Because weight loss through diet and exercise is difficult and studies suggest that obese patients tend to regain lost weight, interest in bariatric surgery has been increasing. In spite of its well-established benefits, however, bariatric surgery is not without risk. Healthcare professionals who hope to improve outcomes in severely obese patients need a clear understanding of how bariatric surgery fits into the care of these challenging patients. This includes the likely extent of weight loss, the expected benefits, the risks both during and after the surgery, and the long-term effects on nutrition and on quality of life. This proposed course will address the indications for bariatric surgery, the types of procedures currently in use, the specific benefits for the treatment of obesity-related diseases, and the short- and long-term risks. It will also briefly address other treatments for severe obesity, including medication and therapeutic lifestyle change.
This course is designed for healthcare professionals involved in the care of patients for whom surgical intervention is indicated for the treatment of obesity.
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Severely obese patients who have lost substantial amounts of weight following bariatric surgeries have experienced significant remission of obesity-related conditions, but the procedures are not entirely without risk. The purpose of this course is to educate healthcare professionals about the role of bariatric surgery in the treatment of obesity, with particular attention to outcomes for obesity-related diseases.
Upon completion of this course, you should be able to:
- Outline the epidemiology of obesity and bariatric surgery in the United States.
- Describe the different types of bariatric surgery and the criteria for patients who may be candidates for weight-loss surgeries.
- Discuss possible perioperative complications of bariatric surgery.
- Review the care of patients after bariatric surgery, including expected weight loss.
- State the effects that bariatric surgery may have on obesity-related diseases, with particular attention to cardiovascular risk factors.
- Describe potential long-term complications of bariatric surgery, including nutritional deficiencies and medication absorption issues.
- Identify options for non-surgical treatments for obesity, including lifestyle change and weight-loss medication.
John J. Whyte, MD, MPH, is currently the Director of Professional Affairs and Stakeholder Engagement at the FDA's Center for Drug Evaluation and Research. Previously, Dr. Whyte served as the Chief Medical Expert and Vice President, Health and Medical Education at Discovery Channel, part of the media conglomerate Discovery Communications. In this role, Dr. Whyte developed, designed, and delivered educational programming that appeals to both a medical and lay audience.
Prior to this, Dr. Whyte was in the Immediate Office of the Director at the Agency for Healthcare Research Quality. He served as Medical Advisor/Director of the Council on Private Sector Initiatives to Improve the Safety, Security, and Quality of Healthcare. Prior to this assignment, Dr. Whyte was the Acting Director, Division of Medical Items and Devices in the Coverage and Analysis Group in the Centers for Medicare & Medicaid Services (CMS). CMS is the federal agency responsible for administering the Medicare and Medicaid programs. In his role at CMS, Dr.Whyte made recommendations as to whether or not the Medicare program should pay for certain procedures, equipment, or services. His division was responsible for durable medical equipment, orthotics/prosthetics, drugs/biologics/therapeutics, medical items, laboratory tests, and non-implantable devices. As Division Director as well as Medical Officer/Senior Advisor, Dr. Whyte was responsible for more national coverage decisions than any other CMS staff.
Dr. Whyte is a board-certified internist. He completed an internal medicine residency at Duke University Medical Center as well as earned a Master’s of Public Health (MPH) in Health Policy and Management at Harvard University School of Public Health. Prior to arriving in Washington, Dr. Whyte was a health services research fellow at Stanford and attending physician in the Department of Medicine. He has written extensively in the medical and lay press on health policy issues.
Contributing faculty, John J. Whyte, MD, MPH, has disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.
Ronald Runciman, MD
Jane C. Norman, RN, MSN, CNE, PhD
Alice Yick Flanagan, PhD, MSW
Chris Keegan, CST, MS
The division planners have disclosed no relevant financial relationship with any product manufacturer or service provider mentioned.
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- BARIATRIC SURGERY
- COMPLICATIONS OF BARIATRIC SURGERY
- CARING FOR PATIENTS AFTER BARIATRIC SURGERY
- WEIGHT LOSS AFTER BARIATRIC SURGERY
- EFFECTS ON OBESITY-RELATED CONDITIONS
- LONG-TERM COMPLICATIONS
- NON-SURGICAL WEIGHT-LOSS METHODS
- Works Cited
- Evidence-Based Practice Recommendations Citations
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#90981: Bariatric Surgery for Weight Loss
Obesity is a well-recognized problem in the United States, affecting 35.1% of adults and 18.4% of youth . Health problems related to obesity, including diabetes, heart disease, arthritis, and certain cancers, produce significant disability. More than 100,000 deaths each year are directly related to obesity .
Many of the health problems related to obesity can be ameliorated or eliminated with weight loss and exercise. The Diabetes Prevention Program demonstrated that, among obese adults at high risk of diabetes, lifestyle changes, including diet and exercise, leading to an average weight loss of about 7% of total body weight could delay or prevent the onset of type 2 diabetes [3,4]. In a study of more than 43,000 overweight white women, intentional weight loss in those with obesity-related conditions was associated with reductions in mortality . In the Nurses' Health Study, weight loss was associated with a decreased risk for hypertension, while weight gain increased the risk .
Studies of bariatric surgery have shed additional light on the benefits of weight loss. Severely obese patients who have lost substantial amounts of weight following gastric bypass, gastric banding, or other bariatric surgeries have experienced significant remission of obesity-related conditions [7,8,9,10,11,12,13,14]. There is also ongoing investigation into the possibility that certain surgical procedures confer benefit beyond that attributable to weight loss alone.
Because weight loss through diet and exercise is difficult and studies suggest that obese patients tend to regain lost weight, interest in bariatric surgery has been increasing. In spite of its well-established benefits, however, bariatric surgery is not without risk. Healthcare professionals who hope to improve outcomes in severely obese patients need a clear understanding of how bariatric surgery fits into the care of these challenging patients. This includes the likely extent of weight loss, the expected benefits, the risks both during and after the surgery, and the long-term effects on nutrition and on quality of life.
This course will address the indications for bariatric surgery, the types of procedures currently in use, the specific benefits for the treatment of obesity-related diseases, and the short- and long-term risks. It will also briefly address other treatments for severe obesity, including medication and therapeutic lifestyle change.
National Health and Nutrition Examination Survey (NHANES) data illustrate how rapidly obesity has been increasing in the United States. NHANES II, covering 1976 through 1980, showed that 15% of adults 20 to 74 years of age were obese . NHANES III, with data from 1988 through 1994, found that 23% of adults in this age group were obese. The 2003–2004 survey found obesity in 33% of adults, while the 2005–2006 survey found obesity in 34% of adults. Data covering 2013 through 2014 indicate that 37.7% of U.S. adults are obese . While this is not a statistically significant increase over the previous two surveys, the prevalence of obesity exceeds the goal of 30.6% set by the U.S. Department of Health and Human Service's Healthy People 2020 .
Obesity is not evenly distributed among the population. According to statistics from the Centers for Disease Control and Prevention (CDC), adults 40 to 59 years of age are more likely to be obese than adults 20 to 30 years of age or adults 60 years of age or older, although the distribution varies somewhat when divided by gender and ethnic group . NHANES data indicate that the overall prevalence of obesity was greater for women (40.4%) than men (35.0%) in 2013–2014 . According to data from the 2012 Behavioral Risk Factor Surveillance System (BRFSS), the obesity prevalence ranged from 30.3% for men and women 20 to 39 years of age to 39.5% for men and women 40 to 59 years of age and 35.4% for men and women 60 years of age and older .
Some racial and ethnic differences in obesity rates exist. In 2013–2014, 57.2% of non-Hispanic black women were obese compared with 40.5% of all women, and the prevalence of obesity was higher among non-Hispanic black (48.5%), Hispanic (42.7%), and non-Hispanic white (37.1%) adults than among non-Hispanic Asian adults (12.7%) .
Cases of type 2 diabetes, which is strongly associated with obesity, have increased along with obesity prevalence. According to an analysis of data collected during 1995–2010 by the BRFSS, the age-adjusted prevalence of diagnosed diabetes increased in every state, the District of Columbia, and Puerto Rico, with the median prevalence for all geographic areas increasing from 4.5% to 8.2% . In 1995, the age-adjusted prevalence was ≥6% in only three states, DC, and Puerto Rico. In 2010, it was ≥6% in all areas. During 1995–2010, the overall median increase in age-adjusted prevalence of diabetes was 82.2% . According to data from the National Health Interview Survey, 5.6 million Americans had been diagnosed with diabetes in 1980 . By 2005, the number had risen to 16.3 million. Estimates from the CDC show that there were approximately 21 million people with a diagnosis of diabetes in 2014 and an additional 8.1 million unaware that they had the disease .
With the substantial increase in the number of obese Americans over the past several decades, the use of bariatric surgery has increased as well. According to a statistical report from the Agency for Healthcare Research and Quality (AHRQ), the annual number of bariatric surgeries in the United States increased from 13,386 to 121,055 between 1998 and 2004, a change of more than 800% . According to the American Society for Metabolic and Bariatric Surgery (ASMBS), the number of bariatric surgeries performed in the United States increased from 158,000 in 2011 to 179,000 in 2013, an increase of 15%, with the biggest jump occurring between 2011 and 2012 .
