Transcript: Evidence-Based Medicine or Evidence-Biased?
Dr. Esselstyn’s landmark study showing even advanced triple vessel coronary artery disease could be reversed with a plant-based diet has been criticized for being such a small study, but the reason we’re used to seeing such large studies is they typically show such small effects. Drug manufacturers may need to study 7,000 people in order to show a barely statistically significant 15% drop in ischemic events in a subsample of patients, whereas Esselstyn got a 100% drop in those who stuck to his diet, all the more compelling considering that those 18 participants experienced 49 coronary events, meaning like heart attacks, in the eight years before they went on the diet. And these were the worst of the worst, most of whom having already failed surgical intervention. When the effects are so dramatic how many people do you need?
Before 1885, symptomatic rabies was death sentence until July 6th, when little Joseph Meister became the first to receive Pasteur’s experimental rabies vaccine. The results of this and one other case were so dramatic compared with previous experience that the new treatment was accepted with a sample size of two. So dramatic compared with previous experience, no randomized controlled trial was necessary. Would you—having been infected by a rabid dog—be willing to participate in a randomized controlled trial (RCT) when being in the control group had a certainty of a ‘‘most awful death’’? Sadly, such a question is not entirely rhetorical.
In the 1970s, a revolutionary treatment for babies with immature lungs called ECMO, extracorporeal membranous oxygenation, transformed mortality in these patients from 80% to 20% nearly overnight, from 80% dead to 80% alive. Despite this dramatic success, they felt forced to perform a randomized controlled trial. They didn’t want to. They knew they’d be condemning babies to death. They felt compelled to perform such a trial because their claim that ECMO worked would, they judged, carry little weight amongst their medical colleagues unless supported by a randomized controlled trial.
And so at Harvard’s Children’s Hospital 39 infants were randomized to either get ECMO or conventional medical therapy. They decided to stop the trial after the 4th death so as not to kill too many babies. And that’s what they did. The study was halted after the fourth conventional medical therapy death, at which point nine out of nine of the ECMO babies had survived. Imagine being a parent to one of those four children. Just as one can imagine being the child of a parent who died from conventional medical or surgical therapy for heart disease.
Medical students in the United States are taught little about nutrition. Worse yet, their training actually biases them against the studies that show the power of dietary approaches to managing disease, by encouraging them to ignore any information that does not come from a double-blind, randomized controlled trial. Yet human beings cannot be blinded to a dietary intervention—they tend to notice. As a result, physicians are biased in favor of drug treatments and against dietary interventions for the management of chronic disease.
Evidence is a good thing, especially in medicine. However, the medical profession is focusing too much on one kind of evidence, to the exclusion of all others. Unfortunately, this approach can easily degenerate into ignoring-most-of-the-truly-important-evidence medicine.
And heart disease, is the perfect example. On healthy enough plant based diets, our #1 cause of death may simply cease to exist. The Cornell-Oxford-China Study showed that even small amounts of animal-based food was associated with a small, but measurable increase in risk of some of these chronic diseases. In other words, the causal relationship between dietary patterns and coronary artery disease was already well established before Ornish and Esselstyn undertook their clinical studies. The value of their studies was not so much in providing evidence that such a dietary change would be effective, but in showing that physicians can persuade their patients to make such changes, and also provided interesting data on the speed and magnitude of the change in severe atherosclerotic lesions as a result of dietary therapy. So any complaints that these studies were small or unblinded are simply irrelevant. Because the evidence of the role of diet in causing atherosclerosis is already so overwhelming, assigning a patient to a control group eating the standard American diet could be considered a violation of research ethics.
Evidence of the value of plant-based diets for managing chronic disease has been available in the medical literature for decades. Kempner at Duke John McDougall The Physician’s Committee for Responsible Medicine. Denis Burkitt warned us that the standard Western diet is the standard cause of death and disability in the Western world. Yet physicians, especially in the US, are still busily manning the ambulances at the bottom of the cliff instead of building fences at the top.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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