Social 
 Determinants 
 of Health 

How the Social Determinants of Health Relate to Cardiovascular Health

On this page, I'll take you through the relationship between two variables: the Social Determinants of Health (SDoH) and Cardiovascular Health, as defined by the American Heart Association's Life's Essential 8 (LE8).

Social Determinants of Health

You can click the image above to get one of the official definitions of SDoH, and/or read how I define it here. The SDoH are factors that affect health, but aren't directly related to health. For example, neighborhood safety--not directly related to health, but it affects whether you can exercise outside or not, which means it affects health. 

Some people think of negative factors as SDoH, like poverty, racism, poor education, etc. While important, these are social determinants of disease, not health. On this page, we will focus on factors that positively affect health--positive SDoH--though the flip side is their absence negatively affects health. I will be using the following variables:

Life's Essential 8

Click the image above for more information on LE8. It is a score made up of 8 factors that are associated with good heart health.

The first four are called health factors, and the last four are called health behaviors. 

Each factor or behavior is scored from 0 to 100 (higher is better), and a composite score is created from an average of all the individual scores. We will be looking at how the SDoH are associated with both the individual scores and the composite scores.

The Data

The data come from the National Health and Nutrition Examination Survey (NHANES). They are weighted to represent the United States' population. Basically, these numbers are an accurate representation of Americans. 

One thing I wish were included in NHANES is some measure of racism or discrimination. This is an important factor that affects health that I cannot analyze with these data.

Methods

I used weighted linear models that accounted for the complex survey design of NHANES. The analysis was done in the R programming language with the "survey" package, created by Thomas Lumley.

The models were adjusted for (median-centered) age and sex. This means the results can be thought of as if everyone is the median age and the same sex. I did not adjust for race or ethnicity, because I would only get results relevant to whichever race was the reference category. Instead, I broke the data down by race and analyzed each race separately.

Results

First, we'll look at the association between the SDoH and the composite LE8 score. Brace yourself; there's a lot going on in this next graph. Don't worry; I'll take you through it.

What you see in this figure is the increase in cardiovascular health (increase in LE8 score) that accompanies each SDoH. For example, home ownership is associated with an approximate 2.5-point to 5-point higher LE8 score over people who rent their homes. Earning the median income or higher is associated with about 5 points gained in Asian, Black, and Hispanic Americans, and 10 points gained in White Americans (when you compare them to members of the same race who are paid less than the median income).

For 4 of the 5 SDoH variables, White Americans seem to gain more cardiovascular health points than the other groups. This may be explained in part by racism, which is not measured in NHANES. This concept is referred to as "diminishing returns," i.e. people of color achieve the same level of income, education, etc. as their White peers, but don't see the same benefits that usually go along with those achievements. Read more about this here.

The good news is, everyone's health is better with positive SDoH. But why? What, specifically, is better with college education? Which of the health factors? Which of the health behaviors? What is driving the increase in LE8 score?

The answers to these questions are below, broken down by race or ethnicity. We'll go alphabetically through the list of racial/ethnic groups.

What we're looking for, here, is health factors and health behaviors where the change in LE8 score doesn't touch the dashed zero line and isn't negative. For example, home ownership is associated with better physical activity among Asian Americans. In fact, all of the SDoH except employment are associated with better physical activity. My favorite, diet, has higher scores when people are making more money, food secure, and college educated. From this graph, it looks like diet and physical activity are driving the higher LE8 scores among Asian Americans with positive SDoH.

Let's see if this holds true in the next group, Black Americans.

Well hello smoking! It appears positive SDoH is associated with better smoking habits (i.e. not doing it) among Black Americans. Diet and physical activity are generally better as well. It's looking like positive SDoH is associated with better health behaviors more so than better health factors.

Next, let's look at these associations among Hispanic Americans.

Here we see more of the same in regards to health behaviors influencing the higher LE8 scores with positive SDoH. Physical activity and smoking are the main ones, here.

Last, but not least, White Americans.

Here, we see why scores were so much higher with positive SDoH in the first graph I showed. There's a big difference in smoking and physical activity with positive SDoH among White Americans. Diet and sleep also demonstrate respectable differences. Even a few of the health factors show better scores with some SDoH variables. Positive SDoH is associated with some distinct health benefits among White Americans.

It is well known that minority groups in the United States (especially Black and Hispanic groups) are less healthy than the majority group. They get sick at higher rates, they get sick earlier in life, and they're more likely to die from these sicknesses than the majority group. One theory is that closing the gaps in SDoH will fix these issues. What I've shown here is that closing SDoH gaps will definitely be an improvement, but due to diminishing returns, minority groups may not achieve equitable health outcomes with improved SDoH alone. We will all need to work together to come up with equitable solutions to end health disparities in this country.

As always, thanks for reading!