For practical and theoretical reasons, says Michel Accad, evidence based medicine is flawed and leads to standardised rather than excellent individualised care, but
Darrel Francis argues that it protects patients from seemingly rational actions that cause more harm than good.
This is an interesting conflict arising when EBM, which is population-based, runs into individualized medicine, which is mostly based on a doctor’s judgment.
Consider Dr Smith, a conscientious physician who keeps abreast of the medical literature and is attentive to the individual needs of her patients. Smith is well respected by her colleagues for the wisdom of her decisions.
For example, when she sees a patient with chest pain that is unlikely to be ischaemic, Smith rarely orders a stress test. She knows that the risk of a false positive result outweighs the possibility of diagnosing coronary disease.
She believes that, under certain circumstances, after considering all alternative courses of action, it may turn out to be in a patient’s best interest to disregard the objective evidence on stress tests. Can Smith be said to practise evidence based medicine (EBM)?
At first glance, proponents of EBM seem willing to answer in the affirmative and grant Smith her decisional prerogative. For example, a well established definition of the EBM is “the conscientious, explicit, and judicious use of best evidence in making decisions about the care of individual patients.”
Judicious use of best evidence implies that evidence is subject to judgment.
But this lenient interpretation runs the risk of trivialising EBM. After all, what’s the point of calling attention to the importance of the evidence if that evidence can be discarded willy-nilly by the clinical judgment of the doctor? Isn’t EBM meant as a safeguard against the reasoning errors of physicians?
To defend the importance of EBM, its architects feel compelled to backpedal. They specify that “good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough.”
Evidence, then, is a check against clinical judgment gone awry.
How can evidence be a check on judgment when judgment is obviously required to appraise the quality of the evidence and its relevance to the patient at hand?
What’s amiss is that EBM’s professed respect for clinical judgment is, at best, only wishful or, at worst, simply disingenuous.
A clue to that effect is provided by US EBM guru David Eddy, originator of the term “evidence based,” who recently remarked that the evidence based movement arose primarily from a desire to standardise care, not to individualise it
This is the ultimate truth and ultimate goal, no matter how much proponents of EBM dance around it.
EBM = standardization
This is medically inappropriate because it wrongly assumes that population health = individual health.
Eddy’s point is obvious when we consider the institutions and organisations that have enthusiastically embraced EBM from the start: national health systems, private healthcare payers, regulators, drug companies, public health departments, and disease specific interest groups have all taken a keen interest in EBM precisely for its ability to formulate standards of care—that is, clinical guidelines—and to encourage, reward,3 or even oblige45 doctors to practise in accordance with those standards.
But practising according to standards is antithetical to practising according to clinical judgment: standardisation can only identify best practices for an “average patient” under average conditions.
Clinical judgment is personal and seeks to decide what is best for this specific patient at this specific time.
Standardisation aims to improve outcomes;
clinical judgment aims to improve health.
The two goals are clearly distinct.
EBM may allege to reduce cognitive bias, but it introduces a bias of its own: the tendency to treat according to population norms rather than personal needs, a “groupthink” of sorts.
Standardisation informed by EBM, then, will necessarily deny Dr Smith the freedom to care for her patient on the basis of her judgment. It is no longer judgment that rules but evidence that decides.
EBM’s adverse influence on clinical judgment is not unexpected. Early critics of EBM pointed out its internal contradictions:
- individual decision making cannot be based on general evidence, and
- clinical judgment cannot be specified by methodological formalities
EBM contains within itself the seeds of its own demise. The confused premises on which it is based can only confuse the clinical judgment that it claims to assist.
No— Darrel Francis
Imagine an electrician comes to your house to repair a washing machine that repeatedly breaks down. She adjusts a screw deep inside the machine.
How would you feel to learn that this adjustment had never been found to reduce recurrence of breakdowns? And that it had multiple consequences whose net effect was unknown?
Evidence based medicine expects doctors to choose among tweaks that have been found to do more good than harm; not just among tweaks that they or their institution like to do for financial reasons or to feel good about themselves.
Draw of autonomy
Inevitably we doctors dislike the straitjacket of EBM restricting our freedom to treat patients with water (because we like the sound of homeopathy) or diagnose their diseases by feeling the bumps on their head (because we read about it in a magazine).
It is annoying to be limited to things that somewhere, somehow, someday, genuinely worked.
But this would prevent doctors from “trying” treatments that may be appropriate for this individual patient versus forcing them to endure treatments that have been ruled to be “evidence-based” but may be totally ineffective for them.
Example: NSAIDs for pain control should not be given to patients with pre-existing heartburn or ulcers.
We are all trapped in our bubble of beliefs.
My belief is that EBM should be used as one input to a doctor’s decision, which should be based on a doctor’s judgment and weighing of alternatives.
Consensus of beliefs does not automatically make them correct.
…like the decision made that EBM should rule, or the belief that “opioids don’t work for chronic pain”.
EBM protects our patients not from nonsensical therapies but from rational ones that cause more harm than good. The human body is incomprehensibly complex.
We consistently overestimate our ability to understand biology well enough to personalise tests and treatments beneficially. Personalisation may be harmless fun and even increase the placebo effect, but we should be under no illusion that we have done anything useful.
My favourite example of the need for EBM, even for astute clinical scientists, was inadvertently provided by a friend, a veteran of many guideline writing committees, who said:
“We are not treating many HF [heart failure] patients who would benefit from CRT [cardiac resynchronisation therapy] simply because there are no scientifically evidence-based guidelines telling us to.
These days, guidelines are often not scientific, but rather politically expedient.
I have used CRT successfully in patients with narrow QRS [complex], and so have many others. The medical literature supporting this belief is increasing with observational studies and anecdotal cases of success in several thousands of these patients.”
My views on this are very likely due to the fact that I am so decidedly NOT “average”: I have a rare genetic syndrome and this means that none of the EBM approaches to my symptoms were helpful (and some were damaging, like yoga).
Only when doctors realized that there was something different and unusual going on with me and dropped their reliance on EBM did we make any progress.
He went on to lead a randomised trial. Unfortunately, the large effect found was an 80% increase in mortality.
Again, the RCT showed population-based benefits/costs. To me, it seems highly likely that individual doctors were able to figure out (screen) which patients would benefit from this procedure and thus achieve high rates of success, while RCTs applied it “randomly” to patients who did or did not benefit.
It’s the doctor’s judgement that makes a difference that a computer algorithm cannot reproduce.
I absolutely agree. There’s no substitute for human judgment, no matter how technologically advanced medicine becomes.
Humans are capable of “intuitive leaps” that no computer can emulate.