Association of lifelong occupation and educational level with subclinical atherosclerosis in different European regions : Results from the IMPROVE study

BACKGROUND AND AIMS: We aimed to examine the association between socioeconomic status (SES) and subclinical atherosclerosis, as assessed by carotid intima-media-thickness (C-IMT) and to investigate whether the effect of social inequality on C-IMT is mediated by cardiovascular (CV) risk factors and whether it is dissimilar in men and women, and in different European countries. METHODS: We assessed the association of lifelong occupation and educational level with C-IMT in the IMPROVE study cohort including 3703 subjects (median age 64.4 years; 48% men) from Southern (Italy), Western (France and the Netherlands) and Northern Europe (Finland and Sweden). Three summary measures of C-IMT (IMTmean, IMTmax, IMTmean-max), obtained from four segments of both carotids, were considered. RESULTS: After adjusting for conventional CV risk factors, current employment status and diet, C-IMT was higher in manual workers than in white collars (+7.7%, +5.3%, +4.6% for IMTmax, IMTmean-max and IMTmean, respectively; all p<.0001). Similar results were obtained by stratification for educational level. The effect of occupation on C-IMT was comparable in men and women and in different age groups, and was only partially mediated by differences in CV risk factors. Of note, the association of C-IMT with occupation was significant in Western and Northern Europe but not in Italy, with a significant statistical interaction (p = .0005). CONCLUSIONS: Low SES was associated with subclinical atherosclerosis in subjects with at least three CV risk factors. Such association was stronger in Northern and Western Europe than in Italy. This difference was not completely explained by inequalities in CV risk factors and behavioural variables.