What Evidence Based Medicine is Not: Part 1
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Deciding what something is not is just as important as knowing what something is. This is why we use pertinent negatives in clinical practice because they help us make deductive clinical decisions. They eliminate what is not to know what is. For example, when we have a patient with a red eye and eye pain the absence of cells and flare in the anterior chamber helps us rule out anterior uveitis. Now we can more appropriately understand what the diagnosis is by eliminating what it is not.
Pertinent negatives can also be applied to difficult and often misunderstood concepts. For example, when we are learning a new concept like evidence-based medicine (EBM) it is not only important to know what it is but also what it is not. As we’ve previously defined in this column, EBM is defined as “the conscientious, explicit and judicious use of current best evidence, combined with individual clinical expertise and patient preferences and values, in making decisions about the care of individual patients.”1 The definition seems helpful enough, right? But, wow, is it poorly misunderstood.
EBM Misunderstood
How so? Before I answer I would argue that most detractors of EBM are refuting a “straw man” version of EBM. In other words, many objections to EBM are toward a misunderstanding of EBM rather than toward the correct depiction of EBM.
Let me explain. The most common misunderstanding I read and hear from peers is the idea that EBM cares only about the randomized controlled trial (RCT). I will call this the “RCT or bust” fallacy. When EBM is presented or interpreted as “RCT or bust” the response is usually predictable. In fact, I’ve observed two distinct and opposite responses to the “RCT or bust” fallacy. For fun, I’m going to categorize these opposites as “The Snooty Academic” vs. “The Blue-Collar Clinician.”
The Snooty Academic
The Snooty Academic interprets EBM as “RCT or bust” and responds by believing there is no truth to be found except from an RCT. “Is that anecdotal evidence you are quoting from a case study? Silly simpleton,” they say, “show me a double-blind placebo controlled randomized trial and maybe I will believe it.” Obviously, I’m being facetious here, but you get the point. This side accepts “RCT or bust” and responds by avoiding and ignoring all other forms of potential evidence. I can poke fun at them because I’m often one of them. I am naturally cynical of any new treatment and often cringe when I hear other colleagues touting some new treatment as a “game changer” based on their experiences and the probable mechanism of action parroted from company advertisements. Further, The Snooty Academic often refrain from prescribing anything that lacks FDA approval or robust research evidence. Any treatment of lesser quality of evidence is off limits. In essence, The Snooty Academic interprets EBM as “RCT or bust” and loves EBM for it.
The Blue-Collar Clinician
The Blue-Collar Clinician is the antithesis to The Snooty Academic. They interpret EBM as “RCT or bust” and respond by never reading or adhering to a single RCT in their careers because RCTs show “no real-world evidence.” The Blue-Collar Clinician rejects any result from an RCT that contradicts their clinical experience and expertise. They tend to be the everyday in-the-trenches clinicians that rely solely on their hunches and case-by-case experiences. They incorrectly assume that since EBM is RCT or bust, then they cannot accept EBM at all. Instead, they trust their own experiences, their colleagues’ experiences, and their patients’ perceptions above all else. In essence, The Blue-Collar Clinician interprets EBM as “RCT or bust” and hates EBM for it.
So toward which side do you lean?
To help you, I’ve created a quick assessment to help you uncover your type. Ask yourself this question: how did I respond to the results of the DREAM (The Dry Eye Assessment and Management Research Group) study on omega-3 fatty acids? Did you scoff? Or did you swear off all recommendations of omega-3s?
For a brief review, the DREAM trial randomized patients with moderate to severe dry eye to receive either 3000mg of omega-3s or olive oil placebo. The study concluded that patients with dry eye disease who were taking omega-3s after 12 months “did not have significantly better outcomes than those who were assigned to placebo.”2 The scoffer (The Blue-Collar Clinician) would say, “clearly the study is wrong because I recommend omega-3s and it works for all my dry eye patients.” The Snooty Academic would likely say, “I told you there was no evidence for omega-3s!”, and never prescribe them again due to the lack of evidence.
The Wise Practitioner
If EBM is not “RCT or bust” then what is it? Again, EBM is the process of deriving evidence from the best research, clinical experiences and expertise, and patient preferences to make a clinical recommendation. It is applying RCTs when appropriate but also knowing when they are flawed, unavailable, and therefore do not apply. If so, then clinical experiences, expertise, and patient preferences must be used to make the best decision and recommendation for your patient. Conversely, if a well-designed RCT reveals evidence that contradicts what you believe, you must humbly accept you may be wrong (see future columns on regression to the mean, inevitable bias in observational research, and cognitive bias in decision making). Surprisingly, these scenarios are both encompassed under evidence-based medicine.
This more inclusive understanding of EBM, a more nuanced view lying somewhere in the middle of The Snooty Academic and The Blue-Collar Clinician, is what I call The Wise Practitioner. The Wise Practitioner applies EBM to clinical practice in a way that is both academic and clinically minded. How so? For that you will have to wait until next time when we dive into the mindset of The Wise Practitioner in Part 2 of “What EBM is Not.”
REFERENCES
- Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn’t. BMJ. 1996; 312:71–72.
- Asbell PA, Maguire MG, Pistilli M, Ying GS, Szczotka-Flynn LB, Hardten DR, et al. Dry Eye Assessment and Management Study Research Group. n-3 fatty acid supplementation for treatment of dry eye disease. N Engl J Med 2018;378:1681–90
Dr. Klute owns and practices at Good Life Eyecare, a multi-location practice in Eastern Nebraska and Western Iowa. He is a fellow of the American Academy of Optometry and is certified by the American Board of Certification in Medical Optometry. He writes and lectures on primary eye care practice management, evidence-based medicine, glaucoma, and dry eye disease.
