The Whitehall study examined mortality rates over 10 years
among male British Civil Servants aged 20-64. The study was an
attempt to avoid some of the problems created by the use of general
social class groupings, e.g., the heterogeneity of occupations
within a single class leaves room for differing interpretations.
The Whitehall study concentrates on one "industry" in
which there is little heterogeneity within occupational grades
and clear social divisions between grades (Marmot, Kogevinas and
Elston, 1987).
An inverse association between grade (level) of employment and
mortality from CHD and a range of other causes was observed (78).
Men in the lowest grade (others = messengers, doorkeepers, etc.)
had a three-fold higher mortality rate than men in the highest
grade (administrators) (Marmot, Shipley and Rose, 1984).
Grade is also associated with other specific causes of death,
whether or not the causes were related to smoking (Marmot, Kogevinas
and Elston, 1987). While low status was associated with obesity,
smoking, less leisure time physical activity, more baseline illness,
higher blood pressure, and shorter height (78), controlling for
all of these risk factors accounted for no more than 40% of the
grade difference in CHD mortality (Marmot, Shipley and Rose, 1984;
Marmot, Kogevinas and Elston, 1987). After controlling for standard
risk factors, the lowest grade still had a relative risk of 2.1
for CHD mortality compared to the highest grade (Marmot, 1994).
One possible explanation of the remaining grade differences in
CHD mortality is grade differences in job control and job support
(Marmot, Kogevinas and Elston, 1987). In addition, blood pressure
at work was associated with "job stress", including
"lack of skill utilization", "tension", and
"lack of clarity" in tasks. The rise in blood pressure
from the lowest to the highest job stress score was much larger
among low grade men than among upper grade men. Blood pressure
at home, on the other hand, was not related to job stress level
(78).
Thus, a second longitudinal study of British Civil Servants (Whitehall
II) was initiated to investigate occupational and other social
influences on health and disease (Marmot, 1994). The final sample
was 6900 men and 3414 women aged 35-55 in the London offices of
20 civil service departments (Marmot et al., 1991). Employment
grade was strongly associated with work control and varied work
(measures of decision latitude) as well as fast pace (a measure
of job demands) (Marmot et al., 1991; Marmot, 1994). Lack of control
on the job is related to long spells of absence (> 6 days)
(Marmot, 1994).
In addition, there was no decrease in the difference in prevalence
of ischemia depending upon employment category over the 20 years
separating Whitehall I and Whitehall II (Marmot et al., 1991).
Plasma cholesterol concentrations did not differ by job category,
and the small inverse association between job status and blood
pressure in men was reduced from that seen in the Whitehall I
study. There was a significant inverse relation between BMI and
job status, but, especially in men, the differences were small.
The risk factor that differed most between employment categories
was smoking. Moderate or vigorous exercise was less common among
subjects in lower status jobs (Marmot et al., 1991).