Chronic job strain, characterized by high psychological demands and few decision-making opportunities, significantly increased the risk of recurrent coronary heart disease (CHD) events among middle-aged patients who returned to work after a heart attack. As reported in the October 10 JAMA, researchers observed the link after examining job strain as a prognostic factor following a first myocardial infarction.

“These results suggest that preventive interventions aimed at reducing job strain might have a significant impact on recurrent CHD events,” stated Corine Aboa-Éboulé, MD, PhD, of the Université Laval in Quebec City, and colleagues.

Job strain has been shown in numerous studies to increase the risk of a patient’s first CHD event; however, in two studies that investigated the potential link between job strain and recurrent events in men and women, only the study in men revealed an increased risk. Dr. Aboa-Éboulé and coauthors noted that neither of the prospective studies evaluated the duration of psychosocial work exposure and that the number of participants was small. “Not assessing duration of exposure may generate an information bias, which could lead to an underestimation of the true effect,” they stated.

ASSESSING THE AFFECTS OF JOB STRAIN

The authors aimed to address these limitations by analyzing the effect of job strain on the risk of recurrent CHD events in 972 patients ages 35 to 59 who were recruited from hospitals in Quebec. The men and women returned to work a mean 3.6 months after their first myocardial infarction and were followed up with phone interviews, conducted about six weeks after they returned to work (baseline) and approximately two and six years later. A validated French version of the Karasek Job Content Questionnaire measured the participants’ degree of job strain, defined by psychological demands (eg, quantity of work, time constraints) and decision latitude (eg, ability to make decisions and develop personal skills). Chronic job strain was classified as a high level of strain at both interviews.

During the mean follow-up of 5.9 years, 206 patients experienced a recurrent CHD event—111 cases of nonfatal myocardial infarction, 82 incidents of unstable angina, and 13 cases of fatal CHD. Although job strain at baseline was not associated with the risk of recurrent CHD, patients with chronic exposure to job strain had a twofold higher risk of recurrent events compared with those returning to a job without strain, reported the researchers. The association remained significant after adjustment for 26 potentially confounding factors and was particularly evident in patients with left ventricular systolic dysfunction (hazard ratios of chronic job strain with left ventricular ejection fraction < 40% and ≥ 40%, 8.02 and 1.80, respectively).

PSYCHOSOCIAL RISK FACTORS AND CARDIAC EVENTS

In an accompanying editorial, Kristina Orth-Gomér, MD, a Professor of Community Medicine at the Karolinska Institutet in Stockholm, noted the importance of the findings on job strain for preventive actions. She added that physicians should think twice before sending a man younger than 60 back to a job which may have threatened his life by causing his acute myocardial infarction. She also noted that the study did not assess depression, which she asserted is “perhaps the most important psychosocial risk factor.” She suggested that job strain with high psychological demand and low decision latitude may lead to chronic sleep problems and consequent depressive symptoms. Depressed mood “may be associated with abnormalities of clotting and inflammatory processes, increasing the risk for recurrent cardiac events,” she added.

Dr. Orth-Gomér also pointed out that although the study by Dr. Aboa-Éboulé and colleagues confirms that job strain increases the risk of recurrent CHD events in men, “the question about women and job strain as a prognostic factor after a first myocardial infarction is not necessarily answered.” Only 106 patients in the study were women, a number not substantial enough to validate separate analyses by sex, noted Dr. Orth-Gomér. Previous research has found that women who work full time may be less affected by job strain than are men. Instead, women have been more affected by family and social relations, especially marital stress and strain. Future studies should involve a sufficient proportion of men and women to help determine how the role of job and family strain may differ based on sex, she suggested.

—Jessica Jannicelli

Suggested Reading
Aboa-Éboulé C, Brisson C, Maunsell E, et al. Job strain and risk of acute recurrent coronary heart disease events. JAMA. 2007;298(14):1652-1660.
Orth-Gomér K. Job strain and risk of recurrent coronary events. JAMA. 2007;298(14):1693-1694.

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