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

1. Cognitive Biases in Bariatric Surgery: The
Strange Case of the
Mini-Gastric Bypass
Dr. Rutledge, DrR@clos.net

2. First International Consensus
Conference on the Mini-Bypass / One
Anastomosis Bypass
Paris 2012 October 18-19
Email DrR@CLOS.Net

3. Dr. Rutledge, DrR@clos.net

4. 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

5. IFSO Varianational Committee Survey
Over 100 Surgeons from Around the World:

6. 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

7. MGB Surgeons Answered More Correct than
Non-MGB Surgeons!
But FIRST some other results...

8. The Lap Band is "Not a Very Good" Surgery

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

10. Lap Band GE Reflux is Common

11. Revision of the Band is NOT Easy

12. Band Failure is "Very Common" 75%

13. 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

14. 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 Surgeons
36% No Leaks in Past Year
(15% had 4 Leaks Last year!)

15. 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

16. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 76. I understand the difference
between "Association" and
"Causation"
• 12% Did know the difference

17. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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

18. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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

19. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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!)

20. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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.

21. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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!

22. 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.

23. In Summary:
MGB Surgeons Answered More Correct
than Non-MGB Surgeons
What's Going On Here?

24. MGB Surgeons Answered More Correct than
Non-MGB Surgeons
• 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!

25. 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
survey
Email me: DrR@CLOS.net
Maybe you can help bring up their
score!

26. HUMAN DECISION MAKING
ERRORS
Recent Research in Psychology
and Neurobiology Shows that:
The Human Brain is a
Notoriously Bad Decision
Maker

27. Human Decision Making Errors
Very Common Cognitive Bias
•Exaggerate Rare Events
•Downplay Common Events
•Underestimate risks taken Willingly, (car)
•Overestimate risks Beyond Control
(airplane)

28. Irrational Illogical Thinking (Page 1 of
10)
•
Decision-Making Errors Cognitive
Ambiguity effect – the tendency to avoid options for which missing information makes the
probability seem "unknown."[6]
• Contrast effect – the enhancement or diminishing of a weight or other
measurement when compared with a recently observed contrasting object.[18]
Biases
• Anchoring – the tendency to rely too heavily, or "anchor," on a past reference or on one • Curse of knowledge – when knowledge of a topic diminishes one's ability to
trait or piece of information when making decisions (also called "insufficient adjustment"). think about it from a less-informed perspective.
• Attentional Bias – the tendency of emotionally dominant stimuli in one's environment to • Decoy effect – preferences change when there is a third option that is
preferentially draw and hold attention and to neglect relevant data when making asymmetrically dominated
judgments of a correlation or association. • Denomination effect – the tendency to spend more money when it is
•
denominated in small amounts (e.g. coins) rather than large amounts (e.g.
Availability heuristic – estimating what is more likely by what is more available in memory,
bills).[19]
which is biased toward vivid, unusual, or emotionally charged examples.
• Distinction bias – the tendency to view two options as more dissimilar when
• Availability cascade – a self-reinforcing process in which a collective belief gains more evaluating them simultaneously than when evaluating them separately.[20]
and more plausibility through its increasing repetition in public discourse (or "repeat
• Duration neglect – the neglect of the duration of an episode in determining its
something long enough and it will become true").
value
• Backfire effect – when people react to disconfirming evidence by strengthening their • Empathy gap – the tendency to underestimate the influence or strength of
beliefs.[7] feelings, in either oneself or others.
• Bandwagon effect – the tendency to do (or believe) things because many other people do • Endowment effect – the fact that people often demand much more to give up
(or believe) the same. Related to groupthink and herd behavior. an object than they would be willing to pay to acquire it.[21]
• Barnum effect - the observation that individuals will give high accuracy ratings to • Essentialism – categorizing people and things according to their essential
descriptions of their personality that supposedly are tailored specifically for them, but are nature, in spite of variations.[22]
in fact vague and general enough to apply to a wide range of people. • Exaggerated expectation – based on the estimates, real-world evidence turns
• Base rate neglect or Base rate fallacy – the tendency to base judgments on specifics, out to be less extreme than our expectations (conditionally inverse of the
ignoring general statistical information.[8] conservatism bias).[5][23]
• Belief bias – an effect where someone's evaluation of the logical strength of an argument • Experimenter's or Expectation bias – the tendency for experimenters to
is biased by the believability of the conclusion.[9] believe, certify, and publish data that agree with their expectations for the
• Bias blind spot – the tendency to see oneself as less biased than other people, or to be
outcome of an experiment, and to disbelieve, discard, or downgrade the
corresponding weightings for data that appear to conflict with those
able to identify more cognitive biases in others than in oneself.[10] expectations.[24]
• Choice-supportive bias – the tendency to remember one's choices as better than they • False-consensus effect - the tendency of a person to overestimate how much
actually were.[11] other people agree with him or her.
• Clustering illusion – the tendency to under-expect runs, streaks or clusters in small • Functional fixedness - limits a person to using an object only in the way it is
samples of random data traditionally used
• Confirmation bias – the tendency to search for or interpret information in a way that • Focalism - the tendency to rely too heavily, or "anchor," on a past reference or
confirms one's preconceptions.[12] on one trait or piece of information when making decisions.
• Congruence bias – the tendency to test hypotheses exclusively through direct testing, in • Focusing effect – the tendency to place too much importance on one aspect of
contrast to tests of possible alternative hypotheses. an event; causes error in accurately predicting the utility of a future outcome.
• Conjunction fallacy – the tendency to assume that specific conditions are more probable [25]
than general ones.[13] • Forer effect - the observation that individuals will give high accuracy ratings to
• Conservatism or Regressive Bias – tendency to underestimate high values and high descriptions of their personality that supposedly are tailored specifically for
likelihoods/probabilities/frequencies and overestimate low ones. Based on the observed them, but are in fact vague and general enough to apply to a wide range of
evidence, estimates are not extreme enough[5][14][15] people. This effect can provide a partial explanation for the widespread
• Conservatism (Bayesian) – the tendency to belief update insufficiently but predictably as a acceptance of some beliefs and practices, such as astrology, fortune telling,
result of new evidence (estimates of conditional probabilities are conservative)[5][16][17] graphology, and some types of personality tests.

