Cognitive Biases in Bariatric Surgery: The Strange Case of the MGB

Dr. Rutledge, [email protected]

Cognitive Biases in Bariatric Surgery: The Strange Case of the Mini-Gastric Bypass

First International Consensus Conference on the Mini-

Bypass / One Anastomosis Bypass

Paris 2012 October 18-19

Email [email protected]

Dr. Rutledge, [email protected]

Surgeon's Knowledge Contributes to Patient Outcomes

• Richardson et al., Annals of Surgery:10 September 2012

• Survey of Knowledge and analysis of patient outcomes in Nova Scotia

• 377 patients (72%) were treated by 25 surgeons

• Surgeon survey score was associated with More Adequate Lymph Node Excision, Lower Risk of Colostomy, Local Recurrence Rate and Higher Case Volume

IFSO Varianational Committee Survey

Over 100 Surgeons from Around the World:

IFSO Varianational Committee Survey

• Results (Preliminary)• Experience with 39,000 cases in

the prior year• Lap Band is a "Poor" Surgery• RNY & Sleeve Surgeons have

"lots" of leaks• MGB Surgeons Answered More

Correct than Non-MGB Surgeons

MGB Surgeons Answered More Correct than

Non-MGB Surgeons!But FIRST some other results...

The Lap Band is "Not a Very Good" Surgery

Lap Band Unlikely to Get Major Weight Loss (5%)

Lap Band GE Reflux is Common

Revision of the Band is NOT Easy

Band Failure is "Very Common" 75%

0%

25%

50%

75%

100%

Is very rare Can happen sometimes Is very Common

Failure of Lap Band

1%

24%

75%

Did you once use the band in your practice and then stop?

• Did you once use the band in your practice and then stop?

• Yes: 51% Had Been Band Surgeons and Now Have Abandoned the Band

Leaks: MGB Surgeons vs RNY Surgeons

• MGB Surgeons 52% No Leaks in Past Year(1 surgeon with 2 Leaks, Both from Sleeve, Awful experience by report)

• RNY/Sleeve Surgeons36% No Leaks in Past Year(15% had 4 Leaks Last year!)

MGB Surgeons Answered More Correct than Non-MGB Surgeons

• Q #75: "There are many large scale studies that show no increased risk of gastric cancer after Billroth II:"

• i.e.: 30 yr f/u, over 500 pts• "Risk of gastric cancer is * Not * increased

after partial gastrectomy."• Bassily R, Dept Gastroent., Victoria, Australia.J Gastroent

Hepatology. 2000 15(7):762;

• 44% Non-MGB Surgeons did not know this


• 76. I understand the difference between "Association" and "Causation"

• 12% Did know the difference


• 77. In a study from the Netherlands of 58,279 patients 162 stomach cancers were detected.

• A higher risk for stomach cancer was found for men with the lowest level of education

• (RR lowest/highest level = 2.0, p = 0.02)• i.e. Lower education = higher risk of stomach

cancer• Do you think less education "CAUSES"

stomach cancer?• 15% answered: Less Education

"Causes" Gastric Cancer


• 78. There are some studies showing a slight increased risk of gastric cancer 20-30 years after Billroth II.

• But these patients had the Billroth II overwhelmingly for Ulcer Disease and

• Ulcer and Gastric Cancer have a common etiology;

• H. Pylori.

• Only 3% Disagreed with this, 97% Agreed with this


• 79. Unoperated Gastric Ulcer patients have double the risk for Gastric Cancer:

• Am J Gastroenterology 2007 Jun;102(6):1185-91. Pub 2007 Apr 13. Long-term risk of gastric cancer by subsite in operated and unoperated patients hospitalized for peptic ulcer. Bahmanyar S, et al, Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden

• 29% Did not know this (Even though one of the relevant articles is quoted and referenced for them!)


• There are MANY more Examples...

• 82. The death rate stomach cancer in the United States has dropped from 28 to 5 per 100,000 people

• (PS This is True)

• 25.4% Did Not Know this.


• There are MANY more Examples...

• 85. I have recently reviewed the literature on gastric cancer and am very knowledgeable about the risk of gastric cancer

• 64.4% Said No, they are not very knowledgeable about the risks of Gastric Cancer!

MGB Decreases Costs/RNY Does Not

• MGB decreases Hospitalization and Costs (1)• New study: RNY Fails to Decrease Costs(2)

• 1. Int J Surg. 2007 Feb;5(1):35-40. Pub 2006 Aug 10. Hospitalization before and after mini-gastric bypass surgery.

Rutledge R.

• 2. Arch Surg. 2012 Jul 1;147(7):633-40. Health expenditures among high-risk patients after gastric bypass and matched controls. Maciejewski ML, Livingston EH, Smith VA, Kahwati LC, Henderson WG, Arterburn DE.

