Mon 21 Oct 19
People overestimate health-related risks, and make different decisions, depending on how doctors chose to explain the likelihood of something happening, University of Essex researchers have found.
Previous research by the same researchers has shown that people overestimate the risk of something happening when it is given in a “1 in x” ratio – e.g. 1 in 10 chance of contracting malaria – compared with a different format such as a “N in N*x” ratio – e.g. 10 in 100 chance of contracting malaria.
The researchers - Dr Miroslav Sirota and Dr Marie Juanchich, from the Department of Psychology - also found that the “1 in x” ratio remains a popular method used by health professionals to communicate the risk of something to their patients.
Now, a new Essex study into risk-related communication, led by Dr Sirota, has shown that people make a different decision when they are given the risk of something happening in a “1 in x” ratio compared with those given the risk in a “N in N*x” ratio.
For example, in their study, participants reported they would take recommended steroids less when the chance of a side effect changing their mental state was described as 1 in 20 compared with those participants who were told the chance was 5 in 100.
“We want people to make the right, informed decisions based on the information they receive, especially when it comes to health-related risks,” explained Dr Sirota. “But the reality is they might make their decision based on misinterpreting the probability of a risk.
“It is about giving the information in the appropriate format as we want people to understand what they are told based on the facts, rather than on the way the information is being communicated.”
Dr Sirota said there was an easy solution with health professionals making a very simple change to the way they communicate risk to patients.
“Using a ‘1 in x’ ratio to explain medical risk might appear to be a really helpful and easy-to-understand way of communicating with patients, but our research has found that people often overestimate such risk. If we are to have accurate risk perceptions there are better formats than ‘1 in x’ ratio to communicate risk,” he added.
The studies looked at how people responded to the same probability of risk when said in several different ways - e.g. 1 in 20 and 5 in 100. Researchers found that people would make 12 additional suboptimal decisions out of each 100 decisions if they received the risk communicated in “1-in-x” ratio compared with the “N-in-x*N” ratio. The result was the same irrespective of the person’s age, gender and level of education.
“We don’t know exactly why this is,” added Dr Sirota. “It might something to do with how easy it is to think about ratios starting with 1 or with how it is often associated with severe outcomes, understanding the mechanism behind this would be an interesting next step for the research.”