The increased odds weren’t huge, although multiple job losses posed as big a threat as smoking, high blood pressure and other conditions that are bad for the heart.

The researchers analyzed data on more than 13,000 men and women aged 51 to 75 taking part in an ongoing health and retirement survey partly sponsored by the National Institute on Aging. Since 1992, participants have been interviewed every two years about their employment and health.

The new analysis has several limitations. The data show periods of unemployment but don’t indicate whether people were fired, laid off, out of work while switching jobs, or had voluntarily left a job. The researchers considered all of these situations “job losses,” but it’s likely the greatest risks for heart attacks were from being fired or laid off, said researcher Matthew Dupre, an assistant professor at Duke University and the lead author. Retirement was not considered unemployment

Sarah Burgard, a University of Michigan researcher who has studied the relationship between job loss and health, called the research solid but said it would be important to know the reason for the unemployment.

“There probably are differences in consequences of job loss when it’s voluntary or more or less expected” and when it comes as a sudden shock, said Burgard, who was not involved in the study.

The analysis appears in Monday’s Archives of Internal Medicine. An editorial in the journal says the study adds to decades of research linking job loss with health effects and that research should now turn to examining how and why that happens.

Theories include that the stress of losing a job may trigger a heart attack in people with clogged arteries or heart disease; and that the unemployed lose health insurance and access to medical care that can help keep them healthy, Burgard said.

The analysis covers 1992-2010. Participants were mostly in their 50s at the study’s beginning and were asked about their job history, and about employment status and recent heart attacks at subsequent interviews. People who’d had heart attacks before the study began were excluded.

Nearly 70 percent had at least one job loss, or period of unemployment after working at a job, and at least 10 percent had four or more before and/or during the study period.

There were 1,061 heart attacks during the study. Those with at least one job loss were 22 percent more likely to have a heart attack than those who never lost a job. Those with at least four job losses had a 60 percent higher risk than those with none. Men and women faced equal risks.

Even though the odds linked with job loss weren’t huge, many participants already faced increased other risks for a heart attack because of obesity, high blood pressure or lack of exercise.

“Any significant additional risk is important,” Dupre said.