Work life and social inequalities in

healthhealth

Professor Mika Kivimaki

Department of Epidemiology & Public Health University

College London, UK

Finnish Institute of Occupational Health, Finland

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.

Session Outline

� The Social causation assumption (SES health) – is it justifiable?

� Understanding how work is linked with disease � Understanding how work is linked with disease risk?

� Work as an explanation for social inequalities –history and current evidence?

Relative inequalities in the rate of death from any cause

A real public health problem

Mackenbach et al. N Engl J Med 2008

1. The social causation hypothesis

• 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

SES Health

SESHealth2. The health-related selection hypothesis

• 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

• Common causes, such as genetic influences and personality, determine

both SES and health.

SESHealth

SES Health

Trait

Common cause: genes

Denmark, >20,000 adoptees

Hazard ratio for mortality in adoptees in relation to biological and adoptive father’s social class.

SES Health

Trait

Osler et al. Int J Epidemiol 2006

Note: not replicated; specific SES-related genetic variants not identified.

Common cause: personality

GAZEL cohort, France

SES Health

Trait

BDHI, Buss-Durkee Hostility Inventory

Nabi et al. Int J Epidemiol 20080 . 0

0 . 5

1 . 0

1 . 5

2 . 0

Unadjusted Adjusted

High

Low

29%

RR

Personality in adolescence predicts education in adulthood

Young Finns, Finland

SES Health

Trait

Pulkki et al. Int J Epidemiol 2003

Health predicting social mobility:

The Whitehall II study, the UK

SESHealth

Elovainio et al. Am J Epidemiol 2011

Socioeconomic circumstances influence health

SES Health

Elovainio et al. Am J Epidemiol 2011

The social causation

• Important at least in adulthood

The health-related selection

SES Health

SESHealth

Brief summary

• Important in childhood

The common cause

• Eg. effects of personality are not trivial

SES Health

Trait

Theoretical models on unhealthy work

� To identify key elements within complex and

diverse work environmentsdiverse 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

Karasek 1979

Karasek & Theorell 1990

Job Strain Model

Job motivation and job stress

models

rewardWhat I put in my work What I get from my work

J. S. Adams: Equity Theory

on job motivation 1963

effort

J. Siegrist: Effort-Reward

Imbalance model 1996

What I put in my work What I get from my work

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 � 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

Organisational justice questionnaire items

Decisions…• are well-informed,

• are consistently applied (the rules are applied equally for

everyone).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

A quick look at evidence

1. Depression1. Depression

2. CHD

Relative risk of depression or depressive

symptoms according to job strain

Job demands

1.

Bonde Occup Environ Med 2008

Low job control

Relative risk of depression or depressive

symptoms according to job strain

Job strain

Bonde Occup Environ Med 2008

Low social

support

Summary estimates (relative risk) for job

strain components:

1.31 (95% CI 1.08 – 1.59) for high demands

Bonde Occup Environ Med 2008

1.20 (95% CI 1.08 – 1.39) for low job control

1.44 (95% CI 1.24 – 1.68) for low social support

Other work stressors

Bonde Occup Environ Med 2008

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

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.procedure.

We examined a subcohort of somatic ward personnel

(n=7340) from the Public Sector Study.

Virtanen et al. Am J Psychiatry 2008

Overcrowding as a time-dependent

exposure (illustration)

00

0

1

0

0

0

Antidepressant treatment

0 = no

1 = yes

0

Person A

Person B

Virtanen et al. Am J Psychiatry 2008

00

0

1

0

0

0

00

0

01

6 months 8 months 10 months

Person C

Virtanen et al. Am J Psychiatry 2008

PART 1:CAUSAL MODELS

Risk factors Preclinical disease CardiovascularManifest disease

Psychosocialfactors

indirect effect prognostic factoretiological factor trigger

Risk factors Preclinical disease Manifest disease Cardiovascular

Psychosocialfactors

2. Work stress and cardiovascular disease

Risk factorsx

Preclinical diseaseprocesses

Cardiovasculardeath

Manifest diseasex

e.g., obesity, smoking,

physical inactivity,

high LDL cholesterol

e.g., atherosclerosis,

endothelic dysfunction

e.g., angina, myocardial

infarction

PART 2:ALTERNATIVEEXPLANATIONS Psychosocial

factors stress

confounding, bias, reversed causality

Risk factorsx

Preclinical diseaseprocesses

Manifest diseasex

Cardiovasculardeath

Psychosocial

factors

Kivimäki et al. Scand J Work Environ Health 2006

Underlying mechanisms

16%

16%

32%

Physical inactivity, poor diet and the metabolic syndrome the most important

explanatory factors in this cohortChandola et al. Eur Heart J 2008

Meta-analysis:

Job strain and

CVD 4/9

Kivimäki et al. Scand J

Work Environ Health

2006Decreases risk Increases risk

2/10

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. 2009Kivimäki 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

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?

Marmot et al. Lancet 1997

”CONCLUSION: Much of the inverse social gradient in incident CHD can be attributed to

differences in psychosocial work environment…” P. 235.

Marmot et al. Lancet 1997

Thompson ISI web of science: 519 citations in 17/08/2011

“…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

Marmot et al. Diabetologia 2008

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

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)

The Danish Work Environment Cohort Study

(DWECS)

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