Education and Coronary Heart Disease Risk Associations May be Affected by Early-Life Common Prior Causes: A Propensity Matching Analysis

PURPOSE: Education is inversely associated with coronary heart disease (CHD); however whether this is attributable to causal effects of schooling rather than potential confounders existing before school entry (eg, childhood intelligence, childhood economic circumstances, childhood chronic illness, parental mental health) remains unknown. We evaluated whether education is associated with 10-year CHD risk independent of 21 prospectively assessed childhood conditions, in participants ages 38-47 years. METHODS: Using linear regression analyses, we evaluated associations of education with 10-year CL-ID risk, the latter calculated by use of the validated Framingham risk algorithm incorporating diabetes, blood pressure, total and high-density lipoprotein cholesterol, smoking, age, and sex. Propensity score matching incorporated 21 early-life potential confounders. RESULTS: Regression analyses demonstrated college graduation was associated with -27.9% lower (95% CI, -36.2, -18.6%) 10-year CHD risk compared with <= high school after matching on propensity score that included age, sex and race (n = 272); addition of 21 early life potential confounders resulted in effect size of -13.1% (95% CI, -33.4, 13.4; mean n = 110). CONCLUSIONS: Participants with college degree had substantially lower risk of CHD (27.9%) after accounting for demographics; the addition of early life potential confounders resulted in a moderate effect size (13.1%), suggesting potential importance of early life factors in explaining observed associations between education and CHD risk. Ann Epidemiol 2012;22:221-232. (C) 2012 Elsevier Inc. All rights reserved.