Chronic tension between spouses can raise the risk of heart disease by 25%, and high job stress can double the risk of a second heart attack or unstable angina, according to two separate studies published this week.
The reports confirm what doctors have long suspected -- that chronic stress in these two areas of adult life play a key role in heart health and must be closely monitored, just like weight, blood pressure and cholesterol.
Dr. Kristina Orth-Gomer of the Karolinska Institute in Sweden, who wrote an editorial accompanying one of the studies, said doctors ought to recognize stress as a significant risk factor and talk with their patients about it.
Although the topic may seem awkward, she said, "in my experience . . . patients are very relieved to start talking and the conversation may be just the therapy" they need.
The job-stress study, published today in the Journal of the American Medical Assn., looked at 866 men and 106 women from 30 hospitals around the Canadian province of Quebec who returned to work for at least 10 hours a week within 18 months of a first heart attack. Researchers, led by Dr. Corine Aboa-Eboule of Laval University in Montreal, tracked the participants for six years.
Participants, ages 35 to 59, answered questions about job stress at the beginning of the study, after two years and at six years. Stress was determined by factors including quantity of work, intellectual requirements, time constraints and the latitude to make decisions, be creative and develop or acquire skills.
Researchers found that jobs with high demands and little autonomy carried the most stress, and that people in those jobs tended to be female, less educated, less physically active and more likely to smoke than people in low-stress jobs.
The study found no increased risk associated with job stress during the first two years of the study. Coauthor Dr. Alain Milot of Laval University said researchers surmised it would take more than two years for the effects of chronic stress to develop, a factor that may help explain why some short-term studies have found no association between heart disease and job stress.
Exactly how stress affects the cardiac system isn't known. But researchers speculated that chronic job strain activates a complex hormonal system, increasing arterial inflammation and forming clots. A heart attack occurs when a clot blocks an artery, cutting off blood flow.
In a subanalysis of the data, researchers said job stress seemed particularly bad for 80 people whose ejection fraction, or amount of blood pumped with each heartbeat, was 40% of normal.
They faced eight times the risk of a second heart attack or angina. Researchers said the result needed to be confirmed by further study.
In addition, Orth-Gomer said it was not clear whether the overall findings could be generalized to women because the number of females in the study was relatively small and her own research found that job stress had little effect on middle-age women. One problem in finding women for such studies is that heart attacks are less common in younger women than in younger men.
The second report, published Monday in the journal Archives of Internal Medicine, tracked 6,114 male and 2,897 female British civil servants for 12 years.
Lead author Roberto De Vogli, an epidemiologist with University College London, said the added risk associated with marital stress was small compared with the effects of such established risk factors as obesity, high blood pressure, diabetes and high cholesterol.
Nonetheless, he said, it was important for patients to know that marital stress may increase their chances of developing heart disease.
At the start of the study, participants completed questionnaires about their intimate relationships and overall health. They were asked, for example, whether talking with their spouse made things worse and increased their anxiety and worry. They also were asked whether they could confide in their spouse and if the spouse provided practical support and help when they needed it.
Researchers found that an inability to confide in a spouse or a lack of support from a partner had no effect on heart disease risk.
But participants who said their spouses increased their anxiety and generally made things worse were at greater risk, even when a long list of established risk factors, including hypertension, smoking and lack of exercise, and psychological conditions such as depression, were taken into account.
Stressful marriages affected men and women equally, although more women than men reported having a poor relationship with their spouse. Smaller, previous studies had found that husbands were not as susceptible to marital stress as wives.