Background: Numerous studies have demonstrated social inequalities in coronary heart disease using a variety of measures of social position. In this study we examine associations between persistent economic difficulties and serious coronary events. Our aim is to assess whether these associations are (i) explained by other measures of socioeconomic status, and (ii) mediated by psychosocial, behavioural and biological factors.
Methods: The data come from 5021 middle-aged, white-collar men in the Whitehall II study. Self-reported household financial problems, measured at baseline (1985-88) and Phase 3 (1991-93), were used to construct a five-category score of persistent economic difficulties. Associations between economic difficulties and incident coronary events were determined over an average follow-up of 7 years. Other socioeconomic, psychosocial, behavioural and biological explanatory variables were obtained from the Phase 3 questionnaire and clinical examination.
Results: Age-adjusted Cox regression analyses demonstrated steep gradients in the incidence of coronary events with economic difficulties. The relative hazard between the bottom and the top of the difficulties hierarchy was 2.5 (95% confidence intervals (CI) 1.2-5.2) for fatal and non-fatal myocardial infarction (MI), 2.1 (1.3-3.6) for MI plus definite angina and 2.8 (1.9-4.2) for total coronary events. Adjustment for other markers of socioeconomic position, early life factors, psychosocial work environment characteristics and health-related behaviours had little effect, while adjustment for the biological factors reduced the association between difficulties and coronary events by 16-24%.
Conclusion: We have demonstrated an economic difficulties gradient in coronary events in men that is independent of other markers of socioeconomic position and appears to be only partially mediated by well-known risk factors in mid-life.