Weight loss and metabolic outcomes after bariatric surgery are of similar magnitude in men and women; however women continue to undergo bariatric surgery more often than men, comprising more than 80% of procedures [25,26]. Men also tend to wait longer and opt for the procedure only after their weight has led to serious health consequences. Most procedures are performed in adults 18 to 54 years of age, but the number of adults older than 55 years of age choosing bariatric surgery has increased greatly. The use of these procedures in adolescents is controversial and numbers remain small. The procedure rate per 100,000 adolescents increased from 0.8 in 2000 to 2.3 in 2003 but has not changed significantly since that time .
The AHRQ report estimates that inpatient costs of bariatric surgery are greater than $1.2 billion, with a per-procedure cost greater than $10,000 . Insurance coverage varies. Medicare covers common types of bariatric surgery for patients with body mass index (BMI) greater than 35 and at least one obesity-related comorbidity, if medical treatment for obesity has been unsuccessful. However, the surgery must be performed at a center approved by certification programs of the American College of Surgeons or the ASMBS . A list of approved centers is available at the Medicare website. Device manufacturers are lobbying the U.S. government and the health insurance industry to more fully cover bariatric surgery in order to provide access to the millions of obese Americans who might benefit from treatment and help save billions of dollars in healthcare costs. Some states require some level of coverage, but the requirements vary and often are not mandated for employers .
Bariatric surgery is a general term for surgical procedures that alter the digestive tract to promote weight loss. The surgery may reduce the size of the stomach or portion off a small area, reconfigure the small intestine, or comprise a combination of such alterations. Procedures that change the size of the stomach are called "restrictive." Those that reconfigure the intestine are "malabsorptive."
By reducing the area of stomach available to hold ingested food, restrictive surgeries decrease the amount of solid food that a person can comfortably eat and promote a sense of satiety. When the stomach outlet is reduced in diameter, these surgeries also slow the flow of ingested nutrients, helping patients to feel full longer. Malabsorptive surgeries reduce the area of the small intestine available to absorb nutrients.
Weight-loss surgeries most commonly used in the United States are the Roux-en-Y gastric bypass (RYGB) and the laparoscopic adjustable gastric band (LAGB). RYGB is a mixed restrictive/malabsorptive procedure, while LAGB is purely restrictive. Based on data from the University HealthSystem Consortium Clinical Database, gastric bypass made up 66% of bariatric surgeries performed at academic medical centers in 2007, while LAGB accounted for 23% . Certain other surgeries, previously common, have fallen out of favor due to high complication rates. They are described briefly in this course because patients who had these surgeries will still be seen in primary and specialty care. Many publications regarding bariatric surgery incorporate multiple procedures or variations on RYGB; as much as possible, the original terminology will be used when discussing each study.
The National Institutes of Health (NIH) first offered guidelines for bariatric surgery in 1991 . In their guidelines, the NIH stated that candidates for surgery were those patients with BMI greater than 40 or BMI greater than 35 if high-risk comorbid conditions, such as diabetes, were present. Surgery could also be considered in this group if obesity-related conditions interfered with daily life. In addition, patients must be well-informed, motivated, and able to participate in treatment and long-term follow-up. Patients also were expected to understand the risks of surgery and consider them acceptable .
In 2005, the American College of Physicians (ACP) published their own guidelines . They recommend considering surgery as an option for patients with BMI of 40 or greater who have obesity-related conditions, such as diabetes, impaired glucose tolerance, hypertension, hyperlipidemia, or obstructive sleep apnea. Patients should have tried and failed "an adequate exercise and diet program," with or without drug treatment . The ACP cautions that physicians should discuss long-term side effects with patients, including the potential for cholelithiasis or malabsorption and the possibility that repeat surgery may be needed.
In 2008, the American Association of Clinical Endocrinologists, the Obesity Society, and the ASMBS released guidelines for the perioperative care of the bariatric surgery patient . Their selection criteria include BMI greater than 40 if no comorbidities are present or greater than 35 if there is obesity-associated comorbidity. In addition, patients must have tried and failed non-surgical weight reduction and be willing and able to adhere to postoperative care. There also must be no current alcohol or drug abuse, no severe psychiatric illness that is uncontrolled, and no underlying disorder causing the obesity. Finally, patients must understand the risks, benefits, alternatives, necessary lifestyle changes, and expected outcomes. Since publication of these criteria, sufficient data were presented to the U.S. Food and Drug Administration (FDA) that led to the approval of more relaxed criteria (i.e., BMI less than 35 with an obesity-related comorbidity [mild obesity]) for LAGB. Researchers have demonstrated comparable safety and efficacy of LAGB between mildly obese and more severely obese patients .
Preoperative strategies vary among bariatric programs in the United States, including the controversial strategy of whether patients should lose weight prior to surgery. Studies have suggested that a preoperative weight loss of approximately 10% is associated with greater weight loss one year postoperatively, shorter length of hospital stay, and more rapid short-term postoperative weight loss [35,36]. However, no improvement has been seen in the risk of postoperative complications and in long-term, sustained postoperative weight loss . Another study found that insurance-mandated dietary counseling undertaken to produce preoperative weight loss led to no improvement in postoperative weight loss and was associated with increased patient dropout rates prior to gastric bypass surgery . The mandate reportedly does not consider that individuals who seek bariatric surgery typically report an extensive dieting history . The most important benefit of preoperative weight loss may be the observed reductions in liver volume and visceral fat. Loss of visceral fat reduces intra-abdominal pressure, which may in turn lead to improvements in urinary incontinence, gastroesophageal reflux, and systemic hypertension [33,40,41,42].
As a result of the evolving racial and immigration demographics in the United States, interaction with patients for whom English is not a native language is inevitable. Because patient understanding of the bariatric procedure, the associated risks, and the necessary lifestyle changes is such a vital aspect of identifying appropriate candidates for surgery, it is each practitioner's responsibility to ensure that information and instructions are explained in such a way that allows for patient understanding. When there is an obvious disconnect in the communication process between the practitioner and patient due to the patient's lack of proficiency in the English language, an interpreter is required. In this multicultural landscape, interpreters are a valuable resource to help bridge the communication and cultural gap between clients/patients and practitioners. Interpreters are more than passive agents who translate and transmit information back and forth from party to party. When they are enlisted and treated as part of the interdisciplinary clinical team, they serve as cultural brokers, who ultimately enhance the clinical encounter. In any case in which information regarding diagnostic procedures, treatment options and medication/treatment measures are being provided, the use of an interpreter should be considered.
The most common form of bariatric surgery involves the creation of a small proximal gastric pouch with a tight outlet and a Roux-en-Y configuration of the small bowel. The pouch is created by transecting the stomach a short distance below the esophagogastric junction. The gastric pouch holds approximately 30 mL, while a normal stomach holds approximately one liter. The small bowel is divided partway along the jejunum, and the distal portion is anastomosed to the gastric pouch. The proximal portion of small bowel, which remains attached to the stomach remnant, is then reconnected to the distal portion further along its length, so gastric acid, intrinsic factor, and pepsin will continue to flow and will mix with ingested food.
RYGB may be performed laparoscopically or open. Factors that affect this decision include the patient's body habitus, prior abdominal surgeries, and the skill of the surgeon . Patients with extremely high BMI may be better candidates for open rather than laparoscopic surgery. For the surgeon, laparoscopic gastric bypass is technically demanding and has a steep learning curve.
Gastric bypass works primarily by restricting food intake and promoting a sense of satiety with relatively small amounts of food. The usual form of the procedure bypasses a small enough portion of intestine that malabsorption of caloric nutrients is thought not to be a significant mechanism of weight loss, although the configuration does decrease absorption of certain vitamins and minerals [43,44]. Because the surgeon may, at times, choose to alter the surgery to promote more significant malabsorption, healthcare professionals who care for patients who have had bariatric surgery should obtain the details of the procedure whenever possible. A distal gastric bypass is a more malabsorptive procedure.
According to the ASMBS, there is no consensus on absolute contraindications to bariatric surgery . Individual risk should be evaluated and discussed with each patient. Surgery should not be offered to patients who cannot understand the risks and benefits or who are unable to commit to the lifestyle changes needed to maintain health after the procedure.
RYGB appears to produce more substantial weight loss than LAGB, although long-term studies suggest that weight loss may even out over time . There is some evidence that alterations in gut hormones, including peptide YY and glucagon-like peptide 1 (GLP-1), may lead to suppression of appetite and thus decreased food intake, supporting increased weight loss over purely restrictive procedures.
Because RYGB alters the configuration of the digestive tract, it changes the body's response to certain foods. A "dumping syndrome" may occur, particularly with the ingestion of foods with high sugar content. Within a short time after eating, patients with dumping syndrome experience lightheadedness, palpitations, flushing, and diarrhea. Dumping syndrome occurs in 70% or more of gastric bypass patients initially . In some, it resolves over time, but others have ongoing intolerance to certain foods. Some experts and patients feel that dumping syndrome is actually an advantage, because it discourages consumption of high-calorie, low-nutrient foods . Reversal of RYGB has been proven as a safe and effective way to treat dumping syndrome .
