Heart patients who have a positive outlook are less likely to die in the decade after their diagnoses than those who are gloomy about their chances of recovery, a new U.S. study suggests.

Researchers at the Duke University Medical Center in Durham, N.C., found that heart patients in a study who were more optimistic were 30 to 50 per cent less likely to die in the 10 years following their diagnoses than those who are more pessimistic.

Dr. John C. Barefoot, who presented the findings at the annual meeting of the American Psychosomatic Society in Baltimore on Thursday, said the study looked at the impact of a patient's attitude toward disease.

"For patients, this means that having positive expectations can not only make you feel better but also potentially live longer," he said in a news release issued Thursday.

In the 1990s, researchers gave a psychological questionnaire to more than 2,800 patients with coronary disease. The patients were asked to assess their ability to recover from the illness and return to a regular routine. Participants included those with at least one blocked artery.

Responses to the questionnaire enabled researchers to determine whether patients felt positive about surviving heart disease.

Patients were asked to indicate how strongly they agreed or disagreed with such statements as "I am optimistic about my future and returning to a normal life" and "My heart condition will have little or no effect on my ability to do work," according to ABC News Online.

In 2002, six to 10 years after the patients had enrolled in the study, 978 had died. Of those deaths, 66 per cent were the result of coronary disease.

Dr. Redford Williams, director of the behavioural medicine research centre at the Duke University Medical Center, told CBC News that the most optimistic patients were anywhere from 30 to 50 per cent less likely to die over the 10-year period than the least optimistic patients.

He said the study compared the top quarter of the patients, who were most optimistic, with the bottom, least-optimist quarter of the group.

Even when the researchers adjusted the data to account for such factors as depression and social isolation, the more optimistic patients had better outcomes, he said.

The researchers suggested the results might be in part because people with positive attitudes would be more likely to engage in coping behaviours, such as taking medicine as directed by a doctor. They also said positive thoughts may lessen the damaging effects of stress on the body.

Barefoot told the annual meeting that the study results are useful for physicians. He said doctors need to take into account the role of attitudes in the recovery process of their patients.

Past studies have looked at how expectations affect a patient's ability to engage in daily activities, but he said this study went further because it showed that overall outlook can have an impact on physical health.

"We already know that there is a relationship between depression and increased rates of mortality," Barefoot said.

"These findings demonstrate the magnitude of the impact of patient expectations on the recovery process regardless of other psychological or social factors."
 
Barefoot said the higher risk of death, resulting from a more pessimistic outlook, remained consistent despite several factors, including the severity of the disease, age, gender, income, symptoms of depression and ability to complete routine tasks.

He said further research is needed to determine exactly how positive expectations affect disease survival.