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Comparative Effectiveness of Bariatric Surgery and

Nonsurgical Therapy in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9

kg/m2

Prepared for:

Agency for Healthcare Research and Quality (AHRQ)

www.ahrq.gov

Introduction to bariatric surgery and its role in the management of obesity and associated metabolic conditions

Systematic review methods The clinical questions addressed by the comparative

effectiveness review Results of studies and evidence-based conclusions

about the comparative effectiveness and safety of various bariatric surgical procedures in adults with metabolic conditions and a body mass index of 30.0 to 34.9 kg/m2

Gaps in knowledge and future research needs What to discuss with patients and their caregivers

Outline of Material

Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82.Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.

Bariatric surgery or weight-loss surgery refers to surgery usually performed in patients with a body mass index (BMI) of 40 kg/m2 or greater and those with a BMI between 35 and 40 kg/m2 and a major medical comorbidity in order to: Support weight loss Treat or prevent obesity-related comorbidities (e.g., diabetes,

hypertension, cardiovascular disease, obstructive sleep apnea)

The most common types of bariatric surgery include: Laparoscopic adjustable gastric banding (LAGB) Roux-en-Y gastric bypass (RYGB) Sleeve gastrectomy Biliopancreatic diversion with duodenal switch (BPD/DS)

Background:Definition and Types of Bariatric Surgery

Buchwald H, Estok R, Fahrbach K, et al. Am J Med. 2009 Mar;122(3):248-256. PMID: 19272486. Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82.Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.

Studies show that bariatric surgery causes significant weight loss and is more effective at improving diabetes in the short term (up to 2 years) than nonsurgical interventions (diet, exercise, other behavioral interventions, and medications).

Diabetes improvement starts rapidly after surgery, before significant weight loss has occurred.

The mechanism for postoperative metabolic improvements has not been fully elucidated and may be, in part, independent of weight loss.

This suggests that bariatric surgery may improve metabolic comorbidities even in patients who are not morbidly obese.

Background: Role of Bariatric Surgery in Managing Obesity and Associated Metabolic Conditions

Buchwald H, Estok R, Fahrbach K, et al. Am J Med. 2009 Mar;122(3):248-256. PMID: 19272486. Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82.Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.Mingrone G, Panunzi S, De Gaetano A, et al. N Engl J Med. 2012 Mar 26;366(17):1577-85. PMID: 22449317.

In recent years, bariatric surgery has been suggested as an option for patients with lower body mass indexes (BMIs; at least 30 kg/m2 but less than 35 kg/m²) as a way to treat diabetes and other metabolic conditions.

However, there is a lack of consensus regarding the minimum BMI requirement.

Additionally, there remain uncertainties about the comparative effectiveness of different bariatric surgical procedures, especially in the long term.

This review assessed the relative risks and benefits of the various surgical and conventional approaches to treating diabetes or impaired glucose tolerance in patients with a BMI of 30.0 to 34.9 kg/m².

Background: Uncertainties Related to the Role of Bariatric Surgery in Patients With Lower BMIs and Metabolic Conditions

International Diabetes Federation Taskforce on Epidemiology and Prevention. Available at www.idf.org/webdata/docs/IDF-Position-Statement-Bariatric-Surgery.pdf. Accessed July 2013. Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82.Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.U.S. Food and Drug Administration. Available at www.fda.gov/NewsEvents/Newsroom/ PressAnnouncements/ucm245617.htm. Accessed July 2013.

Topics are nominated through a public process, which includes submissions from health care professionals, professional organizations, the private sector, policymakers, members of the public, and others.

A systematic review of all relevant clinical studies is conducted by independent researchers, funded by AHRQ, to synthesize the evidence in a report summarizing what is known and not known about the select clinical issue. The research questions and the results of the report are subject to expert input, peer review, and public comment.

The results of these reviews are summarized into Clinician Research Summaries and Consumer Research Summaries for use in decisionmaking and in discussions with patients.

