Nearly one in five people with the highest heart attack risk don’t believe they need to improve their health, according to a Canadian study.

Among 45,443 adults participating in the 2011-12 Canadian Community Health Survey, 17.7 percent at greatest risk (five or more risk factors) didn’t feel they needed to improve their health and more than half of the 73.6 percent who said they needed health improvements identified barriers to change, most commonly lack of self-discipline, work schedule and family responsibilities.

Researchers also found that 90.7 percent of those identifying a specific change indicated they wanted to quit/reduce smoking, exercise more, lose weight or eat better, and 81.1 percent desiring a change said they intended to improve their health in the coming year.

“Understanding what motivates changes in behavior is key to improving the health of individuals and communities,” said F. Daniel Ramirez, M.D., a research fellow at the University of Ottawa Heart Institute in Ottawa, Ontario, Canada.

Respondents with high blood pressure or diabetes also weren’t more likely to perceive the need to improve their health than those without those conditions. The survey didn’t include information about whether this group took medications to control these health problems, which may have affected their perceptions about the need to improve their health.

Still, “lifestyle modifications are very important for these conditions, particularly diabetes, even for those on medications,” said Benjamin Hibbert, M.D., Ph.D., an interventional cardiologist and assistant professor at the University of Ottawa Heart Institute.

For the study, researchers gathered information about eight risk factors for heart attack that people can change: smoking, high blood pressure, diabetes, obesity, stress, excessive alcohol consumption, lack of physical activity and poor diet. Along with high cholesterol, which was not included in the survey, the factors account for 90 percent of heart attack risk.

Researchers also looked at factors that might bias results, including age, education, income and whether respondents had a regular healthcare provider. After adjusting for these factors, researchers found that older and white participants were more likely than younger and minority group members to express a desire to improve their health.

Despite many similarities between Canada and the United States, researchers couldn’t say whether differences in healthcare systems and culture would limit generalizing study findings to the United States.

The study is reported in the Journal of the American Heart Association.