Surgical treatment of adult obesity
Despite a growing global obesity epidemic over the past two decades, lifestyle interventions and pharmacological treatments for obesity have faltered, especially for severely obese patients. In contrast, bariatric surgery is gaining momentum, evidence is growing, and important short- and long-term efficacy and safety data are emerging from studies of surgical treatment of obesity and related metabolic abnormalities. Because bariatric surgery carries both risks and benefits, the purpose of this article is to guide patients and their clinicians by detailing bariatric surgery and the shared decision-making process.
Prevalence profile of obesity
Based on estimates from a nationally representative sample, 35.5% of adults in the United States were obese (BMI ≥ 30), 15.5% were BMI ≥ 35, and 6.3% were severely obese (BMI ≥ 40) in 2009-2010.
Other countries still lack data on the prevalence of severe obesity, but data from the British Health Survey show that 1.7% of men and 3.1% of women in the UK had a BMI ≥ 40 in 2012; 1.3% of men in Sweden had a BMI ≥ 35 in 2005; and 8.1% of adults in Australia had a BMI ≥ 35 in 2006.
In 2011, there were an estimated 340,768 bariatric procedures performed worldwide, with the most common procedures being Roux-en-Y gastric bypass (46.6%), vertical sleeve gastrectomy (27.8%), adjustable gastric banding (17.8%), and biliopancreaticoduodenal diversion (2.2%). The countries with the highest number of procedures were the United States and Canada (101,645 cases in total), followed by Brazil (65,000 cases), France (27,648 cases), Mexico (19,000 cases), Australia and New Zealand (12,000 cases in total), and the United Kingdom (12,000 cases), while no other country reached 10,000 cases or more in 2011.
Obesity-related complications
Severe obesity (defined as BMI ≥ 35 with disease or BMI ≥ 40 without concomitant disease) is a very common chronic disease, which can not only cause a large number of disability, premature death, affecting the quality of life, but also a large increase in medical expenditure. In addition, severely obese adults also suffer disproportionately from various chronic diseases, such as type 2 diabetes (28%), major depression (7%), coronary heart disease (14-19%) and osteoarthritis (10-17%).
Treatment of obesity
Treatments for severe obesity include lifestyle interventions, medications, and bariatric surgery. For decades, evidence from studies on weight loss has shown that lifestyle interventions and pharmacotherapy are often ineffective in improving long-term health and quality of life in patients with severe obesity. However, a growing body of evidence has found that bariatric surgery can sustain weight loss, improve concomitant disease, and prolong survival.
The first bariatric surgery was performed more than 50 years ago, but over the past 20 years, the number of bariatric surgeries in the United States has increased 20-fold per year due to a marked increase in severe obesity and improvements in the effectiveness and safety of the procedure. Recent improvements in the safety of bariatric surgery have been driven by an increase in volume, a shift to laparoscopic techniques, and an increase in low-risk adjustable gastric banding procedures. Recently, U.S. guidelines have recommended that bariatric surgery be considered for the following groups: BMI ≥ 40 with poor non-surgical outcomes; BMI ≥ 35 with severe obesity-related disease.
Classification of bariatric surgery and its weight loss mechanisms
Bariatric surgery has changed significantly over the past 50 years. Surgery is now often described in anatomical terms based on its presumed mechanistic effects, using phrases such as “gastric restriction” or “small bowel bypass” to make it easy to understand, but recent basic science research is likely to change this physiologically based characterization. description. In addition, since the 1990s, the standard surgical approach (almost exclusively) has shifted from open incision to minimally invasive or laparoscopic.
The first widely used bariatric surgery was jejuno-ileal bypass, which involved the use of a small bowel bypass connecting the proximal jejunum to the terminal ileum, resulting in extreme weight loss by producing severe absorption disturbances. However, the procedure was eventually abandoned years later due to severe protein-energy deficiencies in many patients.
Different types of bariatric surgery
1. The main types of bariatric surgery
The main bariatric procedures that followed were horizontal gastroplasty and vertical with gastric septum, the latter of which had the potential to become a purely restrictive procedure due to the development of surgical suturing devices. In horizontal gastroplasty, the upper part of the stomach is sutured horizontally, with a spacer containing many small holes (allowing food to pass through) to form a pouch (Figure A). In the vertical plus banded gastric septum procedure, the vertical suture is closed parallel to the lesser curvature of the stomach and the outlet or small hole is reinforced with a mesh collar to prevent enlargement (Figure B). Both of these surgical approaches have now been abandoned due to the introduction of newer, more effective laparoscopic techniques and the frequent separation of the sutured band in the stomach or the tendency of the foramen ovale to enlarge leading to weight rebound or severe gastroesophageal reflux.
