Is the effect of work stress on cardiovascular mortality confounded by socioeconomic factors in the Valmet study?
- E J Bruner1,
- M Kivimäki2,
- J Siegrist3,
- T Theorell4,
- R Luukkonen5,
- H Riihimäki5,
- J Vahtera6,
- J Kirjonen7,
- P Leino-Arjas5
- 1International Centre for Health and Society, Department of Epidemiology and Public Health, University College London, UK
- 2Department of Psychology, University of Helsinki, Helsinki, Finland
- 3Department of Medical Sociology, University of Duesseldorf, Duesseldorf, Germany
- 4Department of Public Health Sciences, Karolinska Institutet and National Institute for Psychosocial Factors and Health, Stockholm, Sweden
- 5Department of Epidemiology and Biostatistics, Finnish Institute of Occupational Health, Helsinki, Finland
- 6Turku Regional Institute of Occupational Health, Turku, Finland
- 7University of Jyväskylä, Finland
- Correspondence to: Dr E J Brunner International Centre for Health and Society, Department of Epidemiology and Public Health, University College London, 1–19 Torrington Place, London WC1E 6BT, UK; e.brunnerucl.ac.uk
- Accepted 22 March 2004
The link between work stress and cardiovascular disease (CVD) is robust, but derived exclusively from observational studies.1 The work stress effect may thus not be causal, but attributable to confounding with low socioeconomic position.2 This report examines the confounding explanation for the effects of work stress on CVD mortality in the Valmet study,3 using measures of socioeconomic circumstances across the life course.
PARTICIPANTS, METHODS, AND RESULTS
Participants were staff at a metal working company in Finland. The baseline survey (1973) identified those who were free from CVD at baseline (812 employees: 545 men, 267 women) and determined stressful characteristics of work and socioeconomic factors. The questionnaire based evaluation of work stress has been described in detail.3 Principal component analysis was used to derive internally consistent scales from existing questionnaire items on work demands, job control, effort at work, and material and psychosocial rewards. Content validity was high compared with the current instruments. Missing values for father’s occupation (n = 14) and participant’s salary (n = 40) were imputed (SAS proc mi and proc mianalyze) in relevant analyses using five imputations based on maximum likelihood estimates. The outcome was cardiovascular mortality 1973–2000 from the national mortality register. …