In Summary:MGB Surgeons Answered More Correct

than Non-MGB Surgeons

What's Going On Here?


• These are probably all good honorable men and women who care for their patients and want to the best for them

• But this survey shows that in the area of the Mini-Bypass/Billroth II/Bile Reflux and Gastric cancer

• These surgeons are woefully ignorant of basic medical information published in the medical literature?

• Even when it is referenced and quoted• Surprisingly so!

In Summary:MGB Surgeons Answered More Correct

than Non-MGB Surgeons

What's Going On Here?P.S. Maybe we just got some

poor Non-MGB surgeons to fill out

the surveyEmail me: [email protected]

Maybe you can help bring up their score!

HUMAN DECISION MAKING ERRORS

Recent Research in Psychology and Neurobiology Shows that:

The Human Brain is a Notoriously Bad Decision

Maker

Human Decision Making ErrorsVery Common Cognitive Bias

•Exaggerate Rare Events

•Downplay Common Events

•Underestimate risks taken Willingly, (car)

•Overestimate risks Beyond Control (airplane)

•We Overestimate risks Talked About

• Ambiguity effect – the tendency to avoid options for which missing information makes the probability seem "unknown."[6]

• Anchoring – the tendency to rely too heavily, or "anchor," on a past reference or on one trait or piece of information when making decisions (also called "insufficient adjustment").

• Attentional Bias – the tendency of emotionally dominant stimuli in one's environment to preferentially draw and hold attention and to neglect relevant data when making judgments of a correlation or association.

• Availability heuristic – estimating what is more likely by what is more available in memory, which is biased toward vivid, unusual, or emotionally charged examples.

• Availability cascade – a self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or "repeat something long enough and it will become true").

• Backfire effect – when people react to disconfirming evidence by strengthening their beliefs.[7]

• Bandwagon effect – the tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.

• Barnum effect - the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people.

• Base rate neglect or Base rate fallacy – the tendency to base judgments on specifics, ignoring general statistical information.[8]

• Belief bias – an effect where someone's evaluation of the logical strength of an argument is biased by the believability of the conclusion.[9]

• Bias blind spot – the tendency to see oneself as less biased than other people, or to be able to identify more cognitive biases in others than in oneself.[10]

• Choice-supportive bias – the tendency to remember one's choices as better than they actually were.[11]

• Clustering illusion – the tendency to under-expect runs, streaks or clusters in small samples of random data

• Confirmation bias – the tendency to search for or interpret information in a way that confirms one's preconceptions.[12]

• Congruence bias – the tendency to test hypotheses exclusively through direct testing, in contrast to tests of possible alternative hypotheses.

• Conjunction fallacy – the tendency to assume that specific conditions are more probable than general ones.[13]

• Conservatism or Regressive Bias – tendency to underestimate high values and high likelihoods/probabilities/frequencies and overestimate low ones. Based on the observed evidence, estimates are not extreme enough[5][14][15]

• Conservatism (Bayesian) – the tendency to belief update insufficiently but predictably as a result of new evidence (estimates of conditional probabilities are conservative)[5][16][17]

• Contrast effect – the enhancement or diminishing of a weight or other measurement when compared with a recently observed contrasting object.[18]

• Curse of knowledge – when knowledge of a topic diminishes one's ability to think about it from a less-informed perspective.

• Decoy effect – preferences change when there is a third option that is asymmetrically dominated

• Denomination effect – the tendency to spend more money when it is denominated in small amounts (e.g. coins) rather than large amounts (e.g. bills).[19]

• Distinction bias – the tendency to view two options as more dissimilar when evaluating them simultaneously than when evaluating them separately.[20]

• Duration neglect – the neglect of the duration of an episode in determining its value

• Empathy gap – the tendency to underestimate the influence or strength of feelings, in either oneself or others.

• Endowment effect – the fact that people often demand much more to give up an object than they would be willing to pay to acquire it.[21]

• Essentialism – categorizing people and things according to their essential nature, in spite of variations.[22]

• Exaggerated expectation – based on the estimates, real-world evidence turns out to be less extreme than our expectations (conditionally inverse of the conservatism bias).[5][23]

• Experimenter's or Expectation bias – the tendency for experimenters to believe, certify, and publish data that agree with their expectations for the outcome of an experiment, and to disbelieve, discard, or downgrade the corresponding weightings for data that appear to conflict with those expectations.[24]

• False-consensus effect - the tendency of a person to overestimate how much other people agree with him or her.

• Functional fixedness - limits a person to using an object only in the way it is traditionally used

• Focalism - the tendency to rely too heavily, or "anchor," on a past reference or on one trait or piece of information when making decisions.