The gastric bypass procedure was first used in 1969 by Mason and Ito and then modified to drain the proximal gastric pouch to avoid bile reflux as the Roux-en-Y gastric bypass procedure (Figure C). Over time, Roux-en-Y gastric bypass has evolved into the more recent laparoscopic form, which consists of a 15-20 ml size proximal gastric pouch, a smaller gastric-intestinal access hole (with or without sleeve restriction), and a stapled line with complete transverse closure (to prevent separation or closure failure) (Figure D).
Another major surgical modality is the adjustable gastric banding procedure, which has been modified for laparoscopic placement to form a pouch with adjustable outlet size in the upper part of the stomach (Figure E). The adjustable gastric band uses a silicone band containing an inflated balloon, which is fastened to form a closed loop that is secured to the upper part of the stomach, with the other part placed subcutaneously to adjust the outlet size.
Two other more extreme small bowel bypasses (with a modest reduction in gastric volume) are biliopancreatic diversion and biliopancreaticoduodenal diversion, which are usually used in “super” obese patients (usually BMI ≥ 50). (Figure F) shows a biliopancreatic diversion combined with a subtotal (2/3) distal gastrectomy and a long Roux-en-Y gastrointestinal anastomosis and a shorter small bowel for nutrient absorption. (Figure G) shows a biliopancreaticoduodenal diversion combined with more than 70% gastric curve resection and a long small bowel bypass, while the duodenal stump is “de-functionalized” or “converted” to a gastro-ileal anastomosis.
More recently, the main procedure is the vertical sleeve gastrectomy, which is becoming increasingly popular and consists of a vertical resection of 70% of the stomach to form a long, narrow tubular gastric channel without a small bowel bypass (Figure H).
2. Mechanisms of weight loss
Although bariatric surgery has been anatomically conceptualized as basically “restriction” and “small bowel bypass,” there are still many animal and human studies that are investigating the underlying mechanisms behind the procedure, which should be more physiologically oriented (altered gastrointestinal signaling) than not just limiting nutrient absorption, but in essence are also likely to be the result of a combination of endocrine and neurological alterations, among others.
Some of the potential mechanisms include alterations in gastric hunger hormone, leptin, glucagon-like peptide-1, cholecystokinin, peptide YY, intestinal flora, and bile acids. In the future, bariatric surgery will not only be based on anatomical surgical similarities, but also to clarify how it affects key physiological indicators so that it is possible to further understand the rationale for the mechanisms involved.
Bariatric surgery vs. non-surgical treatment
The following table summarizes the results of bariatric surgery versus non-surgical treatments for the treatment of obesity from randomized trials and major long-term observational studies, including the impact of weight change, form of remission and prevalence of type 2 diabetes, and long-term survival.
Studies
Study Details
Weight Change
T2DM remission
T2DM prevalence
Mortality and survival impact
Meta-analysis
Eleven RCTs (n=796) comparing RYGB, AGB, BPD, VSG and non-surgical treatments were included
The mean difference in weight change between 1-2 years of bariatric surgery treatment compared with non-surgical treatment was -26 kg, 95% CI -31 to -21; P<0.001
The relative risk (RR) for complete case analysis of bariatric surgery compared with non-surgical treatment was 22.1, 95% CI
3.2-154.3; P=0.002; conservative analysis RR=5.3, 95% CI 1.8-15.8; P=0.003
Not reported
No cardiovascular event deaths reported after bariatric surgery or in control population
Swedish Obese Subjects Study
Prospective observational study with matched controls (n=2010, 68% VBG, 19% banding surgery, 13% RYGB), 2037 cases in matched control group
Bariatric surgery group: mean weight change after 2, 10, 15, and 20 years of treatment was -23%, -17%, -16%, and -18%, respectively; matched group: mean weight change after 2, 10, 15, and 20 years of treatment was 0%, 1%, -1%, and -1%, respectively.
Bariatric surgery treatment: 72% remission at 2 years (OR=8.4, 5.7-12.5; P<0.001); 36% sustained remission at 10 years ((3.5, 1.6-7.3; P<0.001), and 96%, 84% and 78% reduction in risk of diabetes at 2, 10 and 15 years after bariatric surgery, respectively, for patients without T2DM at baseline, compared with usual treatment There was a 29% reduction in the risk of all-cause mortality after 16 years of bariatric surgery compared with usual treatment (HR=0.71, 0.54-0.92; P=0.01).
