Evidence-Based Medicine: What's the Evidence?

My charge is to debate against evidence-based medicine; yet, I am not opposed to evidence. Clearly, the more evidence we accumulate the closer we get to understanding an issue. Researchers and clinicians alike must therefore forge forward in the rigorous pursuit of knowledge. However, we must use the restraint, precision, and caution of a microsurgeon when we discuss evidence, truth, and knowledge. We must dissect these words, separating them into their rightful places, lest we adulterate their meaning and reduce them to twisted unrecognizable constructs. The reason is that these words are not equivalent. Evidence is information that is used to approach truth, whereas truth is infallible, unequivocal, immutable fact. The definition of knowledge has been debated through the ages, but the term is typically used as a representation of a person’s comprehension of a particular subject. We see, therefore, that although truth is the object of our desire, being absolute, it is likely unattainable. Evidence does imbue us with knowledge, but in no way does it affirm truth. Thus, evidence-based medicine cannot be our conduit to truth. It is, however, a system that can, when used correctly, enhance our ability to care for patients. Strictly speaking, evidence-based medicine seeks to use the best signals garnered from the best science to make clinical decisions. A hierarchy of medical evidence has been constructed with double-blind, placebo-controlled, randomized clinical trials (RCTs) on top, and experiencebased clinical acumen on the bottom. The justification of this hierarchy has been called into question. Although its roots dive to the depths of statistics, even the brightest of the statisticians have raised eyebrows about our current construct. In addition to statistics, the issue spans science, philosophy, and mathematics. To elucidate the shortfall and even danger of today’s love affair with evidence-based medicine, I examine our methods for acquiring knowledge and demonstrate not only why our current system fails to meet its goals, but also how its failure spawns often unrecognized yet decidedly dangerous consequences. Deductive and inductive reasoning represent the 2 distinct but often interconnected approaches we use to acquire knowledge in the pursuit of truth. Deductive reasoning moves from the general to the specific, a classic example being, ‘‘All men are mortal. Socrates is a man. Therefore Socrates is mortal.’’ Inductive reasoning moves in the opposite direction, taking a specific observation and using it to draw a general inference. An example of inductive reasoning can be seen in our RCTs: in a small group of prespecified study patients, drug x decreases cholesterol and consequently decreases heart attacks by 30%. Giving drug x to all patients with characteristics similar to those in the study group will therefore reduce their risk of heart attacks by 30%. Although deductive reasoning does not depend on our observations and perceptions, inductive reasoning does. Plato—and many other philosophers and scientists—maintained that the human flaw inherent in inductive reasoning makes it an inferior means to approach the truth. Plato’s cave allegory depicts this nicely. In the cave, man observes shadows and based on his particular perspective infers their meaning. The shadows are, of course, reflections of something, not the thing itself. Our current gold standard for science, the RCT, uses inductive reasoning to draw conclusions. Making matters worse, RCTs’ conclusions are by definition simply expressions of probability; they are decidedly not the truth. The evidence accumulated through these trials, although purely proxies for truth, have been crowned as truth. By doing this we have allowed and even fostered the illusion that the best of our clinical trials answer questions of truth and falsehood. They do not. In fact, they were not originally intended to illuminate truth; they were only meant to bring us closer to it. By distorting the factual significance of the outcomes of these trials, we put our faith in the shadows of Plato’s cave, bowing to them as though they were divine. Allowing ourselves (and the public) to be misled into believing we know what we in fact do not, we not only draw erroneous scientific conclusions, but also carelessly discard sound, benchtop science in addition to well-earned clinical acumen. Instead, we adopt phantoms of truth. We pray to idols. We have become prisoners of our own design, handcuffed by our self-imposed methodologies. So then how accurate are our top-notch RCTs? In their 2011 article, ‘‘The Frequency of Medical Reversal,’’ Dr. Prasad et al. succinctly demonstrated the alarmingly high frequency of medical reversals.1 To localize the rate of reversal, they searched 1 year in the New England Journal of Medicine for original papers. They found that of the original papers making claims about medical practice, 13% represented true reversals. They defined reversal as, ‘‘a new trial—superior to predecessors because of better design, increased power or more appropriate controls—contradicting current clinical practice.’’ Thus, reversals are not only commonplace, but they have far-reaching implications, often unwinding and dismantling clinical practices that frequently include surgery, medications, or a combination of both. These practices typically have had great impact on the lives of many, meaning that reversals are often accompanied by patient and physician angst, anger,