4 studies that defy conventional thinking about race, weight loss, and heart health
February 3, 2021
In the last 15 to 20 years, we've made leaps and bounds in measuring modifiable and nonmodifiable risk factors for conditions such as cancer, diabetes, and heart disease.
However, racial disparities in the burden of heart disease and associated adverse outcomes have persisted in our society, with Black people being disproportionately affected compared with other groups. It is important to gain a better understanding of the underlying drivers of these diseases to improve the associated outcomes across all sectors of society.
Lifestyle factors such as diet, exercise, and obesity represent some of the modifiable risk factors, whereas genetic markers associated with certain medical conditions represent nonmodifiable risk factors that underlie disease development and progression.
We must gain a better understanding of how healthy behaviors, when combined with better access to care, can modify the risk of adverse outcomes associated with such conditions to improve the overall cardiovascular health of our society.
At UT Southwestern, we recently completed a series of studies that delved deeper into the data. The results upended some preconceived notions about heart care. For example:
- Social factors, rather than genetics, drive racial differences in blood pressure control
- Not all weight loss is equally effective when it comes to improving heart health.
- Cardiovascular care can be improved when access to care is increased.
- An aspirin a day isn’t the correct recommendation for all patients with heart disease.
Our studies quantify certain risk factors that patients can and cannot change. The data highlight the significant role that social constructs such as racial bias, environmental factors, and access to health care play in our health – and they lay the groundwork to create strategies that can help eliminate some longstanding health care disparities.
1. African ancestry is not a risk factor for poor blood pressure control
Many patients and some providers assume that African ancestry is itself a risk factor for hypertension, and that the higher the degree of African ancestry, the higher the risk. Our study disproves this assumption.
Shreya Rao, M.D., a cardiology fellow at UT Southwestern, led a team that analyzed data from the Systolic Blood Pressure Intervention Trial (SPRINT) – a 2010 to 2015 multicenter study of the safety and efficacy of intensive lowering of systolic blood pressure, which is the top number in a patient's blood pressure reading.
SPRINT included 9,361 patients who self-identified their race and ethnicity. Each patient received similar access to doctors and medications, and each received a care plan to help them achieve a healthy systolic blood pressure of 120 mm/Hg or 140 mm/Hg.
From May to September 2020, we reviewed data from 2,466 participants (45.5 percent women) who self-identified as Black with available West African ancestry proportion based on 106 genetic markers. The genetic markers made it possible to measure potential links between ancestry and poor blood pressure control or the occurrence of heart and kidney diseases over the four years that patients were followed.
Our study found that having West African ancestry is not itself a risk factor for inadequate blood pressure control. Black patients needed an average of 2.5 medications to achieve their goal number regardless of their amount of West African ancestry, and there was no difference in the time it took to achieve blood pressure control among patients with different levels of West African ancestry. In fact, individuals with a higher degree of West African ancestry had a slightly lower risk of adverse cardiac events, such as heart attack or heart failure.
By demonstrating that genetics did not play a large role in determining Black patients’ blood pressure outcomes, our findings suggest that societal factors such as access to education, healthy food, and adequate health care are major factors driving the increased rates of hypertension and cardiovascular disease among Black patients.
2. For heart health, not all weight loss is equal.
Nearly 33 million people in the U.S. today have type 2 diabetes, and approximately 655,000 people in the U.S. die of heart disease each year. Being overweight or obese is a major risk factor for both conditions. Belly fat may contribute to heart risks by increasing inflammation, interfering with hormone levels, and fueling abnormal cell growth.
This type of fat can surround internal organs and lead to greater risk of developing health problems.
Providers often make a general recommendation that patients should lose weight to improve their heart health. Whereas overall weight loss can be beneficial, our recent study found that not all weight loss is equally effective when it comes to improving heart health.
We found that losing fat, specifically central/belly fat, rather than lean muscle lowers the risk of heart failure in patients with diabetes. And personalized recommendations are key – not everyone will benefit in the same way from the blanket advice to "lose weight and move more."
We analyzed data from the Look AHEAD (Action for Health in Diabetes) Trial, which studied how weight loss, exercise, and diabetes education affected heart failure outcomes over 12 years for more than 5,000 overweight or obese adults with type 2 diabetes.
We validated a well-established and simple equation to calculate body composition, lean mass, and fat mass among the participants in the Look AHEAD trial in the subset who had a dual-energy X-ray absorptiometry (DEXA) machine to determine body composition. The DEXA is a precise but expensive piece of body scanning equipment not available in all physician offices. Our equation incorporates a patient's age, sex, race, ethnicity, height, weight, and waist circumference.
Our analysis showed that reducing fat mass and waist circumference dramatically reduced patients' heart failure risk. A 10 percent reduction in fat mass resulted in an almost 25 percent lower risk of heart failure. For example, if you reduce your waistline from 40 inches to 36 inches, you can cut your risk by a quarter.
Waist circumference reductions significantly lowered the risk of heart failure with preserved ejection fraction, a type of heart failure in which the heart muscle does not relax properly and for which there are no effective therapies.
However, reducing lean mass did not affect heart failure risk. This may be because muscle tissue helps regulate insulin sensitivity, which helps your body absorb nutrients. Losing muscle tissue may also cause your body to turn nutrients into fat cells instead of muscle cells.
In other words, the general recommendation to "lose weight" may not be specific enough to help a patient modify their heart failure risk. Instead, patients should work with their doctors to personalize a nutrition and exercise plan that targets belly fat.
Doing resistance exercises and cardio workouts such as walking or running can help burn belly fat and build lean muscle. Consuming drinks and foods that are low in added sugars and eating plenty of leafy greens, fiber, lean proteins, and healthy fats can also help trim your waistline.
3. Medicaid expansion improves cardiovascular care
Use of preventive cardiovascular therapies such as statins and blood pressure-lowering agents are known to improve outcomes in older adults. However, