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Contact: Hal Arkes, 703-306-1757, ext. 6983; harkes@nsf.gov
WASHINGTON, D.C. -- Physicians hired as expert witnesses in medical malpractice lawsuits have an advantage over the physician on trial: When asked how they would have diagnosed a patient's symptoms, they already know the answer.
Responding with confidence that they would have come to the correct medical conclusion in the case before the jury, these witnesses offer convincing testimony for the prosecution. But is it accurate testimony?
"The jury and the expert witnesses are looking back on an event and they know how it turned out. It biases their perception of what should have been done," says Hal Arkes, a professor of psychology at Ohio University who does research on medical decision making and physician overconfidence.
This phenomena, called hindsight bias, can predispose a jury in a medical malpractice suit to a guilty verdict, Arkes says. But perhaps even more troubling, he adds, is the consequences it poses for the education of physicians and medical students.
Teaching hospitals often require physicians and students to participate in clinicopathologic conferences (CPCs) – forums in which one person presents a medical case, offers a diagnosis and awaits the announcement of the actual cause of death, presented later by a pathologist.
"Physicians and students in the audience are supposed to learn things about treating people with the same symptoms," says Arkes. But a study done by Arkes and Case Western Reserve University researcher Neal Dawson and their colleagues showed that these forums are less effective than they might otherwise be due to physician overconfidence attributable to hindsight bias. The study of 160 doctors and medical students at a Cleveland hospital was presented Feb. 21 at the American Association for the Advancement of Science meeting in Washington, D.C.
For the study, Arkes and Dawson asked half the participants to complete a questionnaire after the case was presented but before the cause of death was revealed. Called the foresight group, these people were given a list of five possible diagnoses and asked to assign a probability that each was the correct answer.
The other half, called the hindsight group, was asked to fill out the same questionnaire after the pathologist revealed the actual diagnosis, listing the probability they would have assigned to each item had they not known the correct answer.
The results? People in the foresight group were less likely to select the correct diagnosis, acknowledging that the cases presented were difficult and wouldn't have been easy to diagnose. But members of the hindsight group, aided by the knowledge of the actual diagnosis, were more likely to choose correctly.
"Rather than learning as much as they could, the physicians in the hindsight group felt they knew the right answer all along," Arkes says. "They lost a wonderful educational opportunity."
In the hindsight section, the only group that claimed they wouldn't have known the right answer were those physicians with more years experience in the field, Arkes says, which the suggests younger, more inexperienced physicians – the ones who need the educational training the most – are more likely to be overconfident.
"In hindsight, we underestimate how difficult the task was in foresight," he says. "It's unfair to in hindsight to evaluate people who only had a foresight perspective."
Teaching hospitals could eliminate hindsight bias simply by having physicians and students list probable diagnoses before the actual diagnosis is offered. In tougher cases, more people might choose the wrong answer, Arkes says, but those cases help them make a better diagnosis later for their patients.
Removing hindsight bias from the courtroom is a more difficult task, he says, but one the courts should attempt if a fair verdict is the desired outcome.
"It's important to try to get people to say what they would have done without knowing how it turned out."
Neal Dawson, professor of medicine and associate professor of epidemiology and biostatistics at Case Western, was co-author of the study. Arkes holds an appointment in the College of Arts and Sciences.
Written by Kelli Whitlock.