The first LAGB was approved in the United States in 2001. Earlier types of gastric bands included non-adjustable versions and bands placed using open surgery. The current version is designed to be placed laparoscopically.
The LAGB is a device that is placed around the stomach just below the esophagogastric junction, creating a pouch that holds only a few ounces. A piece of tubing connects the band to a subcutaneous infusion port, placed below the skin of the abdomen. Saline is used to inflate the band and adjust the diameter of the gastric pouch outlet .
Several weeks after the initial surgery, the first saline injection is given, usually about 0.5–1 mL. The "tightness" of the band may be tested using a barium swallow and fluoroscopy or more simply by making sure that sips of water are tolerated comfortably . Band tightness is titrated to achieve a safe rate of weight loss, about 1 to 2 pounds per week. The amount of saline needed varies from person to person.
After each adjustment, patients are generally advised to consume a liquid diet for a day or two, then soft foods for a day or two, before returning to their usual diet. Patients may notice that they are more aware of the restriction for the first few days after an adjustment.
The surgery involves no permanent alterations to the anatomy of the digestive tract. The band is removable, although it is generally intended to remain in place long-term.
Placement of a gastric band is not thought to interfere with the normal process of digestion. It simply slows the movement of food through the digestive system and, by causing discomfort when large amounts of food are eaten at once, helps to reduce intake.
Individual evaluation is essential to determining if a patient is a good candidate for LAGB. Contraindications to the use of an LAGB device include :
Crohn's disease or other inflammatory diseases of the digestive tract
A high risk of upper gastrointestinal (GI) bleeding
Abnormal anatomy of the digestive tract
Severe heart disease
Severe lung disease
Cirrhosis of the liver
Chronic steroid use or, in some cases, steroid use within 15 days of initial surgery
Addiction to alcohol and/or drugs
As with any bariatric surgery, patients who are not able or willing to alter their diet and lifestyle should not undergo gastric band placement .
Gastric banding appears to have a lower complication rate and a lower mortality rate than other forms of bariatric surgery. Because it does not alter normal digestive function, it does not directly precipitate anemia or vitamin deficiencies and does not cause a dumping syndrome. Time in the hospital is generally brief, and many patients return home the same day.
For most patients, surgically-induced weight loss involves a single surgical procedure. In some patients, however, extreme obesity or serious comorbidities preclude the use of the procedure that, in the surgeon's judgment, would provide the most effective weight loss. A surgeon may feel that a patient with a very high BMI and heart disease will have the best long-term result from RYGB. However, the risk-benefit ratio in such a patient may be better for a less invasive procedure, such as LAGB. In this case, the surgeon may opt to begin with band placement. After significant weight loss has been achieved, the patient's risk profile may become more favorable, allowing removal of the band and completion of the more definitive procedure.
Another first-stage procedure is the laparoscopic vertical sleeve gastrectomy, which reduces the size of the stomach by creating a tube-shaped passageway. The sleeve gastrectomy has gained popularity as a stand-alone procedure due to its efficacy for weight loss in short-term follow-up and its low complication rates. However, long-term results are not available and the indications for the procedure are still under evaluation [50,51,52,53]. The change to the stomach resulting from sleeve gastrectomy decreases the production of ghrelin, a gut hormone that stimulates appetite and influences body weight . In contrast, diet-induced weight loss causes increased concentrations of ghrelin, which drives appetite and promotes weight regain .
Although not yet available in the United States, a gastric balloon has also been used as a temporary, first-stage option . The balloon, placed endoscopically, creates a sensation of fullness by simply taking up space in the stomach.
Many other procedures have been used in bariatric surgery, but for the most part they have fallen out of favor. These include jejunoileal bypass, vertical banded gastroplasty (VBG), and biliopancreatic diversion (BPD). However, research on new techniques and devices is being conducted, with the goal of reducing complications while maximizing weight loss.
Jejunoileal bypass, used in the 1960s and 1970s, was a purely malabsorptive procedure, bypassing most of the small intestine without altering the size of the stomach . Weight loss was substantial, but complications included liver disease and liver failure, severe vitamin deficiency, electrolyte imbalances, malnutrition, osteomalacia, cholelithiasis due to reduced bile salts, and excess oxalate absorption leading to kidney stones [33,58]. This procedure has essentially been abandoned.
Vertical banded gastroplasty involves the partitioning of the stomach, with the creation of a small pouch with a tight stoma. It was a common procedure during the 1980s, but long-term weight loss was unsatisfactory . In addition, the use of mesh or silicone tubing to reinforce the small opening led to problems with localized infection and erosion of foreign material into the stomach. Some patients developed vomiting due to intolerance of the gastric constriction.
Biliopancreatic diversion is another malabsorptive procedure, now used less often than RYGB and LAGB . In this surgery, the intestine is configured similarly to the RYGB, but a larger segment of intestine is bypassed and pancreatic enzymes are diverted so they enter directly into the ileum rather than the duodenum. Absorption of fats is particularly affected. Removal of the lower half of the stomach reduces the production of gastrin, thus decreasing the amount of stomach acid released. In a variant of BPD called duodenal switch, the proximal portion of the duodenum, which is more resistant to stomach acid than the small intestine, remains connected to the stomach. Duodenal switch maintains the malabsorptive component of BPD but adds a more significant restrictive component as well. Adverse effects of BPD and duodenal switch include nutritional deficiencies and foul-smelling flatus and diarrhea related to malabsorption of fat .
Other procedures and devices are in development and/or undergoing evaluation for use in the weight-loss setting. One such procedure involves use of an implantable gastric stimulation device that creates a sensation of fullness in the patient by stimulating the stomach with small electrodes. Transoral gastroplasty (TOGA) surgery is an incision-free, restrictive procedure using a set of flexible staplers that are introduced through the mouth and esophagus to create a sleeve in the stomach. The TOGA device is considered investigational in the United States and is available only through clinical trials for eligible individuals [43,60,61,62]. Another relatively new restrictive procedure that has demonstrated encouraging results is transoral gastric volume reduction (TGVR) [63,64,65]. TGVR encompasses several techniques to reduce gastric volume and absorption without the need for open surgery, including the use of sutures, staples, implanted devices, or endoluminal barriers . An endoluminal barrier is a gastrointestinal liner designed to mimic the effects of gastric bypass surgery without the risks. It is undergoing clinical trials and investigational studies [52,66].
The mortality rate of bariatric surgery is often related as "less than 1%." In fact, mortality rates differ according to procedure, patient characteristics, and the surgeon's skill.
According to data from the Healthcare Cost and Utilization Project, reported by the AHRQ, between 1998 and 2004 the national inpatient death rate associated with bariatric surgery declined from 0.89% to 0.19% . Death rates differed by gender, with the rate for men being 2.8 times higher than the rate for women. This gap has narrowed, down from a six-fold increased risk in men in 1998.
In 2007, Buchwald and colleagues conducted a meta-analysis of mortality data using studies published between 1990 and 2006 . Based on a total of 361 studies including 478 treatment arms and 85,048 patients, they found an overall mortality rate of 0.28% within the first 30 days and 0.35% between 31 days and two years. For gastric bypass, 30-day mortality was 0.44% for open procedures and 0.16% for laparoscopic procedures. Mortality from 31 days to two years was 0.69% and 0.09%, respectively. For gastric banding, open procedures had a short-term mortality rate of 0.18%, while the short-term mortality for laparoscopic procedures was 0.06%. The longer-term mortality rates were statistically 0.00% for both groups. For the most part, this analysis found that mortality trended downward with more recent studies, and smaller studies had higher mortality rates than larger ones. Mortality was highest in observational studies (0.7%) compared to other study designs (0.07% to 0.30%) .
Nguyen and colleagues conducted an audit of bariatric surgery cases at 29 institutions participating in the University HealthSystem Consortium Bariatric Surgery Benchmarking Project . For each institution, 40 consecutive cases were examined; a total of 1,144 cases met inclusion criteria, which was age older than 17 years and younger than 65 years, BMI of 35–70, and no previous bariatric surgery. Procedures were primarily gastric bypass (91.7%), with smaller numbers of gastroplasty or gastric banding (8.2%) and BPD (0.1%). For gastric bypass, with about three-fourths of the procedures done laparoscopically, 30-day mortality was 0.4%. Restrictive procedures had a 30-day mortality of 0%, with 92% of procedures done laparoscopically.
Other studies have shown that increased physician experience and higher case volumes are associated with lower mortality. For example, lower mortality rates have been reported at hospitals doing more than 100 bariatric surgeries annually compared to hospitals with lower numbers. Length of stay, morbidity, and costs were also lower at the high-volume institutions . Concerns regarding the safety and uneven quality of bariatric surgeries performed across hospitals prompted the American College of Surgeons (ACS) and the ASMBS to implement an accreditation program for hospitals called "centers of excellence." The general guidelines to receive accreditation vary between programs but typically include a minimum volume of procedures, availability of resources for morbidly obese patients, and submission of outcomes data to a central registry [69,70]. The ASMBS and ACS also partnered with the Society for American Gastrointestinal and Endoscopic Surgeons to establish credentialing guidelines for bariatric surgeons to ensure that surgeons maintain a certain skill level and are prepared for potential complications during bariatric surgery .
