Bariatric Surgery: What the Generalist Needs to Know

Anne Schafer, MDChief of Endocrinology & Metabolism, SFVAHCS

Associate Professor of Medicineand of Epidemiology & Biostatistics, UCSF

DisclosuresResearch support:▫ Investigator-initiated research grant from Amgen▫ Dietary supplements for research studies

donated by Bariatric Advantage and Tate & Lyle

Objectives• Describe the effects of bariatric surgery on

cardio-metabolic outcomes and mortality

• Identify basic eligibility criteria for surgery

• Apply recommendations for post-op medical management, monitoring

Case 146 y.o. woman w/ severe obesity, type 2 DM, HTN, GERD•Wt increased from 240 to 280 lbs over

last 10 years (BMI 40 to 46 kg/m2)• Lost 20 lbs with Weight Watchers then

regained 10 lbs•Walks 30 min 3 times/week

Weight loss surgery?

61 y.o. man with obesity, type 2 diabetes• 423375 lbs (BMI 5448 kg/m2)•Roux-en-Y gastric bypass surgery 240 lbs (BMI 31) Insulin discontinued

•New low back pain

Why did he fracture?

Case 2

• 38% of US adults (Men 35%, women 40%)1

▫ Stage 3 obesity (BMI ≥40 kg/m2): 7.7%Men 5.5%, women 9.9%

• Lifestyle changes usually do not result in clinically meaningful and sustained wt loss▫ Rarely of the magnitude needed for those with

extreme obesity1Flegal, JAMA 2016

Obesity is an important and growing public health problem

Wadden, N Engl J Med 2011

Almost 10-fold increase in operations performed annually in the early 2000s

• 25,000 operations in 1998 220,000 in 20091

1Buchwald, Obes Surg 2009

Growing demand for bariatric surgery

DeMaria, N Engl J Med 2007

Biliopancreatic diversion with

duodenal switch

Adjustable gastric band

Malabsorptive Restrictive

DeMaria, N Engl J Med 2007

Roux-en-Y gastric bypass

(RYGB)

Sleeve gastrectomy

Sjostrom, JAMA 2012

Comparative weight loss outcomes

Control

LAGB

VBG

RYGB

Maciejewski, JAMA Surg 2016

Comparative weight loss outcomes

LAGB

Sleeve

RYGB

• Completely resolved in 77%, and resolved or improved in 86%1

▫ 84% resolved after RYGB, 48% after gastric banding

• Resolution often occurs days after RYGB, even before marked weight loss2

• Weight-dependent and weight-independent mechanisms

1Buchwald, JAMA 2004; 2Rubino, Ann Surg 2004

Type 2 diabetes

• All procedures: Weight loss▫Weight Insulin resistance

• RYGB: Additional endocrine effects1-3

▫ GLP-1 Insulin secretion• “Incretin effect”

▫ Ghrelin, PYY Hunger, satiety

1Rubino, Ann Surg 2004; 2Laferrere, JCEM 2008; 3Cummings, JCEM 2004

Why does diabetes improve/resolve?

1. More diabetes remission with RYGB (75%) and BPD (95%) than conventional medical tx (0%) at 2 yrs1

2. 150 obese pts w/ uncontrolled DM underwent intensive medical therapy +/-RYGB or sleeve gastrectomy2

▫ 12% (medical tx alone) vs. 42% (RYGB) vs. 37% (sleeve) had A1c <6.0% at 12 months

1Mingrone, NEJM 2012; 2Schauer, NEJM 2012

Diabetes RCTs

Schauer, NEJM 2012

Intensive medical therapy

Sleeve gastrectomyRoux-en-Y gastric bypass

Intensive medical therapy

Sleeve gastrectomyRoux-en-Y gastric bypass

HbA1c

# DMMeds

• SBP and DBP as early as 1 week post-op1

▫ Weight-independent as well as -dependent mechanisms

• HTN resolves or improves in 79%2

• Complete resolution after 3 yrs in 38% of RYGB pts and 17% of LAGB pts3

1Ahmed, Obes Surg 2009; 2Buchwald, JAMA 2004; 3Courcoulas, JAMA 2013

Hypertension

• Hypercholesterolemia improves in 71%, hypertriglyceridemia in 82%1

• Resolution of dyslipidemia after 3 yrs in 62% of RYGB pts and 27% of LAGB pts2

1Buchwald, JAMA 2004; 3Courcoulas, JAMA 2013

Dyslipidemia

Sjostrom, JAMA 2012

• CV deaths: adjusted HR 0.47 (0.29-0.76)

