Töres Theorell

Job decision latitude, job demands, and cardiovascular disease: a prospective study of Swedish men.

The association between specific job characteristics and subsequent cardiovascular disease was tested using a large random sample of the male working Swedish population. The prospective development of coronary heart disease (CHD) symptoms and signs was analyzed using a multivariate logistic regression technique. Additionally, a case-controlled study was used to analyze all cardiovascular-cerebrovascular (CHD-CVD) deaths during a six-year follow-up. The indicator of CHD symptoms and signs was validated in a six-year prospective study of CHD deaths (standardized mortality ratio 5.0; p less than or equal to .001). A hectic and psychologically demanding job increases the risk of developing CHD symptoms and signs (standardized odds ratio 1.29, p less than 0.25) and premature CHD-CVD death (relative risk 4.0, p less than .01). Low decision latitude-expressed as low intellectual discretion and low personal schedule freedom-is also associated with increased risk of cardiovascular disease. Low intellectual discretion predicts the development of CHD symptoms and signs (SOR 1.44, p less than .01), while low personal schedule freedom among the majority of workers with the minimum statutory education increases the risk of CHD-CVD death (RR 6.6, p less than .0002). The associations exist after controlling for age, education, smoking, and overweight.

Current issues relating to psychosocial job strain and cardiovascular disease research.

: The authors comment on recent reviews of cardiovascular job strain research by P. L. Schnall and P. A. Landsbergis (1994), and by T. S. Kristensen (1995), which conclude that job strain as defined by the demand-control model (the combination of contributions of low job decision latitudes and high psychological job demands) is confirmed as a risk factor for cardiovascular mortality in a large majority of studies. Lack of social support at work appears to further increase risk. Several still-unresolved research questions are examined in light of recent studies: (a) methodological issues related to use of occupational aggregate estimations and occupational career aggregate assessments, use of standard scales for job analysis and recall bias issues in self-reporting; (b) confounding factors and differential strengths of association by subgroups in job strain-cardiovascular disease analyses with respect to social class, gender, and working hours; and (c) review of results of monitoring job strain-blood pressure associations and associated methodological issues.

Job characteristics in relation to the prevalence of myocardial infarction in the US Health Examination Survey (HES) and the Health and Nutrition Examination Survey (HANES).

Associations between psychosocial job characteristics and past myocardial infarction (MI) prevalence for employed males were tested with the Health Examination Survey (HES) 1960-61, N = 2,409, and the Health and Nutrition Examination Survey (HANES) 1971-75, N = 2,424. A new estimation method is used which imputes to census occupation codes, job characteristic information from national surveys of job characteristics (US Department of Labor, Quality of Employment Surveys). Controlling for age, we find that employed males with jobs which are simultaneously low in decision latitude and high in psychological work load (a multiplicative product term isolating 20 per cent of the population) have a higher prevalence of myocardial infarction in both data bases. In a logistic regression analysis, using job measures adjusted for demographic factors and controlling for age, race, education, systolic blood pressure, serum cholesterol, smoking (HANES only), and physical exertion, we find a low decision latitude/high psychological demand multiplicative product term associated with MI in both data bases. Additional multiple logistic regressions show that low decision latitude is associated with increased prevalence of MI in both the HES and the HANES. Psychological workload and physical exertion are significant only in the HANES.

Long-term psychosocial work environment and cardiovascular mortality among Swedish men.

OBJECTIVES This study examined the effect of cumulative exposure to work organization--psychological demands, work control, and social support on prospectively measured cardiovascular disease mortality risk. METHODS The source population was a national sample of 12517 subjects selected from the Swedish male population by Statistics Sweden in annual surveys between 1977 and 1981. Over a 14-year follow-up period, 521 deaths from cardiovascular disease were identified. A nested case-control design was used. Work environment exposure scores were assigned to cases and controls by linking lifetime job histories with a job exposure matrix. RESULTS Conditional logistic regression analysis was used in examining cardiovascular mortality risk in relation to work exposure after adjustment for age, year last employed, smoking, exercise, education, social class, nationality, and physical job demands. In the final multi-variable analysis, workers with low work control had a relative risk of 1.83 (95% confidence interval [CI] = 1.19, 2.82) for cardiovascular mortality. Workers with combined exposure to low control and low support had a relative risk of 2.62 (95% CI=1.22, 5.61). CONCLUSIONS These results indicate that long-term exposure to low work control is a risk factor for cardiovascular disease mortality.