Bariatric surgery is widely considered a safe procedure, but complications do occur. Possible early complications of RYGB include leaks at the anastomosis sites, GI hemorrhage, and the usual surgical risks of pulmonary embolism and infection . Early problems with LAGB may include gastric or bowel perforation, slippage of the band, and obstruction due to edema . During recovery after surgery, patients may experience reflux or regurgitation, nausea, diarrhea, and constipation.
Following both RYGB and LAGB, patients may experience vomiting related to the small size of the stomach pouch. This is expected to resolve as healing occurs and as patients learn how much food they are able to tolerate. Persistent vomiting may signal stomal stenosis, a too-restrictive band, or other problems requiring intervention.
The precise incidence of serious complications with RYGB and LAGB is unclear. A review of 128 studies (primarily case series) conducted for the AHRQ revealed that surgical complications, including anastomotic leaks, bleeding, and reoperations, occurred in 18.7% of RYGB cases and 13.2% of LAGB cases . Medical complications, including cardiac events, stroke, and severe hypertension, were seen in 4.8% and 0.7%, respectively. Gastrointestinal symptoms following surgery, including reflux, dysphagia, and dumping syndrome, occurred in 16.9% of RYGB patients and 7% of LAGB patients. However, no firm conclusions were able to be drawn from these numbers because the severity of included complications is unknown.
Later complications of RYGB include incisional or internal hernia, stenosis at the anastomosis sites, bowel obstruction, ulcers near the stomach pouch outlet, and vitamin or mineral deficiencies [60,73]. With LAGB, patients may experience problems related to migration of a portion of the stomach above the band, erosion of the band into the stomach, infection at the port site, or disconnection of the tubing leading to the port [60,73]. Incisional hernia may also occur .
Some adverse effects are not technically surgical complications, but occur as a result of rapid weight loss. Cholelithiasis is a common result of rapid weight loss and is frequently seen in bariatric surgery patients . Estimates of symptomatic cholelithiasis after RYGB, for example, range from 3% to 28% in various studies .
During the first several months after surgery, if weight loss is successful, patients may experience discomfort due to hypometabolism. They may experience fatigue, cold intolerance, and hair loss, all of which are expected to resolve as weight loss stabilizes .
After any bariatric surgery procedure, patients must change their eating habits significantly. Shortly after surgery, patients will usually be able to begin a liquid diet. Depending on the specific instructions from the surgeon, patients will slowly advance, over a matter of weeks, from clear to full liquids, then to pureed foods, and eventually to solids.
Small portions, chewed thoroughly, are essential for safety, comfort, and weight loss. Taking in too much food at once can lead to vomiting as the capacity of the gastric pouch is exceeded . Food that has not been thoroughly chewed can become lodged in the stomach pouch outlet.
Adequate protein intake is important both to reduce hunger between meals and to ward off malnutrition. Foods high in sugar can cause dumping syndrome following RYGB and should therefore be eaten in moderation or avoided altogether.
Patients should also pay special attention to liquid intake. Liquids should be sipped slowly. With LAGB, combining solids and liquids can speed transit of food from the upper pouch through the digestive system, so intake should be separated by approximately 30 minutes. After RYGB, consuming liquids and solids together may trigger dumping syndrome .
Patients should generally be advised to take a daily multivitamin-mineral supplement containing iron, in addition to supplemental calcium and a B-complex preparation . Other supplements may also be required. Nutritional concerns following bariatric surgery will be discussed in greater detail later in this course.
Patients will generally be instructed to begin exercising shortly after surgery. With LAGB placement, patients can generally resume light exercise soon after returning home and progress to more vigorous exercise after a few weeks. After laparoscopic RYGB, patients can begin taking short walks early after surgery, with the surgeon's approval, and usually begin or resume heavier exercise after about six weeks. Open surgery requires a longer healing time before exercise can be started or resumed.
In a review of the literature, researchers examined published studies and case series of pregnancy following bariatric surgery . They concluded that, overall, pregnancy after RYGB or LAGB appeared to be safe and bariatric surgery patients seem to have lower risk of several obesity-related gestational complications [76,77]. However, they noted that patients in published studies often received careful prenatal care, including nutritional monitoring and LAGB adjustment, and that community practitioners should take care to provide a similar level of monitoring and intervention as needed. They also observed that surgery-related complications, such as internal hernia, do occasionally occur, although rates appear to be low.
The current recommendation from the American College of Obstetricians and Gynecologists (ACOG) is that women should delay pregnancy for 12 to 24 months after bariatric surgery to ensure that gestation does not occur during the rapid weight-loss phase [78,79]. However, the opportune timing of pregnancy after surgery is unknown. The ACOG also strongly recommends preconception assessment and counseling and education regarding possible complications. Prior to attempting pregnancy, obese patients should be encouraged to undertake a weight-reduction program that includes diet, exercise, and behavior modification. Evaluation for nutritional deficiencies and the need for vitamin supplementation is also recommended .
Weight loss after bariatric surgery is usually most rapid in the first year. It may be fastest in the first few months, when caloric restriction is greatest. Weight loss is expected to slow at about six to nine months, and maximal total loss generally occurs at around 12 to 18 months .
With gastric bypass, about 80% of patients can be expected to achieve 60% to 80% excess weight loss during the first year, with later stabilization at about 50% to 60% . In a meta-analysis of reports on various bariatric procedures, Buchwald and colleagues concluded that excess weight loss averaged 61.2% two years after surgery . Weight loss with specific surgeries was 47.5% for gastric banding, including both adjustable and non-adjustable versions; 61.6% for gastric bypass, primarily variants of RYGB; and 70.1% for BPD or duodenal switch.
In a meta-analysis based on controlled trials comparing procedures, researchers reported actual weight lost instead of percentages and found that patients achieved weight loss of 30 kg (about 66 pounds) or more at 36 months with RYGB, LAGB, and VBG . Of the three procedures, RYGB appeared to provide the most substantial weight loss.
In 2007, Angrisani and colleagues published a randomized controlled trial comparing laparoscopic RYGB to LAGB. In terms of weight loss, RYGB had better outcomes at five years, with significantly greater weight loss and fewer patients failing to achieve BMI less than 35. However, more serious surgical complications occurred in the RYGB patients . Several case series and retrospective studies support this pattern, although the data on complications are not entirely consistent .
A 2008 review of studies comparing RYGB and LAGB, conducted by Tice and colleagues, concluded that weight loss, at least in the short term, was better with RYGB . Perioperative morbidity appeared to be higher with RYGB, with long-term complications more frequent after LAGB. However, the review authors note that problems with data reporting, including missing details about complications, make it difficult to truly weigh the tradeoffs.
A 2011 review of studies comparing three laparoscopic procedures in bariatric surgery—sleeve gastrectomy, RYGB, and LAGB—found RYGB and sleeve gastrectomy to be more effective at achieving weight loss than LAGB. However, LAGB was found to be safer with frequent (but less severe) long-term complications. All three procedures achieved similar resolution of obesity-related comorbidities .
The sustainability of weight loss after bariatric surgery is thought to be good, although lifelong data are not yet available. Evidence is available from two large studies: the Swedish Obese Subjects (SOS) study, which has reached 20 years of follow-up, and a Canadian study reporting on outcomes after up to 16 years. In the SOS study, obese patients who underwent bariatric surgery were compared to matched controls who received conventional treatment for obesity [8,84]. A total of 4,047 subjects were enrolled, and by the time of the first analysis, 1,703 had been followed for at least 10 years. Surgical treatments were gastric banding (fixed or adjustable), VBG, or gastric bypass. Weight loss was maximal after one year in the surgical groups. Gastric bypass produced the most weight loss, followed by VBG, and then banding. At two years, some weight regain was apparent, with weight loss among surgery patients averaging 23%. At 10 years, weight regain had continued and surgery patients were only 16% below their starting weight, with gastric bypass patients still having the largest weight loss. At 20 years, surgery patients were 18% below their starting weight . Meanwhile, however, the comparison group had a 10-year weight gain of 1% and a 20-year weight loss of 1% . There were 129 deaths in the control group compared with 101 in the surgery group. The unadjusted overall mortality was reduced by 23.7% in the surgery group; gender-, age-, and risk factor-adjusted mortality was reduced by 30.7% .
The assessment of weight loss reported in the Canadian study was part of a study that also compared morbidity and mortality among surgery patients and controls . This study included 1,035 bariatric surgery patients treated for morbid obesity at the McGill University Health Centre between 1986 and 2002. Approximately 81% of the procedures were RYGB and 19% were VBG. With a mean overall follow-up of 5.3 years, excess weight loss was 43.4% to 90.8%. Weight loss was significantly higher after RYGB than VBG. Many patients were followed to 10 years and some to 16 years, with weight loss sustained at close to maximal levels. Data on weight loss among the control population was not available. A systematic review examined medium- and long-term weight loss after RYGB, RYGB variants (e.g., long-limb bypass), BPD and duodenal switch, and LAGB . Overall, weight loss appeared to be durable to at least 10 years. However, weight regain was most apparent with RYGB, with excess weight loss declining from nearly 70% at two years to about 50% at 10 years. LAGB showed gradual progression of weight loss for three years, followed by stabilization. At years 1 and 2, pooled data showed that mean excess weight loss was superior with RYGB over LAGB, with a statistically significant difference. At years 3 through 8, the difference was no longer significant. The authors note that there was limited data on the number of patients lost to follow-up and on the number of patients measured at each data point.
A study published in 2010 followed 442 case-matched patients with a BMI of less than 50 who underwent either RYGB or gastric banding . Outcomes measured were operative morbidity, weight loss, residual BMI, quality of life, food tolerance, lipid profile, and long-term morbidity. Early morbidity was higher after RYGB than after gastric banding; overall morbidity was similar. In patients who underwent RYGB, a more rapid weight loss was reported, and maximal weight loss was greater and more sustained. A greater number of long-term complications and need for repeat procedures were reported in the gastric banding group. Comorbidities improved more significantly in the RYGB group .
There is some evidence that weight loss due to bariatric surgery may vary not just by procedure but also by setting and patient population. A retrospective review of 59 patients who underwent RYGB between 1997 and 2002 at the Veterans Administration-Greater Los Angeles Health Care System found peak excess weight loss to be 52%, substantially lower than that reported in other studies . However, maintenance of weight loss was good. The percentage of patients who achieved more than 50% excess weight loss was 54% at 12 months, 58% at two years, 47% at three years, and 44% at four years. Another retrospective review analyzed postoperative comorbidities and percent of excess weight loss in a group of 70 U.S. veterans who underwent laparoscopic RGYB between 2003 and 2006 . Average preoperative weight and BMI were 310 pounds and 46, respectively. The incidence of major complications was 1.4%; no mortalities were reported. Excess weight loss was 61% at one year, 53% at three years, and 59% at five years (56% at mean follow-up of 39 months).
A small number of patients will not have large amounts of weight loss after surgery. Precise numbers of "failures" are not known, in part because there is no set cut-off for "acceptable" or "successful" weight loss. Because suboptimal weight loss and/or weight regain are not uncommon, considerable attention is being given to identifying reliable outcome predictors. Researchers have just begun to identify the complex contributing factors that influence postoperative outcomes, including preoperative psychological status (e.g., mood disorders, anxiety disorders), patient expectations regarding anticipated weight reductions, and concurrent unhealthy behaviors (e.g., binge eating, emotional eating, night eating). Understanding these factors is expected to contribute to improved weight-loss management and prevention of weight regain. The long-term success of bariatric surgery relies on patients' ability to make sustained lifestyle changes [91,92,93,94,95,96].
A paradigm shift has expanded the role of bariatric surgery from a focus on the effects on obesity to include the effects on metabolic disorders, specifically type 2 diabetes. This shift is reflected in a position statement issued by the International Diabetes Federation (IDF) in 2011 . In this statement, the IDF supports bariatric surgery as a treatment option for select patients with type 2 diabetes. This position is endorsed by the American Association of Clinical Endocrinologists in their 2011 guidelines for comprehensive diabetes care [97,98,99].
The connection between type 2 diabetes and obesity has become increasingly clear as the prevalence of both conditions has risen. Exercise and weight loss are now established as ways to reduce the risk of developing type 2 diabetes. The Look AHEAD trial, designed to evaluate the effects of weight loss on cardiovascular risk in patients with diabetes, has published early data demonstrating improved diabetes control with a lifestyle intervention designed to promote weight loss . Using portion control, a home-based exercise program, and optional weight-loss medication, patients in this study lost an average of 8.6% of initial weight. At present, however, some of the strongest data linking weight loss to improvement in diabetes comes from studies of bariatric surgery. Reviews and meta-analyses of publications concerning bariatric surgery have consistently found improvement or resolution of diabetes in the majority of patients.
The AHRQ evidence report related that, in published bariatric surgery case series, diabetes improved or resolved in 69% to 100% of cases . In the meta-analysis by Buchwald and colleagues, among studies that reported resolution of diabetes, 76.8% of patients had complete resolution . In studies that also reported improvement, 86.0% had either resolution or improvement. A 2007 review found that diabetes resolved in more than 75% of bariatric surgery patients .
In the SOS study, at two years of follow-up, diabetes had resolved in 21% of conventionally treated patients and 72% of surgery patients. Among those who had been followed for 10 years, the recovery rate was 13% for conventional treatment compared to 36% for surgery .
In 2008, researchers published data from a randomized controlled trial comparing lifestyle change, including the option of medication to treat obesity, to LAGB in patients with type 2 diabetes . Out of 60 patients enrolled, 55 were followed to two years. Starting BMI was between 30 and 40, and diabetes diagnosis was recent, having been made within the past two years. The surgery group lost 62.5% of excess body weight, and 73% experienced remission of type 2 diabetes. In the non-surgical group, excess weight loss was 4.3% and diabetes remission was 13%. Remission of diabetes correlated with weight loss and also with lower hemoglobin A1c (HbA1c) levels at baseline.
The American Diabetes Association (ADA) previously defined remission of type 2 diabetes as when a patient has a normal fasting blood glucose level or HbA1c less than 6% without the aid of hypoglycemic medications . The ADA has revised this definition to include HbA1c less than 6% and fasting glucose levels of less than 5–6 mmol/L without medication at least 1 year following bariatric surgery. In a report published in 2012, researchers used the revised ADA definition and data from 1,006 patients, 209 of whom had type 2 diabetes at the time of gastric surgery. Median follow-up was 23 months. Based on the new ADA standard, remission rates were 40.6% after gastric bypass, 26% after sleeve gastrectomy, and 7% after gastric banding. On average, patients remained obese after surgery, and oral hypoglycemic medications were still used by 29.4% of gastric bypass patients, 63% of sleeve gastrectomy patients, and 83% of gastric banding patients [97,102].
Some studies have attempted to compare the effects of different bariatric procedures on diabetes. While weight loss consistently appears to be greater with RYGB than with LAGB, at least in the initial years following surgery, the long-term impact on diabetes is less clear. Parikh and colleagues have reported a case series of 282 patients with diabetes who underwent bariatric surgery at an academic hospital in New York . Two hundred and eighteen patients had LAGB, 53 had RYGB, and 11 had BPD/duodenal switch. Percent excess weight loss was significantly higher with BPD/duodenal switch and RYGB than with LAGB. However, the differences between groups with regard to postoperative use of hypoglycemic medications or insulin were not statistically significant.
In a series reported by Kim and colleagues, 232 patients undergoing gastric bypass were compared to 160 patients undergoing LAGB . In each group, about 20% of patients had diabetes. While excess weight loss was greater with gastric bypass, improvement or resolution of diabetes was similar: 72.1% in the gastric bypass group and 77.1% with LAGB, a non-significant difference.
In other studies, diabetes resolution has proven to be better with gastric bypass than with LAGB. The meta-analysis by Buchwald and colleagues found a gradation of effects on the resolution of diabetes: 98.9% for BPD or duodenal switch, 83.7% for gastric bypass, 71.6% for gastroplasty, and 47.9% for gastric banding . Later, Cottam and colleagues reported a matched-pair study comparing RYGB and LAGB and found that, in addition to more substantial weight loss in the gastric bypass group, resolution of diabetes was greater (78%) compared to the gastric banding group (50%) . In a prospective study of surgery in 106 super-obese patients (BMI >50), all patients with diabetes who underwent gastric bypass had normalization of blood glucose, while normalization occurred in only 40% of those treated with LAGB .
Although weight loss is clearly an important element in the improvement or resolution of type 2 diabetes, there has been much attention to the possibility that hormonal mechanisms unrelated to weight loss may have an impact as well. Investigations into this possibility have been spurred by the fact that many patients are able to discontinue their diabetes medications after undergoing RYGB, before any significant weight loss occurs.
Early normalization of blood glucose is occasionally seen in LAGB patients as well as in RYGB patients, suggesting that simple caloric restriction may play a significant role. However, there is some evidence that malabsorptive surgery increases both beta-cell sensitivity to glucose and peripheral insulin sensitivity . The diversion of nutrients away from the normal digestive pathway and the release of partially digested food into the distal small intestine appear to cause alterations in incretin signals to the pancreatic islets . In addition, changes in gut hormones may influence appetite and other responses to food . However, the interplay of these hormones and their influence on glucose metabolism is still being investigated. For example, GLP-1 has often been implicated in the improvements in glucose metabolism, but study measures of GLP-1 do not indicate that the hormone is critical in the improvement of glucose homeostasis after gastric bypass .
While malabsorptive procedures may have additional mechanisms of action against diabetes, similar changes in gut hormones do not occur with purely restrictive procedures . The reduction in diabetes associated with LAGB appears to be due to weight loss alone.
Multiple studies of bariatric surgery have reported significant declines in blood pressure at follow-up, although the role of bariatric surgery in preventing hypertension is less clear [8,112]. There may be a relationship between the length of pre-existing hypertension preoperatively and the likelihood for resolution following bariatric surgery .
