It has been proposed that the impact of job strain (high demand / low control) on coronary heart disease and hypertension is mediated by heightened cardiovascular and neuroendocrine stress responsivity. However, studies using standardized mental stress testing have not shown differences in responsivity between low and high job strain groups. We tested the hypothesis that people experiencing high job strain would be especially responsive to uncontrollable stressors, but not to controllable behavioral demands. We also assessed ambulatory blood pressure and heart rate, predicting that high job strain individuals would show deficits in homeostatic regulation, leading to a failure to "unwind" after work.
Participants were 162 school teachers (60 men, 102 women), selected from a survey of 755 teachers as reporting high or low job strain. Blood pressure, heart rate, skin conductance and cortisol responses controllable (self-paced) and uncontrollable (externally paced) computerised tasks were recorded under standardized conditions. Blood pressure and heart rate were monitored from 9:00 am - 10:30 pm on a working day and subsequent evening.
High and low job strain groups did not differ in demographic factors, body mass or resting cardiovascular activity. Blood pressure reactions to the uncontrollable task were significantly greater in high than low job strain groups. Phsyiological responses to the controllable task were not significantly different between job strain groups, even though the range of individual responses was similar for the two tasks. Systolic and diastolic blood pressure over the working day was similar in the two groups. However, blood pressure decreased in the evening to a greater extent in the low job strain participants, The maintenance of blood pressure levels from the day to evening in the high strain group was independent of age, body mass index, posture and resting blood pressure. Subjective ratings taken at the same time as blood pressure measures showed greater self-reported pressure and lower control in the teachers with high job strain.
These data highlight ways in which psychophysiological responses may mediate the impact of work experience on cardiovascular disease risk. People experiencing high job strain may be selectively responsive physiologically to experiences on cardiovascular disease risk. People experiencing high job strain may be selectively responsive physiologically to experiences that are perceived as uncontrollable, and show failures to unwind after work that contribute to risk.
Introduction: Job Strain (high psychological demand and low decision latitude) is associated with an increased risk for myocardial infarction (MI). In the WOLF study (Work Lipids and Fibrinogen) the relationship of job stain to hypertension, serum lipids and plasma fibrinogen is being studied as these factors are risk factors for MI.
Method: In this part of the WOLF study individual evaluation of psychological demands and decision latitude at the work place (self-administered questionnaire, 6 questions on "decision latitude" and 5 on "demand") ad well as the responding external evaluation by the local occupational health unit (3 questions on "decision latitude", 2 on "demand") were related to blood pressure, serum lipids and plasma fibrinogen.
Results: Altogether 3807 workers (2275 men, 1532 women) were included in this evaluation. Externally rated decision latitude showed a highly significant positive correlation with the individual evaluation index (R2=.31 for men, .24 for women. p<.001. Linear regression, contr. f. age). External rating of psychological demands was not strongly but positively associated with the individual scores (p<.001). In general, higher correlations were found for men, younger and blue collar workers. Individual and external ratings mostly showed similar tendencies when the prevalence ratio (PR, cont. f. age, body mass index and smoking) was calculated for adverse blood lipids and fibrinogen, particularly in men. Those with job strain did not have a consistently more adverse risk profile when compared with those with high decision latitude and low demands. Men with both high decision latitude and high job demands ("active") had an increased risk for an adverse ldl/hdl ratio (external evaluation: PR 1.5, 95%CI 1.1-1.9) and showed a tendency towards high fibrinogen and a high apolipoproteinB/A1 ratio. Similar tendencies were found in women. For men who were externally rated to be exposed to job strain but did not report this themselves, lower PRs for an adverse ldl/hdl ratio (.7[.5-1.0]) and high blood pressure (.6[.4-.9]) were found.
Conclusions: External evaluation of psychosocial working conditions correlates well with individual ratings when concerning decision latitude but less so demand. Our results do not support a strong association of high job strain with an adverse blood lipid profile or with high fibrinogen. The associations found were weak but were more pronounced when external rating was applied.
Some studies have suggested that the effect of job strain on CVD is greater among men who are older, have higher blood pressure, have lower social support, or have lower socioeconomic status (SES). We tested this hypothesis in a sample of 285 healthy male employees, aged 30-60 at initial recruitment, at 8 New York City work sites, 195 of whom were restudied 3 years after their initial participation. Mean systolic (SAmBP) and diastolic (DAmBP) ambulatory blood pressure at work, home and during sleep were computed from 24-hour recordings and diary entries specifying location. Multiple regression analysis was used to examine the cross-sectional and prospective associations of AmBP with job strain, controlling for age, body mass, race/ethnicity, smoking, alcohol consumption, education, and physical exertion on the job. Interaction terms were computed by multiplying job strain by age, hypertensive status at Time 1 (>85 mm Hg clinic DBP on 2 separate occasions), coworker and supervisor support, years of education, occupational status (scale of 1-99), occupational category (white-collar; clerical, technical or administrative; blue-collar) and personal and family income.
The association of job strain and AmBP at Time 1 was much stronger among older men. Compared to 30-40 year olds without job strain, 51-60 year olds with job strain had 18.7 mm Hg higher SAmBP, but 30-40 year olds with job strain had only 0.8 mm Hg higher SAmBP (interaction term: p=.02). The job strain-AmBP association at Time 1 was also much stronger among men with mild hypertension. Compared to controls without job strain, cases with job strain had 18.5 mm Hg higher SAmBP, but controls with job strain had only 0.4 mm Hg higher SAmBP (interaction term: p=.006). The job strain-AmBP association at Time 1 was also somewhat stronger among men with lower SES. For example, compared to men with a college degree without job strain, men with only a high school degree or less and with job strain had 7.2 mm Hg higher SAmBP, but college graduates with job strain had only 2.6 mm Hg higher SAmBP (interaction term: p=.08). No significant main effects of workplace social support nor any significant interactions between job strain and social support were observed. Similar interaction effects were observed for change in AmBP over 3 years.
