K2-1 Bidrar dagens arbetsliv till en ökning eller minskning av de socioekonomiska skillnaderna i hälsan / Does current working life increase or decrease socioeconomic inequalities in health Prof. Mika Kivimäki University College London, Helsingfors universitet, Arbetshälsoinstitutet University College London; University of Helsinki; Finnish Institute of Occupational Health

1. Work life and social inequalities in
health
Professor Mika Kivimaki
Department of Epidemiology & Public Health University
College London, UK
Finnish Institute of Occupational Health, Finland

2. Collaborators:
Prof. Jussi Vahtera, Drs. Marianna Virtanen, Tuula Oksanen,
Paula Salo, and Jaana Halonen, FIOH;
Prof. Sir Michael Marmot, Drs. Archana Singh-Manoux, G. David
Batty, Martin Shipley, Jane E. Ferrie, Eric Brunner, and Mark
Hamer, University College London, UK
Funding:
Academy of Finland, Finnish Work Environment Foundation, EU
New OSH ERA research programme, BUPA Foundation, British
Heart Foundation, Medical Research Council, UK, NIH, US.

3. Session Outline
The Social causation assumption (SES
health) – is it justifiable?
Understanding how work is linked with disease
risk?
Work as an explanation for social inequalities –
history and current evidence?

4. Relative inequalities in the rate of death from any cause
A real public health problem
Mackenbach et al. N Engl J Med 2008

5. 1. The social causation hypothesis SES Health
• SES determines the ability to consume goods and services – for
example, high-quality food and health care – which in turn affects health.
• Low SES is associated with higher exposure to occupational health
hazards, potentially contributing to health problems.
• Differences in social values and behavioural preferences between SES
groups may create variations in health.
2. The health-related selection hypothesis Health SES
• Childhood health is linked to educational achievement and labour
market prospects and thus to adult SES.
• Severe and limiting health problems during adulthood may increase the
risk of an income shortfall and poor career prospects.
3. The common cause hypothesis SES Health
• Common causes, such as genetic influences and personality, determine
both SES and health.
Trait

6. SES Health
Common cause: genes
Denmark, >20,000 adoptees Trait
Hazard ratio for mortality in adoptees in relation to biological and adoptive father’s social class.
Note: not replicated; specific SES-related genetic variants not identified.
Osler et al. Int J Epidemiol 2006

7. SES Health
Common cause: personality Trait
GAZEL cohort, France
BDHI, Buss-Durkee Hostility Inventory
2. 0
High
29%
1. 5
Low
RR 1. 0
0. 5
0. 0
Unadjusted Adjusted
Nabi et al. Int J Epidemiol 2008

8. SES Health
Trait
Personality in adolescence predicts education in adulthood
Young Finns, Finland
Pulkki et al. Int J Epidemiol 2003

9. Health predicting social mobility: Health SES
The Whitehall II study, the UK
Elovainio et al. Am J Epidemiol 2011

10. SES Health
Socioeconomic circumstances influence health
Elovainio et al. Am J Epidemiol 2011

11. Brief summary
The social causation SES Health
• Important at least in adulthood
The health-related selection Health SES
• Important in childhood
The common cause SES Health
• Eg. effects of personality are not trivial
Trait

12. Theoretical models on unhealthy work
To identify key elements within complex and
diverse work environments
To provide new predictions and explanations of
less well understood health/disease outcomes
To orient interventions towards healthy work and
well-being of workers
F Kittel 2010

13. Karasek 1979
Karasek & Theorell 1990
Job Strain Model

14. Job motivation and job stress
models
What I put in my work What I get from my work reward
effort
J. S. Adams: Equity Theory J. Siegrist: Effort-Reward
on job motivation 1963 Imbalance model 1996

15. Organizational justice theory
― 3 forms of justice perceptions
Distributive justice: fairness of outcomes (equity, equality, and
needs)
Procedural justice: fairness of the methods or procedures used
(decision criteria, voice, control of the process)
Relational justice: fairness of the interpersonal treatment
received (dignity and respect)
Moorman 2001, Greenberg & Cropanzano 2001, Kivimaki et al Arch Intern Med 2005

16. Organisational justice questionnaire items
Decisions…
• are well-informed,
• are consistently applied (the rules are applied equally for
everyone).
Management…
• listens to the concerns of all those affected by the decision,
• provides opportunities to appeal against or challenge the
decision,
• tries to deal with us in a truthful manner.
Kivimäki et al Psychol Med 2003

17. A quick look at evidence
1. Depression
2. CHD

18. 1. Relative risk of depression or depressive
symptoms according to job strain
Job demands
Low job control
Bonde Occup Environ Med 2008

