Patients Clueless About Treatment Risks
Thursday, February 12, 2015 12:14 PM

Patients are dangerously clueless about the true value of many common medical interventions, and physicians aren't doing enough to correct their misunderstandings.  That's according to a first-of-its kind meta-analysis of 36 studies, which ran in JAMA Internal Medicine.

"What surprised us was the consistency of the finding," says lead author. "Regardless of what treatment, test, or screening effort, or what country the study was done in, patients greatly overestimated benefits and greatly underestimated harms."

Chalk it up in part to physicians' true desire to "try something" for their patients, their limited exposure to shared decision-making, poor explanatory skills, or their simple desire to submit a claim. Misleading advertising from pharmaceutical companies' and nonprofit advocacy groups' exaggerated campaign claims share some of the blame, she adds.

Researchers collected papers that asked a total of 27,323 patients about their perceived benefits and/or their perceived harms from getting mammograms, prostate-specific antigen (PSA) and pap smear tests, mastectomies, and CT scans, to name a few.  The articles then compared what patients thought the interventions would accomplish, with actual, known rates of benefits and harms.

They were wrong most of the time.  For example, on almost every study in which women were asked about mammography, they greatly overestimated its ability to either find a true cancer or prevent death. Men were greatly uninformed about the accuracy, benefits, and harms of PSA screening.

"It's a huge problem with no easy answers. Patients are largely at the mercy of what the physician knows, and the onus is on him or her to be up to date. Some are, but others are not so skilled at keeping up."

Authors attribute much of the problem to physicians' rusty math skills or what she calls "poor numeracy.” "I've spent much of my career teaching doctors how to understand evidence, which they really don't understand that well.  So they end up having a very hard time explaining it to patients. For example, doctors and the public have a hard time understanding the difference between a therapy's relative benefit or harm with its absolute benefit or harm.

Here's an example: "It sounds much nicer and cleaner to say to a patient, 'this is going to reduce your chance of having a heart attack by 30%.' But if the doctor says it another way, 'this intervention is going to reduce your chance of a heart attack from .1% to .07,' that's more accurate, but it doesn't sound so attractive."

Likewise for the controversial mammography screening initiatives in the U.S. and in Europe. Numerous studies have found that large numbers of women believe mammography saves countless lives from breast cancer. In fact, studies of half a million women show the absolute risk reduction to be one woman's life saved for every 2,000 women who received recommended screening.

Direct-to-consumer advertising, especially in the U.S., is a problem as well the researchers say, because messages are geared to imply more benefit than can be reasonably achieved.  "This isn't an easy problem to fix, because people just assume that stuff works.”  Sometimes doctors know better, but patients come in with a preconceived notion: They're set on getting a procedure or drug and they don't want to accept "no.” Overutilization is more a function of "poor judgment, subconscious biases, and the pressure in our society to always be doing more. That’s what's driving this stuff,” the authors reported.