Utah Mortality Study
Retrospective observation and matched controls (7925 RYGB and 7925 matched controls)
Not reported
Not reported
Not reported
All-cause mortality, cardiovascular mortality, and type 2 diabetes mortality were reduced by 40%, 49%, and 92%, respectively, at a mean of 7.1 years after surgery
Utah Obesity Study
Prospective observational and matched control study enrolling 418 RYGB, 417 non-operated (control group 1), and 321 severely obese matched controls (control group 2)
Weight change after 6 years was -27.7%, +0.2% and 0% for patients in the surgery group, control group 1, and control group 2, respectively
The 6-year remission rates were 62%, 8% and 6% for patients in the surgery group, control group 1 and control group 2, respectively
Diabetes onset at 6 years was 2, 17 and 15 % in the surgery group, control group 1 and control group 2, respectively
6-year mortality was 12 (2.8%), 14 (3.3%), and 3 (0.93%) for patients in the surgery group, control group 1, and control group 2, respectively
AGB = adjustable gastric banding procedure; BPD-DS = biliopancreaticoduodenal diversion; RYGB = Roux-en-Y gastric bypass; VSG = vertical sleeve gastrectomy
1. Randomized controlled trials
A recent systematic review and Meta-analysis summarized all randomized controlled trials comparing bariatric surgery and non-surgical treatments for the treatment of obesity, including 11 trials with a total of 796 patients (BMI 30-52), which focused on patients with type 2 diabetes with 1-2 years of follow-up, and also provided information on bariatric surgery such as Roux-en-Y gastric bypass, adjustable gastric banding, biliopancreatic diversion, and vertical sleeve gastrectomy. Gastrectomy and other bariatric procedures provide good evidence. These procedures result in greater weight loss and remission of type 2 diabetes in the short term (1-2 years) compared to different non-surgical treatments. Recently, two other small randomized controlled trials found similar short-term weight loss and type 2 diabetes remission to the above analysis.
In addition, bariatric surgery significantly reduced serum triglyceride and HDL levels, but had little effect on blood pressure and other lipoproteins (although some studies reduced them in the presence of medication). Evidence of mortality, cardiovascular disease and adverse events over two years was missing from the inclusion of fever randomized controlled trials in this systematic review.
More recently, another systematic review included three randomized controlled trials focusing on weight loss and glycemic control in adults with class I obesity (BMI 30-34.9) in combination with type 2 diabetes, and the results of the analysis were similar to those of patients with class II obesity (BMI 35-39.9) and severe obesity, but the review also lacked data from long-term studies.
2, Swedish obese subjects study
Due to the lack of long-term comparisons of bariatric surgery and non-surgical treatment in randomized controlled trials, we should turn to long-term observational cohort studies to clarify the long-term outcomes of bariatric surgery. Most of the data on the long-term outcomes of bariatric surgery are from the Swedish Obese Subjects (SOS) study. This prospective study was initiated in 1987 and included 2010 bariatric surgery patients and 2037 matched controls receiving conventional treatment.
The most common surgical procedure in the SOS study was vertical sleeve gastrectomy (68%), followed by gastric banding (19%) and Roux-en-Y gastric bypass (13%). The follow-up rate for the same endpoint (including mortality) was 99%, but the lower follow-up rate for physical examination and laboratory tests was associated with the use of sensitivity analysis.
The SOS investigators published a number of study outcomes related to the study over 10 years, such as weight loss, mortality, reduction in the incidence of type 2 diabetes, cardiovascular events, cancer, psychosocial impact, and health insurance use and spending.
In the SOS study, weight loss was significantly greater in surgical patients than in control patients (mean weight change in the bariatric surgery group was -23%, -17%, -16%, and -18% after 2, 10, 15, and 20 years of treatment, respectively; in the matched group were 0%, 1%, -1%, and -1%, respectively), and after 15 years, the mean weight loss by procedure was 27% (Roux-en-Y gastric bypass), 18% (vertical plus band gastric septal surgery), and 13% (gastric banding), respectively.
Patients also had dramatic improvement in obesity-related coexisting conditions, with 72% 2-year remission of type 2 diabetes after bariatric surgery (OR=8.4, 5.7-12.5; P<0.001); and 36% 10-year sustained remission ((3.5, 1.6-7.3; P<0.001). < span="">
Over time, there was a lower prevalence of myocardial infarction after bariatric surgery (HR=0.56,0.34-0.93; P=0.025) and fewer other complications of type 2 diabetes, despite a number of recurrences of type 2 diabetes after bariatric surgery. The SOS study also recently found that the risk of progression to type 2 diabetes was also significantly lower after bariatric surgery.
