(Reuters Health) - Patients often misunderstand their own odds of experiencing heart disease and its potential consequences, and that means doctors may need to rethink how they explain risk, a new study suggests.

Researchers found that patients were more worried about heart disease and more willing to take preventive medications when told about their long-term, rather than short-term, chances of having problems like heart attack or stroke.

That’s most likely because the long-term risk generally is a larger numeral, the study team writes in JAMA Cardiology.

So, for example, when a patient is told she has a 50 percent risk of developing heart disease over the rest of her lifetime, she may be more concerned than if she’s told she’s got a 4 percent risk of dying from a heart attack in the next 10 years, even though both may be true.

Patients also took risk more seriously when conveyed in simple numbers or a bar graph, the researchers found.

“It matters how you show people what their risk is,” said lead author Dr. Anne Marie Navar of the Duke Clinical Research Institute at Duke University Medical Center in Durham, North Carolina. “Even the (graphical) tool you use can affect how high they see their risk to be. Certain tools might end up downplaying the severity of the risk. So, if you’re using a happy face diagram where a 15 percent risk is shown as 85 happy faces and 15 frowny faces, patients may see that as a lower risk than if you used a bar graph or just said the number.”

To take a closer look at how the method doctors use to communicate risk might interfere with understanding, Navar and her colleagues recruited 2,708 patients who had joined a registry of patients and providers across 140 U.S. cardiology, endocrinology and primary care practices.

First the patients were all told to imagine that their doctor had told them that they had a 15 percent risk of having a heart attack or stroke in the next 10 years. They were then asked to rate the severity of their risk using a sliding scale (very low, low, medium, high, very high) and to indicate their willingness to take a medication, such as a statin or a blood pressure drug, that would reduce their risk by approximately one-third (very unwilling, slightly unwilling, possibly, somewhat willing, or very willing).

The same procedure was followed with the patients imagining they had a 4 percent risk of death in the next 10 years, and then that they had a 50 percent lifetime risk of having a stroke or heart attack. Unknown to the study volunteers, those risk estimates all described the same hypothetical patient: a person with a 4 percent risk of a heart disease death in 10 years, a 15 percent risk of having a heart attack or stroke in 10 years and a 50 percent lifetime risk of having a stroke or heart attack.

Although the numbers were all reflections of the same overall heart disease risk, the study volunteers didn’t see them the same way: 70.1 percent felt that a 50 percent lifetime risk was “high to very high,” as compared with 31.4 percent feeling at high risk when it came to a 15 percent chance of having a heart attack or stroke in 10 years and 25.7 percent perceiving high risk in a 4 percent risk of a heart disease death in 10 years.

In all the scenarios, patients who said they perceived high or very high risk were also two to three times more likely to say they would be willing to take medication to lower that risk, the study also found.

“Once I saw these data, I changed how I speak with my patients,” Navar said. “I make sure I give them both the 10-year and lifetime risks. I also make sure I explain my interpretation of those data.”

As more and more patients want to be partners in decision-making about their health, doctors need to think more carefully about how they explain risks, said Dr. Jared Magnani of the University of Pittsburgh Medical Center in Pennsylvania.

“This is a very important study,” said Magnani, who was not involved in the new research. “When you’re talking about cardiovascular disease prevention, it’s very important that patients understand the rationale for any type of pharmacologic intervention.”

The study “found that people had a pretty limited understanding of risk,” Magnani said. “So, they naturally tended to focus on the higher percentage number as conveying the higher level of risk no matter the scope of time. This suggests to me that we need a new vocabulary for communicating with patients.”

SOURCE: bit.ly/2JKEJHf JAMA Cardiology, online November 7, 2018.