Patients overestimate benefits, underestimate harms of medical testing

Patients tend to overestimate the benefits from medical tests and treatments such as mammography or PSA testing, and underestimate the harms, according to an article in the February issue of JAMA Internal Medicine. 

Tammy Hoffmann, PhD, and Chris Del Mar, MD, both of Bond University in Brisbane, Australia, carried out of a review of 35 studies analyzing patient expectations of certain medical interventions. Fourteen of the studies involved screening, 15 involved treatment, three testing, and three both treatment and screening.

Of the 35 studies, 32 looked at expectations of benefit and 21 compared the participants’ responses with the study authors’ estimates of benefit. The majority of participants overestimated the benefit for 22 (65%) of the 34 outcomes for which overestimation data were provided. The proportion of participants who overestimated benefit ranged from 7% to 94%.

Eleven studies included comparisons of harm with the study authors’ estimations. Hoffman and Del Mar found that at least 50% of participants underestimated the harm for 10 of the 15 outcomes for which underestimation data were available.

Why does this matter?

According to a post Hoffman and Del Mar wrote for the University of Queensland website, “overly optimistic expectations undoubtedly contribute to the ever increasing use of health services and the growing problem of over-diagnosis, where disease labels are given even though the latent disease might not have ever caused symptoms, and over-treatment, where unnecessary treatments given.”

They went on to point out that many payment systems encourage medical interventions rather than having healthcare providers take the time to explain to patients why a particular test may not be needed.

“In the process of negotiating the best clinical option, clinicians should elicit the patient’s expectations and preconceptions about what they are expecting from the intervention, discuss any misperceptions, and provide accurate information about the benefits and harms of each management option,” they wrote. “Only then can any genuine “shared decision making” start to occur and perhaps the impact of these great expectations lessened.

In an invited commentary Deborah Korenstein, MD,  of the American College of Physicians, wrote that while the study’s finding “may not be surprising and likely reflects a number of underlying issues . . . the systematic tendency for patients to misunderstand benefits and harms is a fundamental threat to our ability to improve health care value and must be addressed.”