The Research Summaries and the full report, with references for included and excluded studies, are available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm

Agency for Healthcare Research and Quality (AHRQ) Comparative Effectiveness Review (CER) Development


Key Question 1. What does the evidence show regarding the comparative effectiveness of bariatric surgery for treating adult patients with a body mass index (BMI) of 30.0 to 34.9 kg/m² and metabolic conditions, including diabetes? Are certain surgical procedures more effective than others (laparoscopic adjustable gastric banding, gastric bypass, or sleeve gastrectomy)?

Key Question 2. What does the evidence show regarding the comparative effectiveness of bariatric surgery versus conventional nonsurgical therapies for treating adult patients with a BMI of 30.0 to 34.9 kg/m² and metabolic conditions?

Clinical Questions Addressed by This Comparative Effectiveness Review (1 of 3)



Key Question 3. What are the potential short-term adverse effects and/or complications associated with bariatric surgery for treating adult patients with a body mass index (BMI) of 30.0 to 34.9 kg/m² who have metabolic conditions?

Key Question 4. Does the evidence show racial and demographic disparities with regard to potential benefits and harms associated with bariatric surgery for treating adult patients with a BMI of 30.0 to 34.9 kg/m² and metabolic conditions? What other patient factors (social support, counseling, preoperative weight loss, and compliance with recommended treatment) are related to successful outcomes?


Key Question 5. What does the evidence show regarding long-term benefits and harms of bariatric surgery for treating adult patients with a body mass index of 30.0 to 34.9 kg/m² and who have metabolic conditions? How do the long-term benefits and harms of bariatric surgery compare to short-term outcomes (within 1 year after surgery)?



The strength of evidence was classified into four broad categories:

Rating the Strength of Evidence From the Comparative Effectiveness Review


Bariatric surgery is an effective treatment for weight-control and glucose-control outcomes in patients with diabetes and impaired glucose tolerance in the short term (up to 2 years). The strength of evidence varies depending on the bariatric surgical procedure used:

Laparoscopic adjustable gastric banding, Roux-en-Y gastric bypass, or sleeve gastrectomy

Strength of Evidence: Moderate

Biliopancreatic diversion with duodenal switch

Strength of Evidence: Low

Evidence for the Benefits of Bariatric Surgery in Adults With Metabolic Conditions and a BMI of 30.0 to 34.9 kg/m2 (1 of 3)


BMI = body mass index

In patients with diabetes or impaired glucose tolerance who have undergone bariatric surgery, improvements in glucose control outcomes can be measured as early as 1 month after surgery; however, this effect is not seen in all patients.


At 1 year after bariatric surgery, decreases in both weight and hemoglobin A1c are greater than typically achieved in studies of diet, exercise, or other behavioral interventions (please see the tables in the next two slides for details).



Evidence for the Benefits of Bariatric Surgery in Adults With Metabolic Conditions and a BMI of 30.0 to 34.9 kg/m2 (2 of 3)

Outcomes of Surgical and Nonsurgical Treatments in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2: Weight and Hemoglobin A1c

Outcomes (at 1 year

unless otherwise specified)

Bariatric Surgery*Behavioral Changes**

Medications**

Weight • A decrease in BMI of 5 to 7 kg/m2 (about 15 to 20 kg for someone whose height is 5 feet 6 inches)

• Weight loss of 2.8 kg with diet, exercise, and behavioral interventions versus usual care

• Weight gain from 1 to 5 kg with some drugs†

• Weight loss of 2.8 kg with GLP-1R agonists

• No weight change with metformin

Hemoglobin A1c

(percentageof total hemoglobin)

• A decrease of 2.6 to 3.7 percentage points



* Data are primarily from observational studies and a few RCTs. ** Data are almost entirely from systematic reviews and RCTs. † These oral medications include second-generation sulfonylureas, biguanides, thiazolidinediones, meglitinides, and alpha-glucosidase inhibitorsAbbreviations: BMI = body mass index; GLP-1R = glucagon-like peptide receptor 1; RCT = randomized controlled trial


Outcomes of Surgical and Nonsurgical Treatments in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2: Other Metabolic Outcomes

Outcomes (at 1

year unless

otherwise specified)

Bariatric Surgery* Behavioral Changes** Medications**

Other metabolic outcomes

• Significant improvements in diastolic blood pressure, lipids, and metabolic syndrome at 2 years were reported in one RCT. Prevalence of metabolic syndrome decreased by 34.8 percent.

