Association between ambulatory blood pressure and alternative formulations of job strain.

OBJECTIVES: The goal of the study was to determine whether alternative formulations of Karasek & Theorell's job-strain construct are associated with ambulatory blood pressure and the risk of hypertension. METHODS: Full-time male employees (N = 262) in eight worksites completed a casual blood pressure screening, medical examinations, and questionnaires and wore an ambulatory blood pressure monitor for 24 h on a workday. Cases of hypertension were ascertained from casual blood pressure readings for a case-referent analysis. A cross-sectional analysis was also conducted, ambulatory (continuous) blood pressure measurements being used as the outcome. RESULTS: All formulations of job strain exhibited significant associations with systolic blood pressure at work and home, but not with diastolic blood pressure. Employees experiencing job strain had a systolic blood pressure that was 6.7 mm Hg (approximately 0.89 kPa) higher and a diastolic blood pressure that was 2.7 mm Hg (approximately 0.36 kPa) higher at work than other employees, and the odds of hypertension were increased odds ratio (OR) 2.9, 95% confidence interval (95% CI) 1.3-6.6. Using national means for decision latitude and demands to define job strain increased the systolic and diastolic blood pressure associations to 11.5 mm Hg (approximately 1.53 kPa) and 4.1 mm Hg (approximately 0.54 kPa), respectively. Adding organizational influence to the task-level decision latitude variable produced a stronger association for hypertension with job strain (OR 3.7, 95% CI 1.6-8.5). Adding social support to the job-strain model also slightly increased the hypertension risk. CONCLUSIONS: The impact of job strain, at least on systolic blood pressure, is consistent and robust across alternative formulations, more restrictive cut points tending to produce stronger effects.