Effect of change in the psychosocial work environment on sickness absence: a seven year follow up of initially healthy employees

STUDY OBJECTIVE To investigate the impact of changes in psychosocial work environment on subsequent sickness absence. DESIGN Analysis of questionnaire and sickness absence data collected in three time periods: 1990–1991, before the recession; 1993, worst slump during the recession; and 1993–1997, a period after changes. SETTING Raisio, a town in south western Finland, during and after a period of economic decline. PARTICIPANTS 530 municipal employees (138 men, 392 women) working during 1990–1997 who had no medically certified sick leaves in 1991. Mean length of follow up was 6.7 years. MAIN RESULTS After adjustment for the pre-recession levels, the changes in the job characteristics of the workers during the recession predicted their subsequent sick leaves. Lowered job control caused a 1.30 (95% CI = 1.19, 1.41) times higher risk of sick leave than an increase in job control. The corresponding figures in relation to decreased social support and increased job demands were 1.30 (95% CI = 1.20, 1.41) and 1.10 (95% CI = 1.03, 1.17), respectively. In some cases there was an interaction with socioeconomic status, changes in the job characteristics being stronger predictors of sick leaves for employees with a high income than for the others. The highest risks of sick leave (ranging from 1.40 to 1.90) were associated with combined effects related to poor levels of and negative changes in job control, job demands and social support. CONCLUSION Negative changes in psychosocial work environment have adverse effects on the health of employees. Those working in an unfavourable psychosocial environment before changes are at greatest risk.

Decision latitude, job strain, and myocardial infarction: a study of working men in Stockholm. The SHEEP Study Group. Stockholm Heart epidemiology Program.

OBJECTIVES This study examined the role of decision latitude and job strain in the etiology of a first myocardial infarction. METHODS Eligible case patients were all full-time working men 45 to 64 years of age who suffered a first myocardial infarction during the period January 1992 to January 1993 in the greater Stockholm region. Referents were selected from the general population. Participation rates were 82% (case patients) and 75% (referents). RESULTS Both inferred and self-reported low decision latitude were associated with increased risk of a first myocardial infarction, although this association was weakened after adjustment for social class. A decrease in inferred decision latitude during the 10 years preceding the myocardial infarction was associated with increased risk after all adjustments, including chest pain and social class. The combination of high self-reported demands and low self-reported decision latitude was an independent predictor of risk after all adjustments. CONCLUSIONS Both negative change in inferred decision latitude and self-reported job strain are important risk indicators in men less than 55 years of age and in blue-collar workers.

Myocardial infarction risk and psychosocial work environment: An analysis of the male Swedish working force

The project was designed to test the assumption that certain psychosocial characteristics of occupational groups are associated with elevated myocardial infarction risk. All cases of myocardial infarction below the age of 65 in men living in the region of greater Stockholm during the years 1974-1976 were identified (deaths as well as survivals) in the official registries of hospitalizations and deaths. For each case two controls without infarction (in younger ages four) matched for age, area of residence and sex were selected randomly from the parish registries. For each case and control (n = 334 and 882, respectively) information was available regarding occupation. The psychosocial characteristics of each one of the 118 occupations were recorded by means of a nation wide interview survey (3876 working men) in 1977. Relative age-adjusted risks of developing a myocardial infarction were calculated for occupations in which many vs occupations in which few subjects reported a given characteristic (50% with most vs 50% with least). Shift work and monotony were associated with significant excess risk. Hectic work was not associated with excess risk by itself but in combination with variables associated with low decision latitude and/or few possibilities for growth it was associated with significant excess risk.

High effort, low reward, and cardiovascular risk factors in employed Swedish men and women: baseline results from the WOLF Study.

