Hypertension Is Not the Link Between Job Strain and Coronary Heart Disease in the Whitehall II Study

Background Hypertension is assumed to be one of the mechanisms through which job strain (a combination of high work demands and low job control) increases coronary heart-disease risk. However, direct tests of this hypothesis are lacking. Methods We examined whether hypertension mediated the association between job strain and incident coronary heart disease among 5630 men and 2456 women free of coronary heart disease at study entry. Job strain was assessed at phase 1 (1985 to 1988); hypertension and systolic and diastolic blood pressure (BP) were assessed at phases 1, 3 (1992 to 1993), and 5 (1997 to 1999); and incident coronary heart disease was assessed from the end of phase 1 to phase 7 (2003 to 2004) (698 events; median follow-up, 16.1 years). Results After adjustment for age, sex, ethnicity, and employment grade, job strain was associated with an increased incidence of coronary heart disease. Further adjustments, for hypertension, systolic BP, and diastolic BP at phase 1 and across phases 1, 3, and 5, and the slope of hypertension and BP over time, had little effect on this association, although measures of hypertension and BP were strongly related to incident coronary heart disease. Conclusions Data, including repeated casual measurements of hypertension and BP, suggest that the development of chronic hypertension is not a key mechanism linking job strain and coronary heart disease. Further research on ambulatory measurements is needed to determine whether episodic BP elevations have a role in this association