3, Utah obesity study
Another important long-term observational study is the 1984-2002 Utah Obesity Study, which included 7,925 patients who received Roux-en-Y gastric bypass surgery and recruited 7,925 weight-, age- and sex-matched control patients. The study found that all-cause mortality, cardiovascular death, and type 2 diabetes death were each reduced by 40% in the surgery group after a mean of 7.1 years (HR=0.60, 0.45-0.67;
P<0.001)), 49% (0.51, 0.36 -0.73; P<0.001), and 92% (0.08, 0.01 to 0.47;
P=0.005).
Two large retrospective studies likewise support the SOS study and the Utah study that bariatric surgery reduces mortality compared with usual treatment. However, a retrospective study of U.S. veterans found that bariatric surgery did not improve survival after a mean of 6.7 years of follow-up compared to usual treatment.
And in another ongoing independent Utah obesity study, investigators proposed to look at more than 400 patients who underwent Roux-en-Y gastric bypass surgery and two other non-randomized matched control groups containing 400 severely obese individuals each. One control group 1 was patients who were expected but not yet surgically treated, and control group 2 was obese patients in the population. The study found that after 6 years, patients in the surgery group, control group 1, and control group 2 lost -27.7%, +0.2%, and 0% of their body weight at 6 years; diabetes remission rates were 62%, 8%, and 6%, respectively; and diabetes onset was 2%, 17%, and 15%, respectively.
4. LABS-2 study
When it comes to bariatric surgery, the Longitudinal Assessment of Bariatric Surgery (LABS-2) study has to be mentioned because it is the largest ongoing multicenter observational cohort study to date, although it did not include a non-surgical control group. 2,458 participants were recruited in LABS-2 from 2005-2009, including 1,738 Roux-en-Y gastric bypass procedures; 610 adjustable gastric banding procedures; and 110 adjustable gastric banding procedures. adjustable gastric banding; and 110 other surgical procedures, which have been followed for 3 years to date.
The median weight change for Roux-en-Y gastric bypass and adjustable gastric banding was 31.5% and 15.9%, respectively, and there was still a significant difference between the different surgical procedures; the remission rate of type 2 diabetes was 67% and 28%, respectively; and the incidence of type 2 diabetes was 0.9% and 3.2%, respectively.
5. Impact on long-term quality of life
Although few studies have evaluated the impact of bariatric surgery on quality of life, three of the six studies, which lasted 10 years, showed that bariatric surgery had significant improvements in general and obesity-specific related quality of life compared to non-surgical procedures, and that improvements in physical function were superior to those in mental health, although further research is needed in this area, particularly in patients with Class I obesity.
Comparison of the effectiveness of different bariatric procedures
Over the past decade, many systematic reviews of bariatric surgery have attempted to summarize and quantify the differences in the safety and effectiveness of different surgical approaches. However, one of the major challenges in this review is that none of the randomized trials included the most common surgical modalities (Roux-en-Y gastric bypass, vertical sleeve gastrectomy, adjustable gastric banding, biliopancreaticoduodenal diversion), so inferences can only be drawn from a pooled analysis of many different randomized and nonrandomized bariatric surgery studies. Beyond this, there are no trials comparing the differences in long-term survival, cardiovascular events, and quality of life between bariatric procedures.
One of the most comprehensive systematic reviews included analysis of 136 studies with a total of 22,094 patients undergoing bariatric surgery, but only 5 of these were randomized studies and did not include data from vertical sleeve gastrectomy, leaving 28 nonrandomized controlled trials and 101 noncontrolled case series. The review showed that weight loss tended to vary significantly by surgical modality, with weighted mean percentages (%EWL) of excess weight loss for adjustable gastric banding, Roux-en-Y gastric bypass, vertical sleeve gastrectomy, and biliopancreaticoduodenal diversion being 50% (32%-70%), 68% (33%-77%), 69% (48%-93%), and 72 percent (62%-75%). Also, the remission rate of type 2 diabetes varied significantly by surgery, with 48% (29%-67%), 84% (77%-90%), 72% (55%-88%), and 99% (97%-100%), respectively. In addition, remission rates were similar for different diseases such as hypertension, dyslipidemia, and obstructive sleep apnea, while patients undergoing biliopancreaticoduodenal diversion had the highest remission rates, followed by Roux-en-Y
gastric bypass surgery and vertical plus band gastric septal surgery, and finally adjustable gastric banding surgery.
