Objectives: To investigate the association of socio-economic status, defined by occupational class, income and education, with coronary heart disease (CHD) morbidity and mortality, and further to analyse to which extent modifiable risk factors may explain socio-economic differences in CHD risk.
Design: A population-based prospective cohort study including 9,061 men and 10,211 women aged 35-64 at baseline who participated in a cardiovascular risk factor survey in 1982, 1987, 1992 or 1997 in Finland. The subjects were followed for CHD events up till the end of 2001. Cox's proportional hazards model was used in the analysis.
Results: Male manual workers had a double risk of CHD death compared with upper-level employees (HR=2.00, 95% CI 1.35-2.97). This excess risk was reduced by 31% when adjusted for traditional cardiovascular risk factors and most of this reduction was due to smoking.
Conclusions: Modifiable risk factors explained about a third of the excess CHD mortality between manual workers and upper-level employees in men. Among women the differences between socio-economic groups were not statistically significant.