Clinicians often misestimate interventions’ harms, benefits

Kevin B. O'Reilly
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AMA Wire
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Physicians and other health professionals frequently overestimate and underestimate the harms and benefits of medical treatments, screenings and tests, according to a recently published systematic review of medical literature on the subject. Decision-support tools can help address knowledge gaps and inform patient-physician discussions.

Researchers did a comprehensive search of four medical databases and found 48 articles published between 1981 and 2015 examining 13,011 clinicians’ knowledge of harms and benefits. Nine of the articles surveyed physicians along with other health professionals, such as physician assistants or nurses. The vast majority of the 48 studies, however, focused solely on physicians’ knowledge in areas such as medication, imaging, cancer screening, fetal and maternal medicine, and cardiovascular disease prevention and management.

In the studies that examined how often clinicians correctly estimated interventions’ benefits, a majority of respondents provided the right answer for just three in 28 interventions. Of the studies that examined harm expectations, most of the clinicians provided the correct estimate for only nine out of 69 interventions.

When it came to underestimating the harm of tests, screenings or treatments, a majority did so for 20 out of 58 interventions. For example, more than 90 percent of respondents underestimated the fatal cancer risk from a bone scan. Most clinicians overestimated benefits for seven out of 22 interventions examined. As a case in point, greater than 60 percent of clinicians overestimated how much antibiotics could help relieve the pain of tonsillitis.

A majority of clinicians underestimated benefits 9 percent of the time, while they overestimated harm 5 percent of the time, said the study, published online Jan. 9 in JAMA Internal Medicine and co-authored by a team from the Bond University Faculty of Health Sciences in Queensland, Australia. The systematic review did not examine how clinicians’ incorrect estimates of harms and benefits affected patient care.

    The authors argue that the tendency of physicians and other health professionals to overestimate benefits and underestimate harms offers support for the notion of “therapeutic illusion,” which is when patients and physicians have unjustified enthusiasm for treatment, screening or testing. “Clinicians may seek evidence that supports interventions they believe to be effective and already use in a possible illustration of confirmation bias,” they wrote.

    According to the authors, other factors potentially contributing to the problem are:

    • A preoccupation with pathophysiological mechanisms of interventions rather than trial-derived effectiveness
    • The difficulty of keeping up to date with the evidence for interventions, which is compounded by the exponential growth in trials and systematic reviews
    • The dynamic nature of evidence for many interventions
    • The difficulty of extrapolating accurately from trial evidence to individual patients
    • The inherent uncertainty that accompanies benefit and harm estimates

    “Solutions for redress are not easy,” they added. “Shared decision-making is a logical mechanism for bringing evidence into consultations, but this requires clinicians to know the best current evidence about the benefits and harms of the interventions being contemplated. To facilitate discussions, clinicians need ready access to up-to-date, concise and clear summaries of intervention benefits and harms.”

    Decision-support tools can help. In particular, the authors—Chris Del Mar, MD, and Tammy C. Hoffman, PhD, of the Centre for Research in Evidence-Based Practice—highlighted the Sharing Evidence to Inform Treatment Decisions (SHARE-IT) tool made available by the MAGIC project. This tool can be used to create decision aids generated from evidence summaries in guidelines or systematic reviews.

    AMA members can receive a free 18-month trial of DynaMed Plus, an evidence-based, physician-developed reference tool to help physicians get immediate answers to clinical questions in many specialties.

    The AMA’s STEPS Forward™ collection of practice-improvement modules offers concrete advice on how to use clinical decision support as part of the image-ordering process and how to incorporate the Choosing Wisely® recommendations into your practice. These modules may also be completed for continuing medical education credit. There are seven new modules now available from the AMA’s STEPS Forward collection, bringing the total number of practice improvement strategies to 43; several thanks to a grant from, and collaboration with, the Transforming Clinical Practices Initiative.

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