1. Roux-en-Y gastric bypass vs.
Adjustable gastric banding
The difference in effectiveness of Roux-en-Y gastric bypass and adjustable gastric banding, the two most common surgical procedures, in terms of weight loss and concomitant disease improvement is still much debated. Consistent with the systematic reviews mentioned above, many other systematic reviews have also found Roux-en-Y gastric bypass to be superior to adjustable gastric banding for weight loss, but only two small head-to-head randomized controlled studies (follow-up to year 4-5) have been performed in this regard.
There is a lack of sufficient data from randomized controlled studies comparing Roux-en-Y gastric bypass with adjustable gastric banding in terms of concomitant disease improvement. However, a systematic review of nonrandomized studies found higher rates of remission of type 2 diabetes, hypertension, dyslipidemia, and sleep apnea after Roux-en-Y gastric bypass. In contrast, a systematic review of 19 long-term observational studies (≥10 years, non-RCTs) showed a mean %EWL of 54.2% and 54% for Roux-en-Y gastric bypass and adjustable gastric banding procedures, respectively.
These different data remind us that adjustable gastric banding is not inferior to Roux-en-Y gastric bypass in terms of weight loss in some experienced surgical centers with high volumes and rigorous standardization of long-term postoperative treatment and follow-up, but data from such centers are not common in the surgical literature and the optimal need for adjustable gastric banding requires further study.
2. Vertical sleeve gastrectomy vs.
Other Surgical Modalities
Two recent systematic reviews have compared vertical sleeve gastrectomy with other surgical approaches. One included 15 randomized controlled trials of 1191 patients with follow-up ranging from 6 months to 3 years, and found that the ranges for vertical sleeve gastrectomy, Roux-en-Y gastric bypass, and adjustable gastric banding %EWL were 49%-81%, 62%-94%, and 29%-48%, respectively; vertical sleeve gastrectomy and Roux-en-Y gastric bypass type 2 diabetes remission rates ranged from 27%-75% and 42%-93%, respectively.
The second review compared only the differences between vertical sleeve gastrectomy and Roux-en-Y gastric bypass, for which a total of six randomized controlled trials and two nonrandomized controlled studies were included, with follow-up ranging from 3 months to 2 years. The analysis found that Roux-en-Y gastric bypass significantly reduced BMI compared to vertical sleeve gastrectomy (mean difference in BMI 1.8; 0.5-3.2); and also significantly improved total cholesterol, HDL cholesterol and insulin resistance.
Clearly, further data on the long-term effectiveness of vertical sleeve gastrectomy are needed, but it seems safe to assume that the effect of vertical sleeve gastrectomy on weight loss and improvement in concomitant disease is somewhere between Roux-en-Y gastric bypass and adjustable gastric banding.
Complications of bariatric surgery
Bariatric surgery also carries risks. Although perioperative mortality in the general patient population is low (<0.3%) and decreasing, it varies widely among the population, with some patients having a perioperative mortality rate of 2.0% or higher. The incidence of complications associated with bariatric surgery 30-180 days after the procedure ranges from 4% to 25%, depending on the definition of the complication, the surgical approach, the duration of follow-up and the patient.
1. Findings of the main study
In the 11 (796 patients) randomized controlled studies comparing surgical versus non-surgical differences, the incidence of adverse events was higher in the surgical group, but follow-up was limited to 2 years, with no cardiovascular events or deaths between either group, but the most common postoperative adverse events were iron deficiency anemia (15% for small bowel bypass) and reoperation (8%). The number of cases in these randomized controlled studies remains insufficient in terms of comparing the safety of different procedures, and most of the comparative data on complications are mainly from observational studies.
The LBSA-1 study prospectively evaluated complications at 30 days after surgery in 4776 severely obese patients who underwent their first bariatric surgery in 2005-2007, including adjustable gastric banding (25%), laparoscopic Roux-en-Y gastric bypass (62%), open Roux-en-Y gastric bypass (9%), and other types of surgery (3 %).
The 30-day mortality rate for all procedures was 0.3%, and the incidence of the primary adverse outcome (primary composite endpoint including death, venous thromboembolism, reintervention [percutaneous, endoscopic, or surgical], or hospital stay longer than 30 days) was 4.1%; the main predictors of increased risk of complications were previous venous thromboembolism, obstructive sleep apnea, functional impairment status (walking distance <61 m) Very high BMI (≥60) and the use of open Roux-en-Y gastric bypass.