• Significant decreases in hypertension and cholesterol medications at 1 year were reported in another RCT.

• Fasting blood glucose was reported to have improved significantly in two RCTs.

• Improvements in blood pressure and lipids at 1 or 2 years were also reported in observational studies. However, outcomes reporting was inconsistent.

• Diet improved fasting glucose (a reduction of 1.3–36.6%) and triglycerides (a reduction of 11.3–58.9%).

• The PREDIMED study conducted in Spain found that a Mediterranean diet reduced metabolic syndrome prevalence by 13.7 percent at 1 year.

• The Finnish Diabetes Prevention Study found that behavioral change reduced metabolic syndrome prevalence at 3.9 years (OR = 0.62).

• Most medications had minimal effects on systolic and diastolic blood pressures, with changes less than 5 mmHg.

• Metformin and second-generation sulfonylureas generally decreased LDL-cholesterol levels.

* Data are primarily from observational studies and a few RCTs. ** Data are almost entirely from systematic reviews and RCTs.Abbreviations: BPD = biliopancreatic diversion; LDL = low-density lipoprotein; OR = odds ratio; PREDIMED = PREvencio’n con DIeta MEDiterra’nea (in Spanish); RCT = randomized controlled trial; RYGB = Roux-en-Y gastric bypass

Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82. Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.

Outcomes of Surgical and Nonsurgical Treatments in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2: Prevention of Diabetes

Outcomes (at 1

year unless otherwise specified)

Bariatric Surgery*

Behavioral Changes** Medications**

Prevention of diabetes

• Data unavailable.

• The U.S. Diabetes Prevention Program (DPP) found diabetes incidence in 10 years reduced by 34 percent by behavioral change versus placebo.

• The DPP found diabetes incidence in 10 years reduced by 18 percent in the metformin group versus placebo.

* Data are primarily from observational studies and a few randomized controlled trials (RCTs). ** Data are almost entirely from systematic reviews and RCTs.


Several studies report improvements in hypertension and cholesterol at 1 year after bariatric surgery.


The evidence is insufficient to permit conclusions about the effectiveness of bariatric surgery, when compared with other interventions, regarding these outcomes: Continued weight loss or weight maintenance in the long

term (more than 2 years) Hemoglobin A1c ˜˜™levels in the long term (more than 2

years) Prevention of diabetes Microvascular and macrovascular outcomes

Strength of Evidence: Insufficient Maglione MA, Gibbons MM, Livhits M, et al. AHRQ Comparative Effectiveness Review No. 82.Available at www.effectivehealthcare.ahrq.gov/weight-loss-surgery.cfm.

Evidence for the Benefits of Bariatric Surgery in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2

Complications of laparoscopic adjustable gastric banding reported in more than one study include: ††Band slippage (2.3%) Port or tube problems and band erosion (2%) Postsurgical pouch dilation (5.4%) Reflux/hiatal hernia (2.7%)

†Strength of Evidence: Low Complications of Roux-en-Y gastric bypass reported in more than

one study include: Stricture (5%) Ulcers (9%) Incisional hernias (4.5%) Wound infections (4.3%) ˜™™„„

˜™™Strength of Evidence for All Bariatric Procedures: Low

Evidence for the Adverse Effects of Bariatric Surgery in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2 (1 of 2)


The surgical complication rates for sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB) are similar. However, the types of complications observed with these two procedures might vary.


Although the reported rates of mortality are low in this population (rate of mortality is 0.48% for laparoscopic adjustable gastric banding and 0.0 percent for gastric sleeve, RYGB, and biliopancreatic diversion), studies are too limited to accurately predict risks.

„Strength of Evidence: Low

The evidence is insufficient to evaluate adverse effects of bariatric surgery in the long term (beyond 2 years) for patients with diabetes or impaired glucose tolerance.

