Diagnoses: When are several opinions better than one?

July 22, 2016, Max Planck Society
Several doctors often make better diagnoses - provided the individual abilities within the group don't differ too much. Credit: © Fotolia / Syda Productions

Methods of collective intelligence can result in considerably more accurate medical diagnoses, but only under certain conditions. A study headed by researchers at the Max Planck Institute for Human Development has shed new light on how medical diagnostics can be boosted by obtaining several independent judgements. The researchers also found that the group composition is decisive for the quality of the diagnosis.

Four eyes are better than two - this rule has long been valid when it comes to making serious medical diagnoses. But when is it actually better to seek several opinions and how many should be sought? These are the questions that researchers at the Max Planck Institute for Human Development and the Leibniz-Institute of Freshwater Ecology and Inland Fisheries have been looking into.

"We have been investigating how social systems in nature - such as fish swarms - process information and how this can be used to improve human decision-making processes," Max Wolf from the Leibniz Institute of Freshwater Ecology and Inland Fisheries explains the method.

In a follow-up study, the researchers have now examined how the of individual doctors affects the collective diagnostic outcome. "Collective intelligence is a promising approach to making better decisions. We were interested in which conditions have to be met for the group's decision to be better than that of the best individual in the group," says Ralf Kurvers, lead author of the study and researcher in the Center for Adaptive Rationality at the Max Planck Institute for Human Development.

Similar individual abilities within a group are key

The study shows that the diagnostic accuracy of the doctors whose diagnoses are combined has to be similar. Only then can the collective outperform the best individual in the group. If, in contrast, doctors' levels of accuracy differ too much, combining their decisions leads to worse diagnostic outcomes. This effect holds across different group sizes and different performance levels of the best group member. "It is not the case that groups always make the best decisions. If individual abilities differ too much within the group, it makes more sense to rely on the best diagnostician in the group," says Ralf Kurvers.

For their study, the researchers used two large datasets available from previous studies on breast and skin cancer diagnostics. They were thus able to draw on more than 20,000 diagnoses made by more than 140 doctors to determine individual diagnostic accuracy. They used this information to identify the conditions under which diagnoses made using collective intelligence rules are more accurate than the diagnoses of the best individual. Specifically, they applied the choose-the-most-confident rule and the majority rule. The choose-the-most-confident rule adopts the diagnosis of the doctor who has the highest confidence in his/her diagnosis; the majority rule takes the diagnosis given by the most doctors.

"Our findings represent another major step in understanding how collective intelligence emerges," says co-author Max Wolf, who investigates in natural settings at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries. The new findings underline how important the diagnostic accuracy of individual doctors is for the overall outcome. Diagnostic accuracy should therefore be a key criterion for assembling groups in medical diagnostics – for example, in the context of independent double reading of mammograms. In future work, the researchers plan to find out what information is needed to gauge a doctor's diagnostic accuracy as quickly as possible.

Explore further: Collective intelligence helps to improve breast cancer diagnosis

More information: Ralf H. J. M. Kurvers et al. Boosting medical diagnostics by pooling independent judgments, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1601827113

Ralf H. J. M. Kurvers et al. Detection Accuracy of Collective Intelligence Assessments for Skin Cancer Diagnosis, JAMA Dermatology (2015). DOI: 10.1001/jamadermatol.2015.3149

Related Stories

Collective intelligence helps to improve breast cancer diagnosis

August 13, 2015
Breast cancer is the most frequent type of cancer in women and currently accounts for 29% of all new cancer cases in the U.S. Wide-ranging mammography screening programs have been set up for early diagnosis. However, even ...

How doctors make diagnoses

December 14, 2011
Doctors use similar brain mechanisms to make diagnoses and to name objects, according to a study published in the Dec. 14 issue of the online journal PLoS ONE and led by Marcio Melo of the University of Sao Paulo in Brazil.

Study finds that most visits to ER for chest pain are not life-threatening

June 14, 2016
Chest pain is one of the most common reasons to visit the emergency room, but a new UC San Francisco study shows that only a fraction of all cases actually lead to a diagnosis of a life-threatening condition.

Recommended for you

Improving heart health could prevent frailty in old age

May 21, 2018
New research has shown that older people with very low heart disease risks also have very little frailty, raising the possibility that frailty could be prevented.

Exercise to stay young: 4-5 days a week to slow down your heart's aging

May 21, 2018
Participating in exercise 4-5 days per week is necessary to keep your heart young, according to new research published in The Journal of Physiology. These findings could be an important step to develop exercise strategies ...

One in 10 parents say their child has gotten sick from spoiled or contaminated food

May 21, 2018
No parent wants to come home from a picnic or restaurant with a little one whose stomachache turns into much worse.

Little difference between gun owners, non-gun owners on key gun policies

May 17, 2018
A new national public opinion survey from the Johns Hopkins Bloomberg School of Public Health finds widespread agreement among gun owners and non-gun owners in their support for policies that restrict or regulate firearms.

Giving employees 'decoy' sanitizer options could improve hand hygiene

May 17, 2018
Introducing a less convenient option for hand sanitizing may actually boost workers' use of hand sanitizer and increase sanitary conditions in the workplace, according to findings in Psychological Science, a journal of the ...

Research shows that sexual activity and emotional closeness are unrelated to the rate of cognitive decline

May 16, 2018
Older people who enjoy a sexually active and emotionally close relationship with their partner tend to perform better at memory tests than sexually inactive older adults on a short-term basis, but this is not the case over ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.