In other studies such as SOS, the complication rate was higher, with at least 14.5% of patients experiencing at least one nonfatal complication within 90 days postoperatively, including (in order of frequency) pulmonary complications, vomiting, wound infection, bleeding, and anastomotic fistula. However, the SOS study was dominated by open surgery and vertical sleeve gastrectomy, and such procedures are rare today. Nevertheless, the 90-day mortality rate in the SOS study was 0.25%.
A Meta-analysis of 361 studies (97.7% non-randomized, observational) with a total of 85,048 patients found significantly different 30-day mortality rates for different laparoscopic procedures. The mortality rates for adjustable gastric banding, vertical sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreaticoduodenal diversion were 0.06 (0.01%-0.11%, 0.21% (0.00%-0.48%), 0.16% (0.09%-0.23), and 1.11% (0.00%-2.70%), respectively; those for open surgery were mortality rate was significantly higher than that of laparoscopic surgery.
In addition, a study of 9,382 patients found that a prognostic risk score consisting of five clinical indicators (BMI ≥50, male, hypertension, known risk factors for pulmonary embolism, and age ≥45 years) was effective in predicting 90-day mortality after Roux-en-Y gastric bypass surgery in the clinic. Patients with 4-5 clinical indicators had a higher risk of death (4.3%) compared to those with no or only one clinical indicator (0.26%).
A systematic review of 15 randomized controlled trials of vertical sleeve gastrectomy showed that none of the 795 patients died, but the mean complication rate amounted to 9.2% (0%-18%). According to the American Surgeons Bariatric Surgery Network database, the 30-day mortality rate for vertical sleeve gastrectomy was 0.11%, between adjustable gastric banding (0.05%) and Roux-en-Y gastric bypass (0.04%). The 30-day complication rates for vertical sleeve gastrectomy, adjustable gastric banding, and Roux-en-Y gastric bypass were 5.6%, 1.4%, and 5.9%, respectively.
2. Re-operation
A worrying trend is the increased rate of reoperation due to complications or/and inadequate weight loss, especially for adjustable gastric banding procedures. In a prospective cohort study of 3227 patients undergoing this type of surgery, 1116 patients (35%) underwent readjustment surgery, primarily due to proximal enlargement (26%), outlet or tubing problems (21%) and erosion (3.4%), with no acute band slippage reported. Acute band slippage was not observed, but the band was eventually removed in 5.6% of patients.
Other long-term cohorts have shown that the rate of adjustable gastric band removal may be as high as 50%. At the 3-year follow-up of the LABS-2 cohort study, the rate of corrected surgery or reoperation was higher for adjustable gastric banding than for Roux-en-Y gastric bypass surgery. However, a systematic review of long-term studies found that corrective surgery rates for adjustable gastric banding (26%, 8%-60%) were comparable to those for Roux-en-Y gastric bypass (22%, 8-38%).
Many of the corrective surgeries are likely due to weight regain or inadequate weight loss, but the specific reasons for corrective surgery are often not mentioned. The higher reoperation rate for adjustable gastric banding compared to other relatively permanent procedures may simply reflect the modifiable nature of the procedure. In conclusion, more long-term data are still necessary for all surgical approaches to bariatric surgery to classify and understand the causes, nature, and severity of these complications.
3. Psychosocial risks
A growing number of observational studies have found an increased long-term risk of substance abuse, suicide, and malnutrition following partial bariatric surgery. Pharmacokinetic studies have shown accelerated alcohol absorption and significantly increased blood alcohol concentrations after Roux-en-Y gastric bypass surgery and vertical sleeve gastrectomy with the same amount of alcohol, thus potentially increasing the frequency of physiological binge drinking and subsequent alcohol abuse.
The SOS study found that Roux-en-Y gastric bypass surgery increased alcohol consumption and alcohol abuse events over a 20-year period (HR=4.9), but more than 90% of patients still drank below the World Health Organization cutoff value for low-risk drinking. Similarly, in the LABS-2 study, alcohol abuse after Roux-en-Y gastric bypass surgery was more likely to occur in the second postoperative year (9.6%) compared with the baseline period (7.6%).
It is possible that the risk of suicide is increased after bariatric surgery, although the associated cause is unknown. In the Utah Mortality Study, Roux-en-Y gastric bypass surgery was associated with a 58% increase in all non-disease-caused deaths compared to matched control patients, with a significant increase in suicide, accidental death, and poisoning deaths (a small percentage), a finding similar to that found in the second Utah Obesity Study.
