationship between BMI and obesity-related complications call for a re-examination of this approach.

RECENT FINDINGS

Advancements in treatment, including the recent approval of two new weight loss medications in the USA, have enabled development of new medical models for management of obesity. On the basis of accumulating data demonstrating the benefits of weight loss regarding multiple obesity-related complications (e.g., diabetes prevention, type 2 diabetes mellitus, cardiovascular disease risk, nonalcoholic steatohepatitis, sleep apnea), a complications-centric model is proposed that employs weight loss as a tool to treat and prevent obesity comorbidities. This model assures that the aggressiveness of therapy is commensurate with disease severity, and that therapy is directed at those obese patients who will benefit most from weight loss therapy. The treatment algorithm is comprehensive in addressing complications and quantitative when possible in the staging of risk or disease severity.

SUMMARY

A complications-centric approach to obesity management identifies patients who will benefit most from weight loss, and optimizes patient outcomes, benefit/risk ratio, and the cost-effectiveness of interventions.

Forensic Considerations in Bariatric Surgery Patients

Bariatric surgery is gaining in popularity in the United States and around the world as a treatment for morbid obesity. Patients seek surgery in order to lose weight and limit the long-term effects of insulin-resistant diabetes, heart disease and lung disease, including risk of sudden death. While gastric bypass in patients with morbid obesity can reduce the risk of diabetes and myocardial infarction to population levels, the risk of death remains increased. These patients may die suddenly and unexpectedly as a direct result of surgery, as an indirect result of surgery, or of end-organ damage wrought by years of obesity, completely unrelated to the surgery. Proper forensic pathologic assessment of these patients requires an understanding of the anatomic changes caused by bariatric surgery, the complications and the metabolic consequences of the different procedures. In order to better understand this subgroup of patients, a search of the peer-reviewed medical literature at the National Library of Medicine was conducted for articles using the keywords bariatric, surgery, gastric bypass, autopsy, review, toxicology, alcohol, drug, ethanol, absorption, elimination, litigation, forensic, and death. This review outlines the most common laparoscopic and open surgical procedures; the common immediate post-surgical complications that lead to morbidity and mortality; forensic toxicological considerations in bariatric patients; and the long-term complications and other causes that could lead to unexpected death in these patients.