Interplay of education and income in cardiovascular disease risk in US adults

Income and education play an important role in the health and well-being of individuals. In the US, there is a disparity in health outcomes among people of differing socio-economic status. The uneven distribution of one such condition that is of public health concern is cardiovascular disease (CVD).

CVD, which encompasses congestive heart failure (CHF), angina, heart attack and stroke, contributes significantly to annual mortality and morbidity in the US. Stroke is one of the most common CVD conditions and GlobalData estimates that in the US, by the end of 2025, there will be more than 430,000 incident cases of acute ischaemic stroke (arterial ischaemic stroke and transient ischaemic stroke combined) in adult men and women aged 18 and older. That number has been forecast to increase to 450,000 incident cases by the end of 2027.

The gap in CVD outcomes in the US is largest between the top 20% of earners and the rest of the population. Key markers of good health resources and practices that co-vary with income, such as education level, play a role in likelihood of developing CVD and thus its prevalence.

Salma Abdalle and colleagues centred their research question on this and conducted a study to describe how stratifications of population by income and education explain the gap and patterns in CVD outcomes between 1999 and 2018. The study was published in The Lancet Regional Health-Americas using data from a representative sample of 49,704 American adults from the National Health and Nutrition Examination Survey (NHANES).

A small group experiences a greater abundance of protective factors

Education is closely associated with income, which is associated with health outcomes; this relationship dynamic is reflected in the findings of the study where researchers saw that 55.8% of the top 20% of earners in the US were college graduates compared to 18.7% of bottom 80%. The reported prevalence of CHF in the top 20% of earners with a college degree was 0.5%. This reported prevalence increased to 1.5% of the top 20% of earners without a college degree, 1.6% of the bottom 80% of earners with a college degree and finally 3% of the bottom 80% of earners without a college degree. The same pattern of decreasing prevalence by socio-economic subgroup was witnessed for angina.

The prevalence of heart attacks showed an unconventional pattern: 1.7% for the top 20% of earners with college degrees, followed by 2.1% in the bottom 80% of earners with a college degree, then 3.2% for the top 20% of earners without a college degree, and finally the bottom 80% of earners without a college degree experiencing the highest prevalence at 3.9%. Stroke prevalence displayed a similar pattern, except the lowest prevalence rates remained constrained to the top 20% of earners, and the bottom 80% of earners with and without a college degree experienced the highest prevalence.

The bottom 80% of earners with no college degree were at greater odds of experiencing CHF, angina or stroke compared to their counterparts in the top 20% of earners bracket with a college degree. The bottom 80% of earners with a college degree were at greater odds of experiencing CHF or a stroke. Interestingly, the top 20% of earners without a college degree had greater odds of experiencing a heart attack or stroke.

Important conclusions can be drawn from this study. One is that a small group of Americans experience a greater abundance of protective factors reducing their CVD risk. Another is that an accumulation of several favourable resources determines CVD health outcomes better than any individual factor or single socio-economic indicator.