Cardiovascular outcomes: Swedish Obesity Subjects Study

Fatal CV Events Total CV Events

Sjostrom, JAMA 2012

Cardiovascular outcomes: Swedish Obesity Subjects Study

No interaction with baseline BMI

Stronger CV effect if high baseline insulin level

• 29% reduction in risk after 10 yearsSjostrom, NEJM 2007

Mortality: Swedish Obesity Subjects

Adams, NEJM 2007

Mortality: Utah gastric bypass study

• Covariate-adjusted mortality: 40% lower in surgery group

• Death rates for specific causes:• Lower for CVD, diabetes, cancer

• CVD: HR 0.50 (95% CI 0.36-0.69)• Higher for suicide/accidents

Mortality: Stronger protective effect in patients with diabetes

Lent, Diabetes Care 2017

Objectives• Describe the effects of bariatric surgery on

cardio-metabolic outcomes and mortality

• Identify basic eligibility criteria for surgery

• Apply recommendations for post-op medical management, monitoring

Case 146 y.o. woman w/ severe obesity, type 2 DM, HTN, GERD•Wt increased from 240 to 280 lbs over

last 10 years (BMI 40 to 46 kg/m2)• Lost 20 lbs with Weight Watchers then

regained 10 lbs•Walks 30 min 3 times/week

Weight loss surgery?

Typical criteria:•BMI ≥40 kg/m2, or BMI ≥35 kg/m2 with an obesity-related co-morbidity•Failure of lifestyle/medical weight control•Absence of psychological or medical contraindications

Undertreated psychiatric conditions Low likelihood of adherence to post-op requirements Poor coping strategies, lack of social support Eating disorders

Bariatric surgery: Eligibility criteria

Typical criteria:•BMI ≥40 kg/m2, or BMI ≥35 kg/m2 with an obesity-related co-morbidity•Failure of lifestyle/medical weight control•Absence of psychological or medical contraindicationsPotential exclusion criteria (varies by practice):•>400 lbs, tobacco or other substance use/abuse, CHF or pulmonary HTN not responsive to medical therapy, O2-dependent COPD, cirrhosis

Bariatric surgery: Eligibility criteria

Case 146 y.o. woman w/ severe obesity, type 2 DM, HTN, GERD•Wt increased from 240 to 280 lbs over

last 10 years (BMI 40 to 46 kg/m2)• Lost 20 lbs with Weight Watchers then

regained 10 lbs•Walks 30 min 3 times/week

Weight loss surgery?

Objectives• Describe the effects of bariatric surgery on

cardio-metabolic outcomes and mortality

• Identify basic eligibility criteria for surgery

• Apply recommendations for post-op medical management, monitoring

• Anticipate potentially abrupt decrease in insulin/oral diabetes med needs• Often, stop sulfonylureas at surgery• Decrease insulin doses• Metformin often continued• Self-monitoring and self-titration

Post-op management: Diabetes

• Anti-hypertensive medications• No preemptive D/C of agents• Monitor closely at visits and adjust

• Lipid-lowering medications• Many bariatric surgery pts will continue to

meet criteria for statin use• Caution about creating expectations that

statins will be d/c’ed post-op

Post-op management

• Oral meds: crush in initial post-op months• Avoid NSAIDs• Caution with meds dosed based on

weight (e.g., levothyroxine)• Caution about potential malabsorption of

meds

Other medication strategies

• Weight regain• Micronutrient

deficiencies• Protein deficiency• Dumping syndrome

• Gallstones• Nephrolithiasis• Acute gout• Bone loss• Hypoglycemia

Potential metabolic and nutritional complications

• Vitamin B12• Calcium, vitamin D• Iron• Thiamine• Folic acid• Vitamin A• Vitamin K; zinc; selenium; copper

MalabsorptionLess foodDifferent food

Micronutrient deficiencies

• Multivitamin• 1-2 daily (often 1 bariatric-potency chewable)

• Vitamin B12• 350-1000 mcg/day po or 1000 mcg/month IM

• Vitamin D• 3000 IU daily

• Iron• Menstruating women; take with ascorbic acid

• Calcium citrate• 1200-1500 mg elemental Ca daily from diet + Ca

citrate supplement (more for BPD/DS)

Routine supplements

Parrott, Surg Obes Relat Dis 2017

• Pre-op, q 6 months x 2 years, annually• Vitamin B12• Calcium• Intact PTH• 25(OH) vitamin D• Ferritin• Thiamine• (Folate, vitamin A, zinc, copper)

Biochemical monitoring

Heber (Endocrine Society), JCEM 2010; Mechanick (AACE/TOS/ASMBS), Surg Obes Relat Dis 2013

• Abdominal cramping, nausea, diarrhea, lightheadedness, flushing, tachycardia

• Concentrated sweets hyperosmolarity of intestinal contents influx of fluid into intestinal lumen?

