Johannes Siegrist, Nico Dragano, Simone Weyers, Raimund Erbel ...

4th International Conference
on Work Environment and Cardiovascular Disease:
Newport, CA, 9 – 11 March 2005
Session ‚Social Class and Cardiovascular Disease‘
Socio-Economic
Socio Economic Status,
Work-Related
Work Related Stress
and Cardiovascular Risk:
Effect Modification
Johannes Siegrist, Nico Dragano, Simone Weyers
Department for Medical Sociology,
University of Duesseldorf

Background I:
Robust evidence of social gradient of CHD
OR CHD
4
3
2
1
0
I II III IV
Occupational grade
Marmot et al. (1978), JECH, 3: 244-249.
Determinants:
Health care system
Material deprivation
Health-related behaviour
Psychosocial stress, esp.
at work:
- Job Strain (DC)
- Effort-Reward Imbalance
(ERI)

Background II: Inconsistent evidence of social
gradient of stressful work: work:
confirmed (see see
figure) figure)
and unconfirmed findings
Effort-reward
imbalance model:
% imbalance
effort and reward
Demand-control
model:
% job strain
(observer judgement)
high,
middle,
low occupational status
80
60
40
20
0
30
20
10
0
men women
Source: Bosma et al. (1998), Am J Publ Health, 88: 70.

Background III: Reasonable evidence of an association
of stressful work (DC/ERI) with CHD/CVD mortality:
several prospective studies (see figure)
Cardiovascular mortality in industrial workers (25,6 ys.) ys.)
2,5
2
1,5
1
0,5
*
1 2 3 1 2 3
High demand /
low control
Effort-Reward
Imbalance
Source: M. Kivimäki et al. (2002), BMJ, 325: 857
*
Tertiles
1 = low;
2 = intermediate;
3 = high
adj. for age, sex,
occupational group,
smoking, physical
activity, SBP,
total chol., BMI
* p < .05

Research strategy
Given background I-III: III: How to deal with the
association SES - work stress – CHD?
The mediation hypothesis:
hypothesis
low SES work stress CHD
The effect modification hypothesis:
hypothesis
Work stress CHD
low SES

Some evidence of effect modification of the
association between ERI and CHD by SES: SES:
Hazard ratio
highest vs. lowest ERI quartile
Whitehall II-Study II Study; ; 11 year follow-up
follow up
(N=10,308 male and female civil servants)
servants
1,8
1,6
1,4
1,2
1
0,8
All CHD
high SES medium
SES
low SES
Fatal CHD / non-fatal MI
high SES medium
SES
Source: H. Kuper et al. (2002), Occ Environment Med, 59: 777-784.
low SES

Research question
Evidence of effect modification
work stress (ERI) cardiovascular risk factors
by SES?
Heinz-Nixdorf Recall Study (HNRS)
Prospective cohort study in Western Germany
N = 4814 men/women 45-74 years
Sub sample of 1755 working persons
Baseline (2000-2003) of a 5 year-follow-up study
Cardiovascular risk factors
Prehypertension (treated hypertensives!)
Angina
Atherogenic lipids
Depressive symptoms
I. Does ERI vary with cardiovascular risk factors?
II. Does SES modify the effect of ERI on risk factors?

Measures
Socio-economic status:
Education (A-level vs. other); income (median split)
Effort-Reward Imbalance at Work: Combination of
extrinsic (ERI) and intrinsic (OC) components
1) no exposure; 2) intrinsic;
3) extrinsic; 4) combined (high risk)
Prehypertension: Omron measurement
Sys 120-139/Dia 80-89 mmHG (JNC7) [44.2 %]
Angina on exertion: Rose Questionnaire
Pain in chest and on exertion [9.9 %]
HDL Cholesterol: Serum

Results I: Association of
ERI with cardiovascular risk factors* factors
OR** 95 % CI
Prehypertension 1.39 [0.9-1.9]
Angina 2.79 [1.8-4.2]
HDL 1.44 [0.8-2.3]
Depressive symptoms 2.42 [1.7-3.3]
*) unpublished findings, findings,
please do not quote
**) both extrinsic and intrinsic vs. not exposed (reference);
Odds Ratios adjusted for age, gender, smoking, physical
exercise, BMI, (medication), seniority, working hours,
demand-control

Results II: Effect modification by SES
ERI – Angina (an example)*
example)*
OR
3,5
3
2,5
2
1,5
1
0,5
no exposure
*
intrinsic
extrinsic
*) unpublished findings, please do not quote
*
*
both
low income
high income
adjusted for age,
gender, smoking,
sport, BMI,
medication,
seniority, working
hours, demandcontrol

Study limitations
Cross-sectional results
Discussion
Inconsistent findings with regard to SES indicators
Limited validity of self-reported cv. risk factors?
Study strengths
Large representative population study with variety of
occupations (men and women)
High quality data collection (DIN ISO)
Theory-based approach (ERI model; original
measure)
Extensive confounder control

Conclusions
Part of the association SES – work stress –
CHD is elucidated by the effect modification
hypothesis
Preliminary evidence with regard to ERI and
cardiovascular risk factors
If further confirmed, findings are relevant for
preventive strategies at work: vulnerable low
SES workers as primary target group!