STUDY OBJECTIVE: To examine associations between measures of work stress (that is, the combination of high effort and low reward) and cardiovascular risk factors. DESIGN: Cross sectional first screening of a prospective cohort study. SETTING AND PARTICIPANTS: The study was conducted among 5720 healthy employed men and women living in the greater Stockholm area aged 19-70 years. All analyses were restricted to subjects with complete data (n = 4958). The investigation of associations between indicators of effort-reward imbalance and cardiovascular risk factors was restricted to the age group 30-55 years (n = 3427). MAIN RESULTS: Subjects reporting high effort and low reward at work had a higher prevalence of well known risk factors for coronary heart disease. After adjustment for relevant confounders, associations between a measure of extrinsic effort and reward (the effort-reward ratio) and hypertension (multivariate prevalence odds ratio (POR) 1.62-1.68), increased total cholesterol (upper tertile 220 mg/dl)(POR = 1.24) and the total cholesterol/high density lipoprotein(HDL)-cholesterol ratio (upper tertile 4.61)(POR 1.26-1.30) were found among men. Among women a measure of high intrinsic effort (immersion) was related to increased low density lipoprotein (LDL)-cholesterol (upper tertile 130 mg/dl)(POR 1.37-1.39). Analyses of variance showed increasing mean values of LDL cholesterol with an increasing degree of the effort-reward ratio among men and increased LDL-cholesterol among women with high levels of intrinsic effort (upper tertile of immersion). CONCLUSIONS: Findings lend support to the hypothesis that effort-reward imbalance represents a specific constellation of stressful experience at work related to cardiovascular risk. The relation was not explained by relevant confounders (for example, lack of physical exercise, body weight, cigarette smoking).

Psychosocial work environment and myocardial infarction: improving risk estimation by combining two complementary job stress models in the SHEEP Study

Objectives: Associations between two alternative formulations of job stress derived from the effort-reward imbalance and the job strain model and first non-fatal acute myocardial infarction were studied. Whereas the job strain model concentrates on situational (extrinsic) characteristics the effort-reward imbalance model analyses distinct person (intrinsic) characteristics in addition to situational ones. In view of these conceptual differences the hypothesis was tested that combining information from the two models improves the risk estimation of acute myocardial infarction. Methods: 951 male and female myocardial infarction cases and 1147 referents aged 45–64 years of The Stockholm Heart Epidemiology (SHEEP) case-control study underwent a clinical examination. Information on job stress and health adverse behaviours was derived from standardised questionnaires. Results: Multivariate analysis showed moderately increased odds ratios for either model. Yet, with respect to the effort-reward imbalance model gender specific effects were found: in men the extrinsic component contributed to risk estimation, whereas this was the case with the intrinsic component in women. Controlling each job stress model for the other in order to test the independent effect of either approach did not show systematically increased odds ratios. An improved estimation of acute myocardial infarction risk resulted from combining information from the two models by defining groups characterised by simultaneous exposure to effort-reward imbalance and job strain (men: odds ratio 2.02 (95% confidence intervals (CI) 1.34 to 3.07); women odds ratio 2.19 (95% CI 1.11 to 4.28)). Conclusions: Findings show an improved risk estimation of acute myocardial infarction by combining information from the two job stress models under study. Moreover, gender specific effects of the two components of the effort-reward imbalance model were observed.

Shiftwork and myocardial infarction: a case-control study

OBJECTIVES: Previous studies have indicated an association between shiftwork and coronary heart disease. The increased risk could be due to job strain, which could act as a mediator of disease. There is also a possibility that interaction between shiftwork and job strain could occur that may induce or modify the development of disease. We conducted this study to explore the relation between shiftwork, job strain, and myocardial infarction. METHODS: 2006 cases with acute first time myocardial infarction were compared with 2642 controls without symptoms of myocardial infarction, and obtained from the same population that gave rise to the cases (population based case-control study). RESULTS: Myocardial infarction risk was associated with shiftwork both in men (odds ratio (OR) 1.3, 95% confidence interval (95% CI) 1.1 to 1.6) and women (OR 1.3, 95% CI 0.9 to 1.8). In the age group 45-55, the relative risk was 1.6 in men and 3.0 in women. The results cannot be explained by job strain, age, job education level, or smoking. No interaction was found between shiftwork and job strain. CONCLUSIONS: The findings indicate that shiftwork is associated with myocardial infarction in both men and women. The mechanism is unclear, but the relation cannot be explained by job strain, smoking, or job education level.