• Role of gut peptides?• Perhaps 75% of gastric bypass pts• Often transient issue, early post-op period

Dumping syndrome

Heber (Endocrine Society), JCEM 2010

• Dx of hypoglycemia requires Whipple’s triad• Symptoms• Low glucose concentration• Resolution of sxs with glucose correction

Dumping vs HypoglycemiaDumping syndrome Hypoglycemia

Occurs early after eating (~30 min)

Occurs 1-3 hours postprandially

Develops in early post-op period, often resolving over time

Develops ≥1 year post-op

Patti, Lancet Diabetes Endocrinol 2016

Hypoglycemia: Potential mechanisms• Overtreatment with insulin, sulfonylurea• Postprandial insulin secretion ▫ Intestinal delivery rapid glucose▫ Incretin effect (GLP-1, GIP)▫ Islet cell mass• Non-insulin dependent mechanisms▫ Dysregulated enteroendocrine secretion▫ Altered gut microbiota▫ Bile acids

Patti, Lancet Diabetes Endocrinol 2016

simple carbs;acarbose

octreotide

diazoxide; CCBs

X

• Protein deficiency• Eat protein first; 60-120 g/d or 1.5 g/kg IBW

• Gallstones• Ursodiol, or simultaneous cholecystectomy

• Nephrolithiasis• Hydration; low oxalate diet; oral Ca; KCit

• Acute gout• Prophylactic therapy in appropriate pts

• Bone loss and fracture• Ca and vit D; consider DXA in at-risk pts

Other prevention, treatment

Heber (Endocrine Society), JCEM 2010; Mechanick (AACE/TOS/ASMBS), Surg Obes Relat Dis 2013

Objectives• Describe the effects of bariatric surgery on

cardio-metabolic outcomes and mortality

• Identify basic eligibility criteria for surgery

• Apply recommendations for post-op medical management, monitoring

1Compston, Gastroenterology 1984; 2Fish, J Surg Res 2010;3Dixon, Obesity 2007

•Gastric bypass induces abnormalities in bone metabolism▫ Early and sustained s in bone turnover▫ Decreases in bone mineral density (BMD)• Fewer data for other procedures▫ Biliopancreatic diversion: similar1

▫ Gastric band: less impact on bone2,3

Bariatric surgery and skeletal health

BMD decreases substantially

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Spine (QCT)

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Schafer, J Bone Miner Res 2015

Bone loss: Potential mechanisms

•Decreased loading• Nutritional factors▫ vitamin D and Ca intake▫ Ca absorption1,2

•Changes in fat-secreted hormones▫ estradiol▫ adiponectin• Loss of muscle mass1Cifuentes, Am J Clin Nutr 2004; 2Shapses, Am J Clin Nutr 2013

DRAMATIC! RAPID!^

+ MALABSORPTION

+ RYGB-SPECIFICNEUROHORMONALEFFECTS

Intestinal Ca absorption capacity decreases precipitously

Schafer, J Bone Miner Res 2015

Concern for early fracture-related morbidity and mortality among bariatric

surgery patients

61 y.o. man with obesity, type 2 diabetes• 423375 lbs (BMI 5448 kg/m2)•Roux-en-Y gastric bypass surgery 240 lbs (BMI 31) Insulin discontinued

•New low back pain

Why did he fracture?

Case 2

• Not taking Ca or vitamin D supplements• DXA: Total hip T-score -1.8

Ca(8.5-10.5)

Alb(3.3-5.2)

Phos(2.5-4.5)

Cr(0.6-1.3)

25OH D(30-50)

PTH (12-65)

24h Uca(100-250)

8.4 3.6 2.5 1.1 17

• Vitamin D repletion course, daily Cacarbonate and vitamin D maintenance

8.5 3.5 3.0 1.1 28 80 58

• Increased Ca intake and switched to citrate

8.4 3.7 2.8 1.3 34 144

Recommendations for bone healthCheck and replete 25(OH)D pre-opUniversal post-op supplements

• Multivitamin, calcium (dose?), vitamin DLabs q 6 mo x 2 yrs then annuallyPost-op exercise/resistance training?Monitor BMD by DXA?Pharmacologic therapy for high risk pts?

Heber (Endocrine Society), JCEM 2010; Mechanick (AACE/TOS/ASMBS), Surg Obes Relat Dis 2013

Thank you!