29. Example Cognitive Biases
• Anchoring – the tendency to rely
too heavily, or "anchor," on a past • Availability cascade – a self-
reference or on one trait or piece reinforcing process in which a
of information when making
collective belief gains more
decisions (also called "insufficient
adjustment").
and more plausibility through
•
its increasing repetition in
Attentional Bias – the tendency
of emotionally dominant stimuli in public discourse (or "repeat
one's environment to something long enough and it
preferentially draw and hold will become true").
attention and to neglect relevant • Backfire effect – when
data when making judgments of a people react to disconfirming
correlation or association.
evidence by strengthening
• Availability heuristic – their beliefs.[7]
estimating what is more likely by
what is more available in memory,
which is biased toward vivid,
unusual, or emotionally charged
examples.

30. 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

31. PRIMITIVE RESPONSE
SYSTEMSMODIFY RISK
ASSESSMENT

32. 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

33. 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 and
the Judges
•Dice rolled before sentencing Criminals in Israel
•# on the Dice affected the sentence handed down!
•"Anchoring bias"

34. IRRATIONAL ILLOGICAL
THINKING:
Sample Cognitive Biases
•CONFIRMATION BIAS
Contrary Evidence =>
Maintains or strengthens
present beliefs
•Overconfidence
in present beliefs;
"Group Think"
•Poor Decision Making
•Especially Present in Organizations, Military,
Political & Social Groups

35. REPTILIAN BRAIN (System I)
POOR DECISIONS
FEAR 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

36. SURGERY
HISTORY OF POOR
DECISIONS
JOSEPH LISTER:
AMERICAN
SURGEONS DELAYED
ADOPTION OF
ANTISEPSIS 10 YEARS

37. REPTILIAN BRAIN
POOR DECISION MAKING
•
•1867
Lister published
antisepsis paper:
Dr. Gross; Gross Clinic 1875

38. HUMAN DECISION MAKING ERRORS:
EXPECTED, NOT RARE
•Realize Fallibility of
Human Decision Making
•Humility
•Socratic Questioning of
Assumptions
•Search for Logical &
Rational Decision Making

39. THE PROBLEM
•Obesity Epidemic
•History of Failure of Bariatric
Surgical Procedures
•Selecting the “Ideal / BEST”
Bariatric Surgical Procedure

40. 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

41. 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