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Work stress and risk of cardiovascular mortality: prospective cohort study of industrial employees

BMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7369.857 (Published 19 October 2002) Cite this as: BMJ 2002;325:857

Rapid Response:

CONFOUNDERS AND INTERMEDIATE VARIABLES

Sir,

I found the paper contributes largely to the understanding of the
stress-occupation relationship. However, its lectures raises several
questions which I would like to formulate to you:

1-Are you satisfied with the magnitude of the hazards rates you
obtain for those risk definitively associated to cardiovascular disease.
It appears to me that a hazard rate over 6 for blood pressure larger than
143 is high, unless most of the deaths were stroke. And it also appear to
me that a hazard rate of almost 6 for cholesterol larger than 6.8 mm/l
is also large, more over if there are also stroke cases. I you agree that
these hazard rates are high, they could occur if the population is very
susceptible, or they are confounded by other factors ( occupation?) or
they are biased.

2-You state that “However, high job strain and high effort-reward
imbalance were associated with increased cholesterol concentration and
body mass index at follow up. These associations may reflect
pathophysiological changes related to the development of cardiovascular
disease”. In other words, these two variables would be considered part of
the causal pathway stress-cardiovascular disease. Therefore, adjusting for
them, as in table 3, would result in, at least partially, blunting of the
association, which does not occur.

3-It is interesting and a bit surprising that high blood pressure was
not associated to indicators of stress, while it was cholesterol and body
mass index.

4-It would be interesting to consider the incubation period for
stress: How long, in terms of dose and time, has this hazard to act as to
produce the expected results? And, How long since the dose has accumulated
as to trigger the disease, do we have to wait to collect the events
attributable to the exposure?. In other words, are these results
attributable to the exposure examined in 1973?.

Thank you very much.

M Caicoya

Competing interests: No competing interests

28 October 2002
MARTIN CAICOYA
HEAD OF OOCUPATIONAL HELATH SERVICE. PRICIPADO DE ASTURIAS. SPAIN
HOSPITAL MONTE NARANCO. HERMANOS VEGAS/N. 33012 OVIEDO. SPAIN