Is the effect of work stress on cardiovascular mortality confounded by socioeconomic factors in the Valmet study?

Abstract
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.