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Why we need to be aware of the ‘therapeutic illusion’

The illusion of control leads physicians to believe that their efforts and medical tools are more effective than they actually are, writes Dr. David Casarett, a professor of medicine at the University of Pennsylvania.

One of the most stubborn obstacles to reducing unnecessary — and sometimes harmful — medical tests and treatments is a psychological phenomenon known as the “illusion of control,” argues a provocative commentary published Wednesday in the New England Journal of Medicine (NEJM).

In the commentary, Dr. David Casarett, a professor of medicine at the University of Pennsylvania, describes how the illusion of control — which in medicine is sometimes called the “therapeutic illusion” — leads physicians to believe that their efforts and medical tools (tests, drugs, procedures) are more effective than they actually are.

Of course, it’s an illusion that patients have as well, in large part because of the human tendency to confuse correlation and causation.

Chance and bias

 “The outcome of virtually all medical decisions is at least partly outside the physician’s control, and random chance can encourage physicians to embrace mistaken beliefs about causality,” writes Casarett. “For instance, joint lavage [washing cartilage debris out of the joint] is overused for relief of osteoarthritis-related knee pain, despite a recommendation against it from the American Academy of Orthopedic Surgery. Knee pain tends to wax and wane, so many patients report improvement in symptoms after lavage, and it’s natural to conclude that the intervention was effective.”

Another well-known psychological phenomenon — confirmation bias — reinforces therapeutic illusion, he adds. Once a treatment is under way, physicians (and patients) tend to look for evidence that it is having some kind of positive effect. 

“Physicians may be particularly susceptible to that bias when caring for a patient with a complex illness,” Casarett writes. “When a patient has multiple medical problems, it’s often possible to find some evidence of improvement after an intervention, particularly if the patient is being intensively monitored.”

But, again, that improvement may have had nothing to do with the treatment.

Boosting confidence

“The therapeutic illusion is not the only factor driving overtreatment,” Casarett acknowledges. Other influences include “reimbursement pressures, quality measures, fear of litigation, and family expectations,” he says.

There’s also the possibility, says Casarett, that the therapeutic illusion provides benefits for physicians — and for the treatment process.

“Perhaps it contributes to the psychological well-being of physicians and other health care providers by bolstering their confidence and sustaining their belief in the value they offer to patients,” he writes. “It might also be a necessary ingredient in medical decision making. A purely rational approach to decision making in which physicians question and doubt their own effectiveness might lead to undertreatment, with resultant harms that are as substantial as those of overtreatment.”

Still, Casarett says physicians should strive to overcome the therapeutic illusion. He makes several recommendations, including looking for other explanations for why a patient is improving and testing assumptions of a treatment’s success by looking for evidence of its failure.

Choosing wisely

And the rest of us? Casarett doesn’t make any recommendations, but if you want to make more rational, evidence-based decisions about your health care, a good place to start is with the “Choosing Wisely” campaign, an initiative launched several years ago by the American Board of Internal Medicine Foundation and Consumer Reports magazine “to help physicians, patients and other health care stakeholders think and talk about overuse of health care resources in the United States.”

So far, the several dozen medical societies participating in the Choosing Wisely campaign have recommended dozens of tests and treatments that are used inappropriately. You’ll find them listed on the Choosing Wisely website.

You can also read Casarett’s commentary in full on the NEJM website

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Comments (2)

  1. Submitted by Paul Brandon on 03/31/2016 - 09:48 am.

    Thanks again!

    In other words, much of ‘modern’ medicine is a placebo effect; the better controlled the study, the larger the placebo effect.

  2. Submitted by Ray Schoch on 03/31/2016 - 06:59 pm.


    Indeed, while I’ve had major surgery and acute conditions in both childhood and adulthood, I’ve also survived many a minor injury, and dozens of illnesses, without ever seeing a doctor – and I come from a medical professional family. There are plenty of conditions where Hippocrates’ most important rule, “First, do no harm,” really IS the most important thing to keep in mind.

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