Another observational study also found that suicide rates were significantly higher in patients after bariatric surgery than in age- and sex-matched control patients in the United States. Considering the lack of perioperative psychosocial risk assessment and long-term follow-up data after bariatric surgery, more rigorous research is still needed in the future to further guide guideline development and standardize treatment criteria.
4. Malnutrition
There is evidence that vitamin and mineral deficiencies such as vitamin D, calcium, iron, zinc and copper are common after bariatric surgery. The guidelines recommend screening patients for iron, vitamin B12, folic acid, and vitamin D prior to surgery; patients should routinely be given daily nutritional supplements after surgery, including two adult multivitamin and mineral supplements (each containing iron, folic acid, and vitamin B1), 1200-1500 mg of calcium, at least 3000 IU of vitamin D, and vitamin B12 as needed.
In addition to this, patients should be screened annually for specific vitamin and mineral deficiencies, as detailed in the table below. There is still insufficient evidence on the optimal dietary and nutritional treatment after bariatric surgery, including how to treat certain postoperative complications such as chronic nausea and vomiting, hypoglycemia, anastomotic ulcers and stenosis, and bariatric failure.
Recommended
AGB
VSG
RYGB
BPD-DS
Bone density monitoring at year 2 (dual energy X-ray absorptiometry)
Yes
Yes
Yes
Yes
24-hour urinary calcium excretion at month 12 and month 6
Yes
Yes
Yes
Yes
Monitor vitamin B12 annually and every 3-6 months after supplementation
Yes
Yes
Yes
Yes
Monitor folic acid, iron metabolism indicators, vitamin D and parathyroid hormone
No
No
Yes
Yes
Pre-operative and post-operative monitoring of vitamin A every 6-12 months
No
No
Elective
Yes
Assess copper, zinc and selenium
No
No
Yes
Yes
Assessment of vitamin B1
Yes
Yes
yes
Yes
Indications for bariatric surgery in relevant guidelines and their limitations
In 1991, the first bariatric surgery guidelines were developed at the National Institutes of Health (NIH) consensus conference, but the evidence was based only on the limited literature available at that time, with the initial selection criteria for patients with BMI ≥40 or BMI 35.0-39.9 with one or more obesity-related conditions. NIH enrollment criteria for open or laparoscopic bariatric surgery, and many individual insurance and state Medicaid programs followed suit.
Recently, the Centers for Medicare and Medicaid Services (CMS) covered Medicare beneficiaries for open and laparoscopic Roux-en-Y gastric bypass surgery, laparoscopic adjustable gastric banding surgery, and open and laparoscopic biliopancreaticoduodenal diversions.
In addition, in 2012, CMS determined that local Medicare Administrative Contractors could separately determine Medicare coverage for laparoscopic vertical sleeve gastrectomy. 2009, CMS added a reimbursement requirement that the procedure be performed in a “center of excellence,” but because it did not improve outcomes for Medicare beneficiaries, CMS In 2013, CMS eliminated this requirement. Although the NIH guidelines developed in 1999 remain the most widely accepted criteria for bariatric surgery, many experts believe the guidelines need to be updated because they do not take into account age, race, or ethnicity, particularly with regard to low BMI ranges and the severity of coexisting conditions.
In 2007, 50 members of the International Multidisciplinary Diabetes Surgery Summit Consensus Conference concluded that there was insufficient evidence to screen patients for surgical treatment of diabetes based on strict BMI criteria. For patients with moderate obesity (BMI 30-35) who are not well controlled by traditional pharmacologic or lifestyle interventions and who have comorbid type 2 diabetes, the consensus was that there was a need to update the guidelines.
30-35), the consensus concluded that Roux-en-Y gastric bypass surgery could be considered with caution. The consensus did not address the use of adjustable gastric banding surgery or other bariatric procedures for people with low BMI.
These recommendations were supported by 21 professional and scientific organizations. However, in 2009, CMS deemed bariatric surgery “unreasonable and unnecessary” for patients with a BMI below 35 and comorbid type 2 diabetes and therefore eliminated Medicare coverage. Despite CMS’ elimination of coverage, the strength of the FDA’s evidence for this choice was questioned in 2011 when the FDA began to support laparoscopic adjustable gastric banding for adults with a BMI of 30-35 and at least one comorbid obesity-related condition. Ultimately, the 2103 bariatric surgery guidelines were updated for perioperative nutritional, metabolic, and nonsurgical support.