Strength of Evidence: Insufficient

Evidence for the Adverse Effects of Bariatric Surgery in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2 (2 of 2)


The evidence is insufficient to permit conclusions about how the effectiveness and safety of bariatric surgical procedures compare with each other as treatment for diabetes or impaired glucose tolerance (IGT) in patients with a BMI of 30.0 to 34.9 kg/m2.

„„Strength of Evidence: Insufficient

The evidence is insufficient to know if racial or demographic disparities affect the potential benefits and adverse effects of bariatric surgery in patients with a BMI of 30.0 to 34.9 kg/m2 and diabetes or IGT.


The evidence is insufficient to determine if other patient factors (social support, counseling, preoperative weight loss, or treatment compliance) are related to successful postsurgical outcomes.


Other Findings of the ComparativeEffectiveness Review


There are additional considerations that clinicians should recognize that were not the subject of the systematic review. Depending on the type of bariatric surgery, these considerations might include regular postsurgical monitoring for: Weight regain Recurrence of diabetes Nutritional deficiencies Other postsurgical complications

Bariatric Surgery in Adults With Metabolic Conditions and a Body Mass Index of 30.0 to 34.9 kg/m2: Other Considerations

Mechanick JI, Youdim A, Jones DB, et al. Surg Obes Relat Dis. 2013;9(2):159-91. PMID: 23537696.

Bariatric surgery is an effective treatment for diabetes and impaired glucose tolerance in patients with a body mass index of at least 30 but less than 35 kg/m2 who are followed up to 2 years. Weight-loss and glucose-control outcomes achieve greater

improvement than typically seen with behavioral interventions (e.g., diet, exercise).

Head-to-head comparisons are needed to determine comparative effectiveness among surgical interventions.

Conclusions (1 of 3)


The rates of short-term adverse effects (cardiovascular, respiratory, gastrointestinal, and metabolic) were low.

Reported complications of laparoscopic adjustable gastric banding include band slippage, leakage, and pouch dilation, and those reported for Roux-en-Y gastric bypass include stricture, ulcers, and rarely hemorrhage.

While not discussed in the review, it has been suggested that weight regain and recurrence of diabetes might be observed after bariatric surgery.



Despite promising short-term outcomes, very few studies of this target population have followup durations greater than 2 years.

The long-term effects of bariatric surgical procedures on major clinical endpoints in this patient population with a lower body mass index are not known.

Studies comparing surgical intervention to comprehensive care and behavioral interventions to each other are also needed to determine the relative effectiveness of these strategies in the long term.



There is a scarcity of high-quality studies for patients with a body mass index of 30.0 to 34.9 kg/m2 and metabolic comorbidities.

Very few studies had long-term followup (more than 2 years).

The effectiveness of bariatric surgery in preventing the clinical consequences of diabetes and its impact on major clinical endpoints such as cardiovascular mortality or morbidity have not been studied.

Of the 54 studies included in the comparative effectiveness review, a very limited number were conducted in the United States, making applicability of findings from studies conducted outside the United States to American patients unclear.

Gaps in Knowledge (1 of 2)


Quality-of-life and psychological outcomes after surgery were rarely reported.

Most studies were not designed to assess adverse events and reflected events reported by the surgeon or the surgical team. The rates of adverse events in these studies may, therefore, be lower than rates experienced in the wider community.

For all surgical procedures, there is concern that published studies usually come from academic medical centers. Outcomes for patients in these studies may not reflect the outcomes achieved in the wider community.

Gaps in Knowledge (2 of 2)


The possible benefits of bariatric surgery for patients with a body mass index between 30.0 and 34.9 kg/m2 and with diabetes or IGT

The possibility that the patient could be referred to a surgeon who would discuss the different types of bariatric surgery recommended for the patient

The possible adverse effects of bariatric surgery

Whether or not the specific bariatric surgery recommended for the patient would be covered by the patient's insurance and how that would impact the patient's decisionmaking

Lifestyle changes that are necessary to fully benefit from bariatric surgery

Nonsurgical treatment options for diabetes and other metabolic conditions

The expected course of the patient's diabetes with continued nonsurgical therapy

What To Discuss With Your Patients


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