PARIS — Workers who suffer job strain are 23-percent more likely to have a heart attack than stress-free counterparts, but the risk is far smaller than smoking or a sedentary lifestyle, a large study published in The Lancet on Friday says.

“Job strain is asociated with a small, but consistent, increased risk of experiencing a first CHD (coronary heart disease) event such as a heart attack,” said Mika Kivimaki, an epidemiologist at University Collegef London who led the probe.

The investigation seeks to shed light on an issue that has turned up confusing results, mainly because researchers have used different definitions and varying methods.

The new paper is a meta-analysis — an overview of 13 studies conducted between 1985 and 2006 in seven European countries that adopted the same approach: participants without CHD were first interviewed and their health was then monitored, for 7.5 years on average.

In all, 197,473 took part in these studies, of whom 30,214 reported job strain, defined as having excessive workloads, time pressures and little freedom to make decisions at work.

During the monitoring period that followed, doctors recorded 2,356 heart attacks, fatal or otherwise.

The risk was 23 percent higher among the “job strain” group, even when age, gender and socio-economic factors, which all influence risk, were taken into account.

Three studies each took place in Denmark and Finland, two each were conducted in the Netherlands and Sweden, and the others were carried out in Belgium, Britain and France.

The authors say the findings are significant. But they also note that prevention of workplace stress to reduce heart disease would be much less effective than efforts to combat smoking and physical inactivity, where the risk of CHD is more than 10 and nearly four times greater respectively.

In a commentary also carried by The Lancet, Bo Netterstrom of Bispelbjerg Hospital in Copenhgean cautioned that work-related health problems in Europe “will almost certainly increase” because of job insecurity driven by the economic crisis.