In the SOS study, the incidence of hypertension was the same in both the treatment and the control groups at two and 10 years of follow-up . Recovery from hypertension, however, was significantly higher in the surgery group. At two years, 21% of controls no longer had hypertension, compared to 34% of surgery patients. Among patients followed to 10 years, 11% of previously hypertensive controls were normotensive, while recovery was 19% in the surgery group.
Studies with this length of follow-up are uncommon, but some additional evidence is available on blood pressure several years after surgery. White and colleagues used data from a single surgeon's gastric bypass cases (variations on RYGB), collected over 14 years, to examine outcomes including the resolution of hypertension . With a median follow-up of just over four years, 62% of previously hypertensive patients had normal blood pressure and 25% showed improvement.
Shorter-term studies have also found resolution of hypertension to be common after bariatric surgery. Ahmed and colleagues conducted follow-up with 100 patients for one year after RYGB to evaluate changes in blood pressure . By the end of one year, both the percentage of patients who were hypertensive and the number of patients taking medication for hypertension had decreased substantially. At baseline, 53 patients were on medication, with a decline to 15 at one year. Decreases in blood pressure occurred rapidly, beginning in the first week for some patients.
Changes in lipids are also widely seen in follow-up studies of bariatric surgery patients, although long-term data are somewhat mixed . In the SOS cohort, rates of recovery from hypertriglyceridemia and from low high-density lipoprotein (HDL) were better in surgery patients than in the control group at both two and 10 years of follow-up. Recovery from hypercholesterolemia, on the other hand, was not statistically different in surgical patients compared to controls at either time point. The incidence of hypercholesterolemia was similar as well.
Shorter-term evaluations of LAGB and gastric bypass have found significant improvements in low-density lipoprotein (LDL), HDL, and total cholesterol, generally at 12 months after surgery but with some studies having follow-up to four or five years [115,116,117,118,119,120,121]. The meta-analysis by Buchwald and colleagues, which included studies having at least 30 days of follow-up, concluded that hyperlipidemia typically improved in at least 70% of patients . Improvements were greatest with BPD, duodenal switch, and gastric bypass.
In addition to individual cardiovascular risk factors, metabolic syndrome has been shown to improve or resolve in many patients following weight loss surgery [11,12]. Metabolic syndrome is a constellation of cardiovascular risk factors, including obesity, hypertension, dyslipidemia, and insulin resistance. A retrospective study examined data from patients with metabolic syndrome who were evaluated for bariatric surgery at the Mayo Clinic's Rochester site between 1990 and 2003. One hundred eighty patients underwent RYGB, and 157 were assessed in a weight-loss program but did not have surgery . Patients were followed for a mean of 3.4 years. Before the procedure, 87% of the patients in the surgery group had metabolic syndrome. This number decreased to 29% after surgery. In the non-surgical group, metabolic syndrome was present in 85% at baseline and 75% at follow-up. The authors concluded that weight loss was largely responsible for metabolic syndrome resolution, and that the number-needed-to-treat to resolve one case was 2.1.
Other case series and observational studies have shown similar results. Gasteyger and colleagues followed 36 obese women, 24 to 52 years of age, with a mean BMI of 43.8 for 24 months after LAGB . The proportion of patients with metabolic syndrome declined from 58% at baseline to 25% at one year and 3% at 24 months. Another series with 31 female patients found a reduction from 89% with metabolic syndrome before LAGB to 15% at one year after surgery .
Several studies have attempted to assess changes in cardiac risk following bariatric surgery. Most have simply calculated risk using the Framingham score or a similar model. However, at least one study has compared predicted risk with actual cardiovascular events.
Studies of predicted risk have consistently found that bariatric surgery is beneficial in lowering scores. In 2008, Batsis and colleagues published a review of studies that provided numeric data about cardiovascular risk factors with follow-up of at least one year . The studies, conducted in the United States, Italy, Mexico, New Zealand, and Sweden between 1996 and 2004, included LAGB, non-adjustable gastric banding, RYGB, and VBG in a total of more than 3,000 patients. The researchers used Framingham risk and a score based on the German Prospective Cardiovascular Munster Heart Study (PROCAM), both of which incorporate multiple individual risk factors. When studies did not report certain factors, values were imputed using the risk models' original data. Consistently, and with multiple ways of examining the data, cardiovascular risk was found to decline after surgery. Standardizing patients' ages produced an even stronger apparent benefit. When control groups were used, risk was consistently lower in the surgical groups.
The two studies with the longest follow-up included in the review were the SOS study and a study by Batsis and colleagues comparing a cohort of surgical patients with non-operative patients from the same database. The Batsis study used data from the Mayo Clinic Nutrition Center in Rochester, Minnesota, from 1990 to 2003. It involved 197 consecutive patients treated with bariatric surgery and 163 patients evaluated in a weight-reduction program who did not have surgery . Patients had class II or III obesity, defined as a BMI of 35 or more. Patients were treated with RYGB, with mean follow-up of 3.3 years. Based on risk data from NHANES I and the NHANES I Epidemiological Follow-up Study, the authors found that, in the operative group, the 10-year risk for cardiovascular events was 37% at baseline and 18% at follow-up. In the control group, risk remained unchanged at 30%. The number needed to treat to avoid 1 cardiovascular event was calculated to be 16. Using Framingham risk scores, risk fell from 7.0% to 3.5% in the surgery group and from 7.1% to 6.5% in the control group .
The SOS study did not directly report changes in overall cardiovascular risk. However, calculations by Batsis and colleagues based on the reported data showed that risk scores declined after two years of follow-up. After 10 years, cardiovascular risk had risen, but risk in the surgical group remained numerically lower than in the non-surgical controls. Statistical significance was not reported .
A post hoc analysis of the SOS study, conducted after nearly 15 years of follow-up, has shown that bariatric surgery led to a 30% reduction in the incidence of cardiovascular events in obese patients compared with non-operative patients and an almost 50% reduction in cardiovascular deaths . Baseline insulin concentration, rather than BMI at baseline or post-surgery weight loss, was the strongest predictor of future cardiovascular benefit.
Other publications, including several case series with RYGB patients, further support a decrease in estimated risk [124,125,126]. To determine the relationship between risk scores and actual cardiovascular outcomes, one group of researchers followed patients for five years after surgery. They calculated Framingham risk and then compared it to actual coronary heart disease events in 500 patients without prior cardiovascular disease who had undergone gastric bypass . These patients lost 46.7% to 90.7% of excess body weight at one year after surgery and showed improvement in risk factors, including diabetes. The 10-year Framingham risk of cardiac events declined from 5.4% to 2.7%, with similar changes in subgroups based on diabetes status and gender. At five years after surgery, the actual occurrence of coronary heart disease events was 1%.
In a 2008 report, Kligman and colleagues used Framingham risk score to demonstrate reduced 10-year cardiovascular risk at one year after surgery in 101 consecutive patients who underwent RYGB . Systolic blood pressure fell by 14%, with a reduction in diastolic pressure of 12%. Total cholesterol was 202 at baseline and 165 at follow-up, a reduction of 18%. LDL decreased 18%, from 118 to 97; HDL increased 14%, from 45 to 51. All of these changes were statistically significant. Ten-year risk fell by more than half.
In 2010, researchers conducted a systemic review of published literature to determine the impact of bariatric surgery on cardiovascular risk factors and mortality . The review included reported outcomes following bariatric surgery from 1950 to 2010 and included 52 studies involving 16,867 patients. The baseline prevalence of hypertension, diabetes, and dyslipidemia was 49%, 28%, and 46%, respectively. Mean follow-up was 34 months. Most studies reported significant decreases in the postoperative prevalence of cardiovascular risk factors. A 40% relative risk reduction for 1-year coronary heart disease risk was observed, as determined by the Framingham risk score .
Follow-up studies have noted improvements in many other obesity-related conditions. In various cohorts and case series, patients have been observed to have improvements in or resolution of conditions including nonalcoholic fatty liver disease, polycystic ovarian syndrome, venous stasis disease, obstructive sleep apnea, gastroesophageal reflux disease, and degenerative joint disease . There is also some evidence for weight loss leading to improvement in depression, resolution of migraine, and resolution of or improvement in asthma. Patients may also experience improvement in urinary incontinence, pseudotumor cerebri, and hypoventilation .
As discussed, in the short term there is a small but definite mortality risk associated with bariatric surgery. However, long-term mortality data suggest that, compared to obese controls, patients who choose surgery experience a reduced risk of premature death. Data from the SOS study show that, with an average of 10.9 years of follow-up, there were 129 deaths in the control group and 101 deaths in the surgery group. The unadjusted overall hazard ratio was 0.76 in the surgery group . A review of data from the SOS study at 20 years follow-up found a long-term reduction in overall mortality as well as decreased incidences of diabetes, myocardial infarction, stroke, and cancer with bariatric surgery compared with usual care .
