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Truth and Truthiness in Surgery

The current practice of surgery is an accumulated wisdom, mixing fact, opinion and magical thinking in unknown proportions.” (Jeff Matthews).

Stephen Colbert

This provocative opening statement and a definition of truthiness from Steven Colbert opened the Crossgrove lecture at UHN by Jeff Matthews. Jeff is a Surgeon Scientist whose background includes medical school and surgical training at Harvard and hepatobiliary surgical training in Bern, Switzerland. He has been Chair of Surgery at the University of Chicago since 2006.

Jeff Matthews
Jeff Matthews

Jeff opened with an interesting Venn diagram of Plato’s notion of knowledge, located at the intersection of truth and belief.

He cited the evidence we usually rely upon - the textbook that states that 90% of febrile episodes in the first 48 hours after surgery are caused by atelectasis, and the confirmatory ritual of a chest X-ray showing atelectasis followed by a response to chest physiotherapy and incentive spirometry. “The relationship between atelectasis and fever is unsupported by clinical or experimental evidence. Atelectasis does not induce fever in animals. Spontaneous or therapeutic pneumothorax in humans is not associated with fever, and the incidence of postoperative atelectasis is similar with and without postoperative fever. Nevertheless, we are led by thought leaders and tradition to believe in this persistent myth.” (1) This and other very convincing anecdotes set the stage for a rational deconstruction of evidence-based medicine.

Q: Are antibiotics unequivocally indicated in pancreatitis?

A: Yes, according to some meta-analysis and Cochrane reports. No, according to the same sources at a different time.

Q: Is mechanical bowel preparation indicated for colorectal surgery?

A: “In three meta-analyses of nine randomized trials in over 1,500 patients, no mechanical prep was better than mechanical prep to prevent anastomotic leak, wound infection and septic and non-septic complications (2). Despite the evidence, nearly all colorectal surgeons use mechanical bowel prep.”

“John Ioannadis shows convincingly that most published research findings are false (3). The prevalence of false positives is related to emphasis on P values, flexible trial designs, data manipulation, and large scale data mining. Bias in the medical literature derives from publication bias - favouring publication of positive or hot results; time lag bias - as negative results generally follow considerably after positive ones; citation bias - because the visibility of positive studies is increased by subsequent citation; reporting bias - as authors highlight positive over negative results; and prevailing field bias - supporting entrenched opinion. Highly cited studies showing strong treatment effects are often followed later by reports of smaller effects, or contradictory findings. Only 44% are ever confirmed, 24% are never challenged.

Graphic diagram


Truth is somewhat subjective as different frames of reference are used by different observers of the same events, and different relative weight assigned to the details of the observation results in selective assembly of information to reconstruct past events. This is the so-called Rashomon effect, illustrated in Kurosawa’s classic motion picture in which four individual witnesses describe a crime in four mutually contradicting ways.

“Knowledge is filtered through the imperfect lens of human perception, resulting in cognitive distortion. Our biases influence our perceptions. Cognitive distortion can be broken into group-think, professional deformation (how members of our own profession would look at the situation without the broader view, focusing too much on one aspect of an event), framing - leading to conclusions that are highly dependent on how the data are presented, and confirmation bias- searching for information in a way that confirms our preconceptions and vested interests. Surgeons are susceptible to cognitive distortion and bias because of our hierarchical organizational structure, the influence of our mentors, the narrative style of our rationalizations, (particularly in the culture of the morbidity and mortality conference), a predilection for linear causality, i.e. what chain of events is decided upon as the cause of an action or decision, and belief in ourselves and our results for economic and reputational reasons.

“Mechanisms to repair or compensate for cognitive distortion include: rules of thumb (heuristics), multidisciplinary teams to broaden the view of decision makers, and decision support tools such as standardized nomenclature, classifications of clinical presentations, risk stratification, scoring systems, algorithms and decision trees. Many protocols and algorithms, however, can create a false aura of certainty and an illusion of mathematical precision. Though we can quantify the predicted mortality for a particular operation for a particular disease, when it comes to the application in a particular patient, there are multiple qualitative and subjective factors which heavily influence the actual outcome. What are this patient’s comorbidities, anatomic circumstances, family circumstances, value system, local institutional resources, comorbidities? Personalized medicine is a current favourite belief system, promising a path to precise biasfree decision-making. Multidimensional large scale data sets promise early detection, improved prognostic prediction, and the development of precisely tailored therapy. The reality is that scientific reductionism and the acquisition of data is outpacing methodology, and the exaggerated potential for individualized care is leading to a paradoxical depersonalization of medicine.”

Professor Matthews closed with a statement that evidence- based medicine is an important concept, but it is insufficient to encompass all forms of knowledge needed for good care. Tacit knowledge (described by the Hungarian polymath Michael Polanyi, who famously said: “We know more than we can tell”) is the knowledge gained in a local context with traditions and experiences that are not universally shared, and cannot be dissociated from unconscious and subjective elements. “The meaning between words, intuition and judgment are part of the concept of tacit knowledge.”

“In surgical education that puts so much emphasis on facts, there should be a focus on uncertainty. Learning to make decisions with incomplete information, ability to recognize false precision, over simplification, overconfidence and drift toward trying to be the decisive surgeon.

“In summary, truth and truthiness inevitably coexist. Evidence is allusive and fluid. Knowledge is inseparable from bias and experience, and evidence-based medicine is an incomplete epistemology that inadequately accounts for the complexity and nuances of clinical decision-making.” This stimulating lecture closed with a delightful quote from Nobel laureate and University of Chicago Professor of Physics Enrico Fermi. After hearing a lecture by Niels Bohr, Fermi said: “Before I came here I was confused about the subject. Having listened to your lecture, I am still confused, but on a higher level.”

Tom Waddell asked if this de-emphasis on the factual and rational basis of surgical practice is a call for a return to the apprentice model. Matthews answered that longer exposure to surgical decision-making, for example during a general surgery residency prior to entering a specialty like plastic surgery has led to better performance. The exact content of what was learned in that preparation is hard to specify.

M.M.

1. I have reported the lecture here from my notes. Quotation marks are used to convey a sense of participation to the reader. They should not be taken as evidence of an accurate record of what was said [Ed.]

2. Slin, K. British Journal of Surgery, 2004, vol. 91, pp 1125- 30

3. PLOS Medicine 2005, vol. 2, pp 696-701




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