Among blue collar workers generally, stress has not been well studied. Risk factors for stress in this group and, in turn, the extent to which stress itself serves as a risk factor for other adverse health outcomes are not clear. The present study was carried out to examine baseline and follow-up health status and outcome in workers on a large highway construction project in the Northeastern United States.
An integrated data system that includes both primary and secondary databases has been created to evaluate stress, cardiovascular and respiratory illness and disease, and accidents and injuries among laborers, tunnel workers, and operating engineers (OE) on this construction project. Primary data is obtained from baseline and annual follow-up union-based health surveys of these trades. Secondary databases are: workers' compensation (WC) claims from 1992 and union health and welfare fund (HWF) claims from 1994. Denominator data of hours worked (as person-years) is used to calculate rates for claims by type for WC and by ICD-9 code for HWF.
In the longitudinal health survey, in addition to a detailed health and exposure history, questionnaires were used to measure psychological stress: Kellner Symptom Questionnaire (KSQ), 96 item self-report scale measuring anxiety, hostility, depressive symptoms, total distress; and Karasek Job Content Questionnaire (KJCQ), evaluating psychological job demands and decision latitude, as well as job strain (decision latitude/psychological demand).
A total of 296 workers has been examined to date. (Laborers = 132, tunnel workers = 45, and OE's = 119. Most are white (87%) males (90%) married (60%) with mean age of 41 years and duration of work 12 years. KJCQ subscales raw scores did not differentiate job trade or union local, while the use of job strain category did. KSQ raw scores did not differentiate job trade or union local, except for small but significant differences of hostility and total distress differentiating union locals. This difference was much more robust when evaluating the frequency of workers in different trades and locals with a level of total distress or hostility above a prior predetermined clinically relevant level (relative risks 2.5-3.0). Evaluating average KSQ scores by KJCQ job strain category was not useful except for mild mean elevations psychological symptoms in the high job strain group (low decision latitude/high psychological demand). All workers with different job stress levels measured by KJCQ job strain categories and evaluated for the frequency of those workers with significant levels of psychological symptomatology demonstrated dramatic differences somatic, depressive, and hostility symptoms. Finally, a pilot evaluation of workers with significant depressive symptoms appear to have elevated levels risk factors and prevalence of cardiovascular disease.
This preliminary data suggests that there are significant differences in the frequency of job strain and clinically significant psychological symptomatology in subgroups of workers not explained by job classification. Various hypotheses explaining these differences will be offered. For the workers in aggregate, the level of job strain is strongly related tot he frequency of clinically relevant levels of psychological symptoms.
This research funded by: Center to Protect Workers' Rights/NIOSH
Purpose: ‘Job strain’ (defined as high demands and low control) has been previously associated with increased risk of cardiovascular disease (CVD) and, cross-sectionally, with hypertension and elevated ambulatory blood pressure (AmBP). Our longitudinal cohort study was designed to investigate the hypothesis that exposure to ‘job strain’ is causally related to increases in mean AmBP.
Methods: The sample consists of 285 healthy male employees, aged 30-60 at initial recruitment, at 8 New York City worksites, 195 of whom were restudied 3 years after (Time 2) and 195 of whom were restudied 6 years after (Time 3) their initial participation. Mean systolic (SAmBP) and diastolic (DAmBP) ambulatory blood pressure at work, home and during sleep were computed from 24-hour recordings and diary entries specifying location. The relationship of ‘job strain’ to AmBP was examined cross-sectionally at each round of data collection. A ‘job strain’ change variable was constructed with four categories: those defined as having no ‘job strain’ at either Time 1 or Time 2 (N=138), those reporting ‘job strain’ at both times (N=15), and two groups which changed ‘job strain’ status. We repeated this analysis comparing Times 1 and 3 and Times 2 and 3. Multiple regression analysis was used to examine the cross-sectional associations of AmBP with ‘job strain’, as well as to predict 3 year and 6-year change in AmBP with ‘job strain’ change, controlling for age, body mass, race/ethnicity, smoking status, alcohol consumption, education, sodium and physical exertion level of the job.
Results: Cross-sectional analyses at Time’s 1, 2 & 3 showed consistent significant effects of ‘job strain’ on AmBP. With subjects reporting ‘job strain’ having work SAmBP/DAmBP which were 5-7/3-5 mm Hg higher than subjects without ‘job strain’. Men facing chronic ‘job strain’, that is working in high strain jobs at both Time 1 and Time 2 had work SAmBP/DAmBP on average, 10-12/6-8 mm Hg higher than those with no ‘job strain’ at both times. In longitudinal analyses, subjects who changed from exposure to ‘job strain’ to no exposure three or six years later had a decrease in SAmBP/DAmBP of about 5/3 mm Hg.
Conclusions: The previously reported cross-sectional association between ‘job strain’ and AmBP was replicated twice during follow-up periods. Repeated exposure to ‘job strain’ was associated with the highest levels of AmBP’s, but not with any further increases in AmBP. However, changes in ‘job strain’ status predicted change in AmBP over three and six year periods. ‘Job strain’ emerges as a consistent and substantial risk factor for AmBP in men.