Similar benefit was noted in a retrospective cohort study that compared mortality among 9,949 gastric bypass patients and 9,628 severely obese controls . Matching for age, sex, and BMI was achieved in 7,925 of each group, and the mean follow-up was 7.1 years. Adjusted long-term mortality from any cause decreased by 40% in the surgery group compared to the controls, with 37.6 and 57.1 deaths, respectively, per 10,000 person-years. Cause-specific mortality in the surgery group decreased by 56% for coronary artery disease, by 92% for diabetes, and by 60% for cancer. Rates of death not caused by disease, such as accidents and suicide, were 58% higher in the surgery group than in the control group.
In addition to the long-term benefits of bariatric surgery, long-term complications should also be considered. RYGB makes permanent changes to the anatomy of the stomach and small intestine. LAGB, while designed to be removable, is intended to be used as a long-term treatment. In each case, the changes in dietary habits that should be made following surgery can put patients at risk for nutritional deficiencies, and the Roux-en-Y configuration raises particular concerns about adequate absorption of certain vitamins and minerals. Intolerance to certain foods, particularly meats, occurs in many patients after bariatric surgery and can lead to restricted dietary choices. Management of long-term needs can be a challenge, as patients do not always keep to recommended follow-up plans. The Endocrine Society recommends that an accredited, integrated medical support team provide patients with dietary instruction and behavior modification postoperatively and during long-term follow-up .
Vitamin and mineral deficiencies may occur after any bariatric procedure if the patient's diet does not supply adequate nutrition. Due to the altered configuration of the small intestine, patients who undergo RYGB and other surgeries with a malabsorptive element are particularly at risk of specific deficiencies. Folate, thiamine, riboflavin, niacin, pyridoxine, vitamin C, and copper are primarily absorbed in the duodenum and jejunum, and iron is primarily absorbed in the duodenum . After RYGB, ingested food does not pass through the duodenum and bypasses a portion of jejunum as well.
Anemia is a common problem following RYGB. Iron deficiency occurs in as many as 49% of patients following this procedure . In addition to direct malabsorption due to lack of contact with the duodenum, low or absent secretion of gastric acid decreases conversion of iron to its absorbable form. Overall decrease in food intake, combined with a common intolerance of red meat, may also contribute to deficiency . Giving iron with vitamin C can help to provide the acidic environment needed for absorption .
Anemia may also be due to deficiencies in vitamin B12, seen in an estimated 35% of RYGB patients . Although vitamin B12 is absorbed primarily in the ileum, which is not bypassed by the RYGB procedure, decreased gastric acid, decreased exposure to intrinsic factor, and other changes in the digestive process may all contribute to malabsorption . The ASMBS notes that vitamin B12 deficiency may be present in the general population and preoperative levels in severely obese patients are not well-established, making it prudent to screen for low levels before surgery . This deficiency appears to be less common after LAGB and other procedures that either leave the stomach intact or cause less restriction than RYGB . Additional contributors to anemia may include deficiencies in copper, folate, and other vitamins absorbed in the upper portion of the small intestine .
Folate deficiency appears to be particularly common. Prevalence after RYGB ranges from 6% to 65%, depending on the study . In addition to reduced absorption, low levels of vitamin B12 may contribute to low folate levels. However, the actual role of surgery in causing folate deficiency is not clear, given that inadequate intake is not rare in the general population. One study found deficiency in 56% of pre-operative bariatric surgery patients . Folate deficiency has also been seen following LAGB.
Symptomatic thiamine deficiency after bariatric surgery is not usual, but cases of Wernicke-Korsakoff syndrome, a degenerative brain disorder, after both malabsorptive and restrictive procedures have appeared in the literature . Patients who have unresolved nausea and vomiting may be particularly at risk. Case reports of beriberi have also been published, and the ASMBS guideline notes that occurrence may, in fact, not be rare [137,138]. Beriberi can cause irreversible neuromuscular disorders as well as defects in memory. Preoperative deficiency of thiamine has been estimated at 15% to 29% .
Vitamin D is absorbed in the ileum and jejunum, suggesting that deficiency of this nutrient would not be severe following RYGB. However, studies of vitamin D deficiency before and after bariatric surgery suggest that suboptimal levels of vitamin D are quite common preoperatively, making supplementation an issue. In a 2007 series of 95 patients, 54% were vitamin D deficient (<50 nmol/L) and another 34% had suboptimal levels (50–79 nmol/L) . In another study, 80% of preoperative patients had 25-OH vitamin D (the storage form of the vitamin) levels less than 32 ng/mL . The ASMBS estimates that 60% to 70% of obese patients may have low levels of vitamin D preoperatively . Although supplementation has been shown to increase levels following surgery, a pilot study involving 45 post-RYGB patients suggests that, for many patients, current levels of supplementation may not be high enough to normalize levels .
Calcium is primarily absorbed in the duodenum and proximal jejunum. Low calcium intake and low levels of vitamin D can both contribute to deficiency in whole-body calcium, leading to increased bone resorption and potentially osteoporosis . One study, a prospective design with 1 year of follow-up in a small group of patients, found a strong association between declining bone mineral density at the hip and degree of weight loss after RYGB . Intake of both calcium and vitamin D increased after surgery, but most patients continued to have levels of vitamin D less than 30 ng/mL. Deficits in calcium and vitamin D, with associated increases in bone resorption, may also occur after LAGB . The long-term significance of bone density changes is unknown, however. For calcium supplementation, calcium citrate, which does not require high acidity for absorption, may be a better choice than calcium carbonate, particularly in RYGB patients and others with reduced gastric acid.
Recommendations for specific supplements, including dosage, can be found in a guideline published by the ASMBS . Essentially, it is recommended that postsurgery patients take a high-potency multivitamin/mineral supplement, B12, calcium, iron, fat-soluble vitamins (A, D, and K), and an optional B complex . The ASMBS notes that supplementation should be individualized to patient need. Laboratory tests to assess nutrition levels are also recommended.
Anatomical changes are likely not the only cause of nutritional deficiencies after bariatric surgery. The ASMBS guideline notes that purely restrictive surgeries, while once thought not to be associated with nutritional deficiencies, may in fact lead to deficiencies due to poor diet and food intolerance. Research on dietary habits after a restrictive procedure reinforces this concern, as demonstrated in a case study of consecutive patients in one surgical ward who had undergone VBG, a restrictive surgery, between 1986 and 1992 . Sixty-two percent of eligible patients participated, and the average time of follow-up after surgery was 5.4 years. Patients' overall food intake had declined since before surgery, except for fluids, dairy products, and sweet foods. Fruit and vegetable consumption had declined the most, and then meat, fish, and complex carbohydrates. The authors of the study questioned whether the patients' relatively unhealthy diets might eventually counterbalance the benefits of weight loss.
Protein deficiency has been suggested as a concern following RYGB due to malabsorption or following LAGB due to reduced caloric intake and possible food intolerances. In fact, hypoalbuminemia does not appear to be common following bariatric surgery, except perhaps in patients whose diets are very low in protein. It may be more of a problem in patients who undergo more significantly malabsorptive procedures, such as BPD.
The ASMBS recommends somewhat higher than normal levels of protein intake following bariatric surgery, noting that 60–80 g per day is a common amount, although ideal levels have not been determined . Patients with a history of BPD or duodenal switch do need higher levels of protein than the usual recommended amounts; the ASMBS suggests an increase of approximately 30%, for a daily total of about 90 g. These amounts may be modified by individual patient need. Supplementation aimed at reducing protein deficiency following LAGB is being investigated [144,145].
After RYGB, changes in the physical structure of the GI tract can influence the absorption of certain medications. Extended-release formulations that are designed to remain in the intestine for long periods may not be absorbed as well or according to the expected time course . Immediate-release formulations are generally recommended in these patients; however, healthcare providers are not always aware of recommended vitamin regimens, dosages, and appropriate formulations. A retrospective study conducted from 2006 through 2007 in patients with a history of bariatric surgery examined vitamin/nutrient supplements and medication dosage formulations given upon admission. Daily multivitamin, calcium, iron, vitamin B12, and folic acid supplementation were evaluated. Of 133 patient admissions, 88% had a history of a malabsorptive procedure. Approximately 33% of patients were given a multivitamin; 5.1% were given supplemental vitamin B12; 7.7% received supplemental calcium; 11.1% received additional folic acid; and 12% received iron. Inappropriate formulations (e.g., non-immediate-release, enteric-coated) were ordered in 61.5% of patients. Fifty percent of patients were discharged with inappropriate formulations .
Although medication absorption in bariatric surgery patients is not well studied, the reduction in acid due to structural changes in the stomach may alter absorption of medications that require an acidic environment. More pharmacokinetic clinical studies are needed to address the specific effect of RYGB on drug absorption .
Beyond information about nutrition, day-to-day life after bariatric surgery is rarely addressed in the literature. To help illuminate patients' experiences following these procedures, Potoczna and colleagues reported on bowel habits after gastric banding, RYGB, and BPD . Compared to before surgery, patients who had adjustable gastric banding were more likely to report increased constipation at three or more months after surgery. RYGB patients were more likely to report loose stools or diarrhea (46% after surgery compared to 8% before). RYGB patients were also more likely to report malodorous flatus, to be bothered by it, and to feel that their social life was affected. A similar pattern was seen with BPD. For both RYGB and BPD, severity of flatus was inversely correlated with quality of life subscores on the bariatric analysis reporting outcome system scale.
As noted, candidates for bariatric surgery are often required to attempt non-surgical methods of weight loss. Even after surgery, these patients benefit from healthy lifestyle changes to maintain weight reduction and associated benefits.
Studies consistently show that weight loss purely through lifestyle change is a challenge. Some studies have found reductions of only about 3–10 kg over one to two years with either pharmacologic or behavioral treatments .
However, some patients will be able to lose weight and keep it off through increased physical activity and healthier eating. The U.S. Preventive Services Task Force (USPSTF) recommends intensive counseling and behavioral interventions to promote sustained weight loss for obese adults . Counseling may address diet, exercise, or both, and behavioral interventions may be aimed at skill development, motivation, and support. The USPSTF concluded that these strategies could result in a typical weight loss of about 3–5 kg (6.6–11 lbs), lasting one year or more. Some patients will struggle to lose this amount of weight, while others will be able to lose substantially more.
Weight loss of 1 to 2 pounds per week is considered a safe amount for patients making lifestyle changes. To achieve this level of weight loss, patients with a BMI between 27 and 35 should generally reduce their total food intake by 300–500 calories daily. Patients with a BMI greater than 35 should reduce their total intake by 500–1000 calories daily. Patients can check their own caloric needs using a simple calculator at http://www.choosemyplate.gov.
Obese patients may be reluctant to attempt an exercise program or concerned that they will not have the stamina for vigorous exercise. In fact, a simple walking program can serve as the important first step to a healthier lifestyle. If there are no contraindications to exercise, patients can begin with a 10- or 15-minute walk, a few times a week, and build up gradually to recommended levels. Some patients may find it helpful to have exercise advice written out as a "prescription," just as advice to take a certain medication would be.
The specifics of exercise recommendation vary, but most authorities recommend at least 30 minutes of moderate exercise on most days. The 2008 Physical Activity Guidelines for Americans recommend the following minimum levels for adults :
150 minutes (2 hours and 30 minutes) each week of moderate-intensity aerobic activity, such as brisk walking, OR
75 minutes (1 hour and 15 minutes) each week of vigorous-intensity aerobic activity, such as jogging or running, OR
An equivalent mix of moderate- and vigorous-intensity aerobic activity
Also recommended are muscle-strengthening activities, working all major muscle groups, on two or more days a week.
The American Heart Association (AHA) advises 30 minutes of moderate physical activity five days a week or 20 minutes of vigorous activity three days a week, and also suggests that resistance training or other strengthening activities be performed on two or more nonconsecutive days each week .
Both the AHA and the 2008 Physical Activity Guidelines for Americans specify that exercise can be accumulated in shorter bursts [150,151]. Bouts of moderate or vigorous exercise lasting at least 10 minutes can be added together toward the goal.
Some patients will benefit from pharmacotherapy to aid in weight loss. Approval criteria for anti-obesity drugs include a 5% or more mean placebo-subtracted weight loss after one year of therapy or a minimum of 35% of participants achieving more than 5% weight loss. The European Medicines Agency guideline requirements are similar. Both agencies also call for evidence of improvements in metabolic comorbidities . At present, five weight-loss drugs are FDA-approved for long-term use: orlistat, lorcaserin, phentermine/topiramate, bupropion/naltrexone, and liraglutide [152,153,154]. Weight loss achieved through the use of medication tends to be modest, and weight is often regained when the drugs are stopped [155,156,157].
Orlistat inhibits nutrient absorption. Orlistat has been shown to increase weight loss and improve cardiovascular risk factors. Primary side effects are gastrointestinal discomfort and a decrease in absorption of fat-soluble vitamins . Independent reports of liver injuries (including six cases of liver failure between 1999 and 2008) prompted the FDA to approve a label revision for orlistat that includes a warning of possible severe liver injury . However, the risk of severe liver injury is low, and this risk should be weighed against potential benefits . Orlistat is indicated for the treatment of obesity in conjunction with a reduced-calorie diet .
In 2012, the FDA approved both lorcaserin and phentermine/topiramate, the first new weight-loss medication in more than a decade [153,158]. Lorcaserin is a selective 5-HT2C receptor agonist and acts to promote weight loss by giving the patient a feeling of satiety . Trials indicate that lorcaserin is safe and effective treatment, in conjunction with diet modification and exercise, for adults with a BMI ≥30 or adults with a BMI ≥27 with at least one weight-related comorbidity (e.g., hypertension, dyslipidemia, sleep apnea). The recommended dose is 10 mg twice daily . Originally rejected, the manufacturer was required to submit additional safety data, specifically related to the risk for valvular heart disease, prior to approval .
Phentermine/topiramate (extended-release) combines an anorexiant and an anticonvulsant to improve short-term weight-loss outcomes in patients who have already attempted lifestyle changes (i.e., calorie-restricted diet and increased physical activity) . As with lorcaserin, eligible patients will have a BMI ≥30 or a BMI ≥27 with a weight-related comorbidity . The recommended initial dose of phentermine/topiramate is 7.5 mg phentermine/46 mg topiramate extended-release once per day . The dose may be titrated to a maximum of 15 mg/92 mg. The medication is contraindicated in persons with glaucoma and hyperthyroidism and is not recommended for patients with a recent history of stroke or heart disease . It is also teratogenic, with proven fetal defects with first trimester exposure. Therefore, all women of childbearing age should use effective contraception consistently while taking the drug and have documented proof of a negative pregnancy test prior to the initiation of treatment and every month thereafter .
In 2014, combination bupropion/naltrexone was approved as a treatment option for chronic weight management . Studies show that these drugs are effective in improving the percentage of total body weight lost compared to placebo [163,164]. The dosage is gradually titrated up, starting with one tablet (naltrexone 8 mg/bupropion 90 mg) once daily in the morning for one week and increasing one daily tablet each week for four weeks. The maintenance dose is two tablets twice daily . If 5% of initial body weight has not been lost after 12 weeks, the medication should be discontinued.
Any patient taking bupropion should be carefully monitored for suicidal ideation and behaviors . This medication may also increase blood pressure and heart rate and is contraindicated in patients with hypertension. It is also contraindicated in patients with a history of seizures, who are taking another bupropion-containing medication, or who are pregnant.
Also in 2014, the FDA approved liraglutide for use in obese adults (BMI ≥30) and adults who are overweight (BMI ≥27) who have at least one weight-related condition (e.g., hypertension, type 2 diabetes, dyslipidemia) . Liraglutide is a glucagon-like peptide-1 (an incretin hormone) that increases glucose-dependent insulin secretion, decreases inappropriate glucagon secretion, increases B-cell growth/replication, slows gastric emptying, and decreases food intake . The recommended initial dose of liraglutide is 0.6 mg subcutaneously once per day for one week. The dose should be increased by 0.6 mg daily at weekly intervals until a target dose of 3 mg once daily is achieved . Liraglutide is contraindicated in individuals with hypersensitivity to the drug or to any component of the formulation. The drug is also contraindicated in pregnant patients, patients with a history/family history of medullary thyroid carcinoma, and patients with multiple endocrine neoplasia syndrome. Liraglutide carries a boxed warning of thyroid C-cell tumor risk. Increased heart rate, headache, and gastrointestinal complaints (i.e., nausea/vomiting, diarrhea, constipation) are the most common side effects .
Until October 2010, another drug, sibutramine, was approved by the FDA for use in the long-term management of weight. Randomized controlled trials supported the efficacy of sibutramine for short-term weight loss, with associated improvements in glycemic control, triglyceride levels, and HDL . However, postmarketing data indicated that patients with existing cardiovascular disease on long-term sibutramine therapy had an increased risk of nonfatal myocardial infarction and stroke . As a result, the manufacturer (Abbott Laboratories) responded to an FDA request by voluntarily removing the agent from the U.S. market .
Medication, if it is used, should be part of an overall plan for lifestyle change. There is some research to suggest that the combination of medication and lifestyle counseling may be more effective than medication alone. Wadden and colleagues conducted a randomized trial with 224 patients assigned at random to one of four tracks: sibutramine, 30 group sessions of lifestyle counseling, a combination of counseling and sibutramine, or sibutramine with brief counseling by primary care provider. After 1 year, the combined therapy patients lost 12.1 kg. The patients using sibutramine alone lost 5.0 kg, lifestyle counseling alone 6.7 kg, and sibutramine plus brief counseling 7.5 kg. Sibutramine combined with brief therapy and lifestyle counseling also produced more weight loss than sibutramine alone .
Weight loss has been demonstrated to be a highly effective means of reducing or eliminating obesity-related comorbidities, including diabetes, hypertension, and hyperlipidemia, and of reducing overall cardiometabolic risk. Bariatric surgery provides substantial weight loss, with surgical mortality rates of less than 1%, and current guidelines recommend considering this option for severely obese patients and those with BMI of 35 or greater if comorbidities are present. All of the options for weight loss should be thoroughly discussed with patients, including the benefits, risks, and challenges.
|American College of Surgeons|
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