• Focusing effect – the tendency to place too much importance on one aspect of an event; causes error in accurately predicting the utility of a future outcome.[25]

• Forer effect - the observation that individuals will give high accuracy ratings to descriptions of their personality that supposedly are tailored specifically for them, but are in fact vague and general enough to apply to a wide range of people. This effect can provide a partial explanation for the widespread acceptance of some beliefs and practices, such as astrology, fortune telling, graphology, and some types of personality tests.

Irrational Illogical Thinking (Page 1 of 10)Decision-Making Errors Cognitive Biases

Example Cognitive Biases

• Anchoring – the tendency to rely too heavily, or "anchor," on a past reference or on one trait or piece of information when making decisions (also called "insufficient adjustment").

• Attentional Bias – the tendency of emotionally dominant stimuli in one's environment to preferentially draw and hold attention and to neglect relevant data when making judgments of a correlation or association.

• Availability heuristic – estimating what is more likely by what is more available in memory, which is biased toward vivid, unusual, or emotionally charged examples.

• Availability cascade – a self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or "repeat something long enough and it will become true").

• Backfire effect – when people react to disconfirming evidence by strengthening their beliefs.[7]

Irrational Illogical Thinking Decision-Making Errors: Cognitive Bias•Example Cognitive Biases

•Confirmation Bias (favor information that confirms preconceptions)

•Herd Behavior (group think override rational)

•“Reptilian Brain”Amygdala is part "impulsive," primitive system that triggers emotional override rational thinking

PRIMITIVE RESPONSE SYSTEMSMODIFY RISK ASSESSMENT

THE REPTILIAN BRAIN:EMOTION & DECISION MAKING

•Primitive, Impulsive

•Irrational decision-making

•System I: Instinct

•Amygdala: Interferes with the Frontal lobe

•Rational Logical Thinking:

•System II: Deliberative

•Frontal Lobe

IRRATIONAL ILLOGICAL THINKING:Cognitive Bias

•We think we are smarter than we really are

•Examples to numerous to mention

•One example:

•The Roll of the Dice andthe Judges

•Dice rolled before sentencing Criminals in Israel

•# on the Dice affected the sentence handed down!

•"Anchoring bias"

IRRATIONAL ILLOGICAL THINKING:Sample Cognitive Biases

•CONFIRMATION BIASContrary Evidence =>Maintains or strengthens present beliefs

•Overconfidence in present beliefs; "Group Think"

•Poor Decision Making

•Especially Present in Organizations, Military, Political & Social Groups

REPTILIAN BRAIN (System I) POOR DECISIONSFEAR LEADS TO JUDGMENT ERRORS

•Errors in Risk Assessment

•Death Airplane Crash

•Death Car Crash

•1 in 1,000 patient / 20 years risk of gastric cancer

•Bowel Obstruction from internal hernia +16% in 5 years

SURGERYHISTORY OF POOR DECISIONS

JOSEPH LISTER:

AMERICAN SURGEONS DELAYED ADOPTION OF ANTISEPSIS 10 YEARS

REPTILIAN BRAINPOOR DECISION MAKING

••1867

Lister published antisepsis paper:

Dr. Gross; Gross Clinic 1875

HUMAN DECISION MAKING ERRORS: EXPECTED, NOT RARE

•Realize Fallibility of Human Decision Making

•Humility

•Socratic Questioning ofAssumptions

•Search for Logical & Rational Decision Making

THE PROBLEM

•Obesity Epidemic

•History of Failure of Bariatric Surgical Procedures

•Selecting the “Ideal / BEST” Bariatric Surgical Procedure

The Mini-Gastric Bypass is an Excellent Operation with Results Reported on Thousands

of Patients Over the Past 10-15 years

• Survey Shows:• Short, Simple, Effective, Durable,• 30 min Operation with 1 day Hospital Stay• Lower Leak rate than Sleeve or RNY• Better / Best Weight Loss• Leaks easily identified and easily managed• Easily Reversible, Revisable• Marginal Ulcer / Gastritis (Bile & Acid Peptic)

= RNY Rate of marginal ulcer• Gastric Cancer is Low, no more common in

BII than in people that eat Hot Dogs/Salami or other processed meats

The Mini-Gastric Bypass is an Excellent Operation with Results Reported on Thousands

of Patients Over the Past 10-15 years

• Survey Shows:• Surgeons that Reject the MGB

are routinely and repeatedly found to answer questions about gastric cancer, the Billroth II, etc. incorrectly much more often than MGB Surgeons

• 2/3 explicitly state they are not very knowledgeable about Gastric Cancer

• These Errors May be the Result of Unrecognized Cognitive Biases