Lifestyle factors, including weight, blood pressure and smoking, explain around 40% of the protective effect of education on heart disease risk in later life, suggests a study* published by The BMJ today.
Results suggest that intervening on these “modifiable” risk factors could lead to reductions in cases of heart disease as a result of lower educational achievement.
However, the researchers also say that more than half of this protective effect still remains unexplained and needs to be investigated.
It is well established that lower levels of education are related to higher cardiovascular risk in later life, but educational opportunities are different across the population, so the key to improving heart health in later life could lie in tackling the risk factors that drive these poorer outcomes.
To test this theory, an international team of researchers set out to investigate the role of body mass index (BMI), systolic blood pressure and smoking in explaining the protective effect of education on cardiovascular risk.
They carried out observational and genetic analysis of data from 217,013 adults in the UK Biobank - a large population based study of more than half a million British men and women – in addition to a two-sample Mendelian randomisation approach from predominantly European studies.
This technique uses genetic information to avoid some of the problems that affect observational studies, making the results less prone to unmeasured (confounding) factors, and therefore more likely to be reliable in understanding cause and effect.
In both observational and Mendelian randomisation analyses, the researchers found consistent evidence that BMI, blood pressure and smoking mediated the effect of education, explaining up to 18%, 27% and 34% respectively.
When all three risk factors were combined, they explained around 40% of the relationship between education and cardiovascular disease. Similar results were found for risk of stroke, heart attack, and all other types of cardiovascular disease.
Therefore, the researchers suggested that intervening on these risk factors “would lead to reductions in cardiovascular disease attributable to lower levels of education.”
However, they added that it was important to note that over half of the overall effect of education remained unexplained.
They acknowledged some study limitations, such as the main analysis not considering factors such as exercise, diet, cholesterol and blood sugar levels, and as participants were mostly white Europeans, findings may not be applicable to other populations.
Nevertheless, they stress that results were consistent across the two approaches and in additional sensitivity analyses, suggesting that the findings were robust.
“The findings of this study have notable implications for policymakers as they identify potential strategies for reducing education inequalities in health,” they concluded.
Further research identifying other related factors and the interplay between them - and in more diverse populations – would be important to reduce inequalities in cardiovascular disease.
*Carter A R, Gill D, Davies N M, et al. Understanding the consequences of education inequality on cardiovascular disease: mendelian randomisation study. BMJ 2019;365:l1855. DOI: 10.1136/bmj.l1855