Epidemiology: Open Access
Open Access

Abstract

Social inequalities constitute a relevant topic in the epidemiology literature. Recent research questioned whether social position interacts with risk factors, exacerbating their unfavourable effects, under a â�?�?differential vulnerabilityâ�? mechanism When measured on an additive scale such as the absolute risk of event, the interaction between social class and risk factors provides valuable information on which subgroups in the population may benefit most by preventive strategies. However, this important mechanism has been under-investigated so far, as large prospective studies are needed to provide precise interaction estimates. We tested the differential vulnerability hypothesis in incident coronary heart disease and stroke using data from 11 populations in 9 European countries, all participating in the MORGAM collaborative project, with harmonized baseline and follow-up data. Overall, 77 918 men and women with 9334 incident events occurring during a median follow-up of 12 years. We found evidence that low education exacerbates the effect of cardiovascular disease risk factors on the absolute risk of coronary heart disease or stroke between the ages of 35 and 75, in individuals initially free of CVD. In men, this synergistic interaction was mainly driven by smoking; in women by clustering of smoking, elevated blood pressure and obesity. Standard survival analysis, ignoring competing risks, led to over-estimating the interaction between low education and risk factors, in particular smoking and body mass index. Our study calls for future research pursuing explanations for the differential vulnerability we demonstrated, such as the accumulation of psychosocial stressors and allostatic load among the socially disadvantaged over lifetime.

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