Costs
There continues to be debate about the adequacy of bariatric surgery to reduce expenditures and save money. In two early observational studies, bariatric surgery appeared to result in short-term cost savings, but two more recent observational studies (including an analysis of 29,820 enrollees in the Blue Cross Blue Shield Association) did not find a reduction in costs.
In general, evidence suggests that discharge costs, including medications, decrease after bariatric surgery, but long-term hospital costs remain the same or even increase for bariatric surgery patients compared to matched non-surgical patients, so the net cost benefit of bariatric surgery remains to be seen. Findings from observational cohort studies are consistent with earlier cost-effectiveness model assessments. These assessments suggest that bariatric surgery may be more cost-effective than conventional pharmacotherapy or intensive lifestyle interventions for severely obese patients, but does not result in cost savings.
Shared decision making in the treatment of obesity
Given the risks, benefits, and uncertainty of long-term outcomes of bariatric surgery, the choice of this procedure should be based on a shared decision-making process. An integral part of the decision-making process includes clear communication of the clinician’s professional judgment and clarification of the patient’s own value criteria and preferences as well as patient assistance decisions, providing the patient with objective information about all appropriate treatment options and encouraging meaningful patient participation in decision-making. A randomized controlled study found that the use of videos to guide patients in their choice of bariatric surgery significantly improved patient knowledge, decisional conflicts, and expectations of outcomes compared with the NIH-provided bariatric surgery education pamphlet.
The 1991 NIH Bariatric Surgery Consensus Conference supported the following shared decision-making approach.
1. all patients should be given the opportunity to discuss with their physicians any previously overlooked surgical options and the advantages and disadvantages of each procedure
2. Physicians must fully discuss with patients the following issues.
(1) the possible outcomes of the procedure
(2) The likely duration of remission for each procedure that will resolve the patient’s problem
(3) The need for postoperative treatment compliance
(4) Possible short- and long-term complications of surgery
(3) The need for lifelong medical surveillance after surgery is clarified
(4) After considering all of the above, the patient should be adequately guided through the independent choice of treatment.
Looking Ahead
Many important studies are underway in the field of bariatric surgery, including prospective and retrospective studies, and randomized controlled studies comparing contemporary surgical versus non-surgical treatments for severely obese patients. The LABS-2 study mentioned above will answer questions about the efficacy and safety of surgical treatment and the duration of weight loss and health improvement, and 3 years of data from this study will be published soon with a planned 7-year follow-up.
Seven NIH-supported randomized controlled studies are also underway or completed, and at least 13 international randomized controlled studies are underway. In the coming years, these randomized controlled studies will provide more definitive data on the effectiveness of bariatric surgery in the short term than conventional treatment or intensive pharmacotherapy or lifestyle interventions, especially for patients with comorbid type 2 diabetes and a BMI of 30.0-39.9. In addition to this, some of the randomized controlled trials are recently being planned for 5 years or more of follow-up, so more long-term outcome data will emerge.
In ongoing observational studies such as the Utah Obesity Study, the Michigan Bariatric Surgery Collaborative Study, and research cohorts from the Network of Health Maintenance Organizations and the U.S. Department of Veterans Affairs, important data comparing the effectiveness, safety, and cost of surgical and non-surgical treatments are likely to emerge over the next 5 years, and will also provide important data on weight loss and health improvement (also including microvascular disease and cancer).
Conclusion
High-quality evidence from randomized controlled studies clearly demonstrates that bariatric surgery is more effective than pharmacotherapy or lifestyle interventions for weight loss and initial remission of type 2 diabetes, even in less obese patients (BMI 30-39.9). Although evidence from randomized controlled studies is not older than 2 years, a small number of rigorous observational studies have shown encouraging results, with improved long-term survival, reduced annual risk of cardiovascular disease and diabetes, and longer-lasting improvements in obesity-related concomitant disease in patients who underwent bariatric surgery compared to matched control non-surgical participants.
However, bariatric surgery carries the same risks. Perioperative mortality rates (<0.3%) are low and decreasing in the general patient population, but vary widely among patients, with some patients experiencing perioperative mortality rates of 2.0% or higher. The incidence of postoperative complications varies from 4% to 25%, depending on the duration of follow-up, definition of complications, surgical approach, and patient.
An increasing number of observational studies have found an increased long-term risk of substance abuse, suicide, and malnutrition after partial surgery. More research is needed to assess differences in long-term outcomes across patients with different procedures and to clarify which group of patients is likely to benefit from surgical treatment. Because the long-term risks or benefits of bariatric surgery have been unclear, decisions about surgery should be based on a high-quality decision sharing process.