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

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

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

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  • 1. Cognitive Biases in Bariatric Surgery: The Strange Case of the Mini-Gastric Bypass Dr. Rutledge, DrR@clos.net
  • 2. First International ConsensusConference on the Mini-Bypass / One Anastomosis Bypass Paris 2012 October 18-19 Email DrR@CLOS.Net
  • 3. Dr. Rutledge, DrR@clos.net
  • 4. Surgeons 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 Whats 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 Whats Going On Here?P.S. Maybe we just got some poor Non-MGB surgeons to fill out the survey Email me: DrR@CLOS.netMaybe you can help bring up their score!
  • 26. HUMAN DECISION MAKINGERRORSRecent 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 ones 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 ones 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 someones evaluation of the logical strength of an argument • Experimenters 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 ones 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 ones 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 ones 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 thatconfirms preconceptions) •Herd Behavior (group think overriderational) •“Reptilian Brain”Amygdala is part"impulsive," primitive system that triggers
  • 31. PRIMITIVE RESPONSESYSTEMSMODIFY RISKASSESSMENT
  • 32. THE REPTILIAN BRAIN:EMOTION & DECISION MAKING •Primitive, Impulsive •Irrational decision-making •System I: Instinct •Amygdala: Interfereswith the Frontal lobe •Rational LogicalThinking: •System II: Deliberative •Frontal Lobe
  • 33. IRRATIONAL ILLOGICALTHINKING:Cognitive Bias •We think we are smarterthan we really are •Examples to numerous tomention •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"
  • 34. IRRATIONAL ILLOGICALTHINKING:Sample Cognitive Biases •CONFIRMATION BIASContrary Evidence =>Maintains or strengthenspresent beliefs •Overconfidencein present beliefs;"Group Think" •Poor Decision Making •Especially Present in Organizations, Military,Political & Social Groups
  • 35. 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 / 20years risk of gastric cancer •Bowel Obstruction frominternal hernia +16% in 5years
  • 36. SURGERYHISTORY OF POORDECISIONSJOSEPH LISTER:AMERICANSURGEONS DELAYEDADOPTION OFANTISEPSIS 10 YEARS
  • 37. REPTILIAN BRAIN POOR DECISION MAKING • •1867Lister publishedantisepsis paper: Dr. Gross; Gross Clinic 1875
  • 38. HUMAN DECISION MAKING ERRORS:EXPECTED, NOT RARE •Realize Fallibility ofHuman Decision Making •Humility •Socratic Questioning ofAssumptions •Search for Logical &Rational Decision Making
  • 39. THE PROBLEM •Obesity Epidemic •History of Failure of BariatricSurgical 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