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Am Fam Physician. 2008;78(1):115-116

Background: Many studies have shown that job strain, defined by psychological stress and limited decision-making latitude, increases cardiac risk. However, the effect of job strain on recurrent cardiac events is less clear. Aboa-Éboulé and colleagues studied a large cohort of patients with prior myocardial infarctions (MIs) to determine whether job strain was associated with subsequent coronary heart disease (CHD) events.

The Study: Patients 59 years or younger who were recently hospitalized for MI were recruited from multiple centers. Only those who held a job in the year preceding their MI and who planned to return to work were eligible. Of 1,191 recruits, 972 met the criteria. Baseline history and physical information were retrieved from documentation completed at the initial hospitalization. On average, patients were interviewed by phone six weeks after returning to work, 2.2 years later, and at 6.9 years. The first two interviews assessed demographics, psychosocial factors, and CHD risk factors; the third interview assessed hospital readmissions.

Outcome measures were a composite of fatal CHD, nonfatal MI, and unstable angina. Job strain was assessed using the Karasek Job Content Questionnaire. In addition, job strain was dichotomized, based on a sample of the general population and then further divided into four categories: high strain (high psychological demands and low decision-making latitude), active strain (high psychological demands and high decision-making latitude), passive strain (low psychological demands and low decision-making latitude), and low strain (low psychological demands and high decision-making latitude). The latter three groups were also categorized as non–high strain in order to compare high-strain and non–high strain groups.

Results: Of the 972 patients returning to work after their initial MI, 22 did not respond after the baseline interview and 30 did not respond after the second interview. During the mean follow-up period of 5.9 years, 206 participants had a confirmed CHD event. The high-strain group differed from the non–high-strain group in patient sex, education, smoking status, family history of premature CHD, physical activity, and social support at work. Therefore, factors other than job strain influenced the risk of subsequent MI. Overall, high job strain at baseline did not correlate with the risk of a CHD event. However, chronic exposure to high job strain (i.e., at baseline and the second interview) was significantly associated with lower survival rates after 2.2 years, compared with non–high job strain. Dyslipidemia, smoking status, and number of adverse work organization factors confounded the effect of chronic job strain on CHD. Post hoc analysis indicated that the negative effect of chronic job strain may be more pronounced in patients with a left ventricular ejection fraction of less than 40 percent.

Conclusion: After 2.2 years of prospective follow-up, chronic job strain was significantly associated with CHD events in middle-age patients with prior MIs. This finding persisted after adjusting for 26 possible confounding factors. Because morbidity risk is likely higher in patients with a left ventricular ejection fraction of less than 40 percent, the authors conclude that efforts should be made to reduce job strain in these high-risk patients.

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