Workplace socioeconomic characteristics and coronary heart disease: a nationwide follow-up study

OBJECTIVES: Important gaps in previous research include a lack of studies on the association between socioeconomic characteristics of the workplace and coronary heart disease (CHD). We aimed to examine two contextual factors in association with individuals’ risk of CHD: the mean educational level of all employees at each individual’s workplace (education(work)) and the neighbourhood socioeconomic characteristics of each individual’s workplace (neighbourhood SES(work)). DESIGN: Nationwide follow-up/cohort study. SETTING: Nationwide data from Sweden. PARTICIPANTS: All individuals born in Sweden from 1943 to 1957 were included (n=1 547 818). We excluded individuals with a CHD diagnosis prior to 2008 (n=67 619), individuals without workplace information (n=576 663), individuals lacking residential address (n=4139) and individuals who had unknown parents (n=7076). A total of 892 321 individuals were thus included in the study (426 440 men and 465 881 women). PRIMARY AND SECONDARY OUTCOME MEASURES: The outcome variable was incident CHD during follow-up between 2008 and 2012. The association between education(work) and neighbourhood SES(work) and the outcome was explored using multilevel and cross-classified logistic regression models to determine ORs and 95% CIs, with individuals nested within workplaces and neighbourhoods. All models were conducted in both men and women and were adjusted for age, income, marital status, educational attainment and neighbourhood SES(residence). RESULTS: Low (vs high) education(work) was significantly associated with increased CHD incidence for both men (OR 1.29, 95% CI 1.23 to 1.34) and women (OR 1.38, 95% CI 1.29 to 1.47) and remained significant after adjusting for potential confounders. These findings were not replicable for the variable neighbourhood SES(work). CONCLUSIONS: Workplace socioeconomic characteristics, that is, the educational attainment of an individual’s colleagues, may influence CHD risk, which represents new knowledge relevant to occupational health management at workplaces.