Nocebo and informed consent: words matter

“Sticks and stones may break my bones, but words will never hurt me.”

I THINK we all sensed, when our parents told us to chant this in response to bullies, that we were being sold a crock.

Words have power, and every child knows it.

That may be as true in the clinical setting as it is in the playground.

The words a clinician chooses to use with a patient have the potential to improve outcomes, or increase the severity of symptoms and side effects. Effects of the use of words have been found in studies of b-blockers, statins, oral contraceptives and epidural anaesthesia, among others.

Words can heal, but they can also trigger a powerful nocebo effect. Nocebo is the placebo effect’s evil twin: just as an expectation of benefit can be self-fulfilling, so can an expectation of harm. Multiple studies show that patients who are warned about the potential side effects of a treatment are much more likely to experience them.

Warnings can trigger symptoms even in patients enrolled in the placebo arm of a trial, as a 2012 review showed, revealing reported effects as varied as wheezing, headache, sleep problems, back pain, nausea, constipation, itching and vision problems.

“Some of the information that physicians convey to their patients can inadvertently amplify patients’ symptoms and become a source of heightened somatic distress, an effect that must be understood by physicians to ensure optimal management of patient care,” writes US psychiatrist Dr Arthur Barsky in JAMA.

“This effect illustrates the iatrogenic [harm caused by medical treatment] potential of information, as opposed to the iatrogenic potential of drugs and procedures.”

Pain appears to be particularly sensitive to both placebo and nocebo effects, and both can be triggered by language as well as by sugar pills.

In a study of epidural anaesthesia during childbirth, for example, women who were told that the injection of the local anaesthetic would feel like “a big bee sting; this is the worst part” reported significantly more pain than those told that it “would numb the area and you will be comfortable during the procedure”.

For a different kind of pain, a study of b-blocker treatment for hypertension found that 32% of patients who were explicitly warned that erectile dysfunction was a possible side effect experienced the problem, compared with only 13% of those who were not warned.

From the clinician’s perspective, all this might seem like a case of “damned if you do, damned if you don’t”.

Informed consent requires patients to be told about risks of treatment. Telling patients about possible effects makes it more likely they’ll experience them. What to do?

Dr Barsky argues that there could be a middle way.

“When obtaining informed consent, physicians must absolutely provide complete and truthful information and must avoid fostering a ‘paternalistic’ patient–physician relationship,” he writes.

“But balancing the requirement for full and complete disclosure with the iatrogenic potential of some information is problematic.”

The solution might lie in tweaking the approach to informed consent, he suggests.

“When prescribing a medication, all serious and medically significant adverse effects are of course described, and the patient is instructed to report all adverse effects; however, if the patient agrees, benign, non-specific symptoms are not enumerated in advance because it is explained that doing so makes them more likely.”

Essentially, the patient is being asked to consent to not being informed.

Many doctors probably already have strategies to reduce the potential impact of warnings about side effects, whether or not they would describe them as iatrogenic.

But reconciling the principle of informed consent with the desire to protect a patient from information that could harm them is always going to be a tricky balancing act.

Jane McCredie is a science and health writer based in Sydney.

 

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