by Ryan Ozawa
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What is evidence-based medicine?
by Ryan Ozawa
The COVID-19 pandemic has pushed health care to the forefront of public attention and interest. And thanks to the global race to find a vaccine, people are focused on the science of medicine as well.
One term you’re likely to encounter is “evidence-based medicine,” or “evidence-based care.” A universally accepted definition is hard to come by, but many experts cite A.L. Cochrane in his seminal work, Effectiveness & Efficiency, from 1972. He wrote:
Evidence-based health care is the conscientious use of current best evidence in making decisions about the care of individual patients or the delivery of health services. Current best evidence is up-to-date information from relevant, valid research about the effects of different forms of health care, the potential for harm from exposure to particular agents, the accuracy of diagnostic tests, and the predictive power of prognostic factor.
Put more simply, Brian Haynes of McMaster University describes evidence-based health care as “the transfer of research results into practice.”
Isn’t all medicine evidence-based?
With the singular goal of improving patient outcomes or the health of a population, it makes sense that health care providers would turn to the most advanced medical research to determine the best course of action. In this sense, evidence-based medicine is a fundamental part of public health.
However, the term includes more than just medical research findings or the consensus of a whole field of medical practitioners.
The three main goals of health care, according to the Institute for Healthcare Improvement, are improved quality, improved patient satisfaction, and reduced costs.
Similarly, the three components of evidence-based medicine can be described as:
- Research-based evidence
- Clinical expertise (i.e., the clinician’s accumulated experience, knowledge, and clinical skills)
- The patient’s values and preferences
Using the results of research to design treatment plans is only part of the equation. The results of a practitioner’s own experiences also come in to play.
And perhaps most often overlooked is the need for a dialogue between a patient and their health care provider, in which the patient plays a part in decision making based on their own preferences and values. This is known as patient activation.
What kinds of evidence are taken into account?
Again, the results of medical research are only part of the picture. But they are an important part. How do you weigh the value of other types of evidence?
Many health care professionals use a model developed by Canadian physician David Sackett, who wrote a book called Evidence-Based Medicine: How to Practice and Teach EBM which is known as “the bible of evidence-based medicine.”
Sackett proposes using a pyramid of evidence, with the strongest type at the top:
- Level 1: Evidence from one or more randomized controlled trials (RCTs)
- Level 2: Evidence from: (a.) controlled trials without randomization, (b.) evidence from cohort or case-control analytics studies; or (c.) evidence from multiple time series (observational) studies
- Level 3: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees
- Level 4: Evidence based on personal experience or anecdotes
Why wouldn’t you adopt evidence-based medicine?
Evidence-based care is a broadly agreed-upon objective, but it is not universally practiced. Usually, this is a result of factors beyond the health care setting.
Long-standing cultural or even medical traditions can sometimes inhibit the advancement of evidence-based medicine.
For example, for decades, stroke patients were widely treated with calcium channel blockers. It took a comprehensive review of all available research in 1999 to determine that the treatment showed no evidence of a beneficial effect.
Politics can play a part as well. In an interview with the World Health Organization (WHO), leading Africa health researcher Charles Shey Wiysonge noted that evidence may lead to conclusions that run counter to what a government believes.
“Sometimes, policy-makers ignore the evidence because it’s not what they want to hear,” Wiysonge said. “There are many examples of unspeakable and unnecessary suffering resulting from the failure to take an evidence-based approach.”
Although the definition of evidence-based medicine may vary, it generally calls for following the latest and most complete medical research as a means to recommend and improve patient care. It should include the input of the patient, and it’s important to avoid practices based solely on tradition or subjective personal experience.