19. Relative risk of depression or depressive
symptoms according to job strain
Job strain
Low social
support
Bonde Occup Environ Med 2008

20. Summary estimates (relative risk) for job
strain components:
1.31 (95% CI 1.08 – 1.59) for high demands
1.20 (95% CI 1.08 – 1.39) for low job control
1.44 (95% CI 1.24 – 1.68) for low social support
Bonde Occup Environ Med 2008

21. Other work stressors
Bonde Occup Environ Med 2008

22. Summary
• Both job strain and effort reward imbalance
show associations with mental health
problems, but not unanimously
• Aspects of social relations at work also related
to mental health problems
• Threat to causal inference: Reverse causation

23. An attempt to exclude the reverse causation
explanation...
Ward overcrowding - a person-independent source of work
stress for nurses
Participating hospitals routinely collect monthly figures on
bed occupancy for each ward according to a standard
procedure.
We examined a subcohort of somatic ward personnel
(n=7340) from the Public Sector Study.
Virtanen et al. Am J Psychiatry 2008

24. Overcrowding as a time-dependent
exposure (illustration)
Person A Antidepressant treatment
0 = no
0
0 1 = yes
0
0
0
0
1
Person B
0
0
0
0
0
0
0
0
0
Person C 1
0
1
6 months 8 months 10 months
Virtanen et al. Am J Psychiatry 2008

25. Virtanen et al. Am J Psychiatry 2008

26. 2. Work stress and cardiovascular disease
PART 1: Psychosocial
Psychosocial
CAUSAL MODELS factors
factors
indirect effect etiological factor trigger prognostic factor
Risk factors
Risk factors Preclinical disease
Preclinical disease Manifest disease
Manifest disease Cardiovascular
Cardiovascular
xx processes
processes xx death
death
e.g., obesity, smoking, e.g., atherosclerosis, e.g., angina, myocardial
physical inactivity, endothelic dysfunction infarction
high LDL cholesterol
confounding, bias, reversed causality
PART 2:
ALTERNATIVE
Psychosocial
Psychosocial
EXPLANATIONS
factors
factors stress
Kivimäki et al. Scand J Work Environ Health 2006

27. Underlying mechanisms
16%
16%
32%
Physical inactivity, poor diet and the metabolic syndrome the most important
explanatory factors in this cohort
Chandola et al. Eur Heart J 2008

28. Meta-analysis:
Job strain and
CVD 4/9
2/10
Kivimäki et al. Scand J
Work Environ Health
2006
Decreases risk Increases risk

29. 3-year risk of cerebrovascular disease among 48,361 women aged 18–65
years (the Finnish Public Sector Study)
Kivimäki et al. Int J Epidemiol. 2009
10-year risk of cerebrovascular disease among 49 259 women aged
30 to 50 years (The Women’s Lifestyle and Health Cohort Study, Sweden)
Kuper et al. Stroke. 2007

30. In sum, reasonable evidence to assume
social causation and to link work and
disease risk.
But are work characteristics linked with
social inequalities in health?

31. Marmot et al. Lancet 1997

32. ”CONCLUSION: Much of the inverse social gradient in incident CHD can be attributed to
differences in psychosocial work environment…” P. 235.
Thompson ISI web of science: 519 citations in 17/08/2011
Marmot et al. Lancet 1997

33. Marmot et al. Diabetologia 2008
“…psychological distress explained only 2% of the association between SES and all-cause
mortality when assessed at baseline (hazard ratio for mortality changed from 1.60; 95% CI
1.26-2.04, to 1.58; 95% CI, 1.24-2.02) and 5% when assessed longitudinally (adjusted hazard
ratio, 1.56; 95% CI, 1.23-1.99).”
Stringhini et al. JAMA 2010

34. A contemporary cohort of 48,000 employed women, 3.5-y follow-up
The Finnish Public Sector Study
Kivimaki et al. Int J Epidemiol 2009

35. The Danish Work Environment Cohort Study
(DWECS)
Relative risk (95% CI) for SES and sickness absence
MEN WOMEN
Adjusted for age and family status
1.37 (1.21 to 1.55) 1.30 (1.14 to 1.47)
+ health behaviours
1.33 (1.17 to 1.51) (3%) 1.24 (1.09 to 1.41) (5%)
+ physical work environment
1.10 (0.95 to 1.28) (20%) 1.14 (0.99 to 1.32) (12%)
+ psychosocial work environment
1.09 (0.93 to 1.29) (20%) 1.09 (0.93 to 1.28) (16%)
Christensen et al. J Epidemiol Community Health 2008