Longer education may lower risk of coronary heart disease
Low education tends to increase the risk of developing coronary heart disease (CHD), and the potential mechanisms include smoking, blood lipids and body mass index (BMI), according to a recent study.
“Our Mendelian randomization analyses found genetic support for the hypothesis that longer education plays a causal role in lowering the risk of coronary heart disease,” researchers said. “Although completely ruling out possible pleiotropic effects is difficult, the sensitivity tests available to us gave little evidence that these could have driven our findings.”
Genetic predisposition towards 3.6 years of additional education appears to result in about one-third decrease in the risk of CHD (odds ratio [OR], 0.67; 95 percent CI, 0.59 to 0.77; p=3x10-8). This was similar to findings from several traditional observational studies (prevalence OR, 0.73; 0.68 to 0.78; incidence OR, 0.80; 0.76 to 0.83). [BMJ 2017;358:j3542]
A causal interpretation, in which major bias from genetic pleiotropy was unlikely, was consistent with sensitivity analyses. However, possibility remains untestable. In addition, genetic predisposition towards longer education correlated with less smoking, lower BMI and a favourable blood lipid profile.
“Our findings using genetic data, which can be considered as ‘nature’s randomized trials’, were consistent with data from observational studies, and we found little evidence that our results may be driven by genetic pleiotropy,” researchers said. [Lancet 2005;358:1906-8]
“More specifically, 3.6 years of additional education—similar to an undergraduate university degree—is predicted to translate into about a one-third reduction in the risk of CHD,” they added.
The association between education and CHD has been observed in a vast body of studies across a range of settings, but comparatively few studies have openly examined the causality of this association. [J Hum Resour 2009;358:1-33; Rev Econ Stud 2005;358:189-221; Econ Perspect 2008;358:2-16; Proc Natl Acad Sci U S A 2012;358:8461-6]
While the mechanisms that mediate the association between education and CHD remain relatively unknown, the current study found genetic predisposition towards longer education to associate with improved smoking, BMI and blood lipid profiles, with some borderline results for blood pressure and risk of diabetes.
“The degree of mediation should now be formally assessed with more extensive methods—for example, by applying two-step Mendelian randomization,” researchers said. [Circ Res 2015;358:665-73; J Law Econ 2013;358:959-96]
“If conventional risk factors do not completely account for the mechanism between education and CHD, then additional mechanistic hypotheses for investigations are needed,” they added.
Such hypotheses could include education leading to improved use of healthcare services (from better health knowledge or fewer financial barriers to accessing care) or better job prospects, income, material conditions, social ranking and/or diet, all factors associated with education and CHD, many of which might be amenable to intervention. [J Epidemiol Community Health 1998;358:153-60]
In this study, researchers obtained genetic data from two large consortia, CARDIoGRAMplusC4D and SSGAC, comprising 112 studies from predominantly high-income countries (n=543,733 participants). The findings were then compared against results from traditional observational studies (n=164,170 participants). Finally, genetic data from six additional consortia were analysed to determine whether longer education can causally change the common cardiovascular risk factors.
“In conjunction with the results from other study designs, increasing education is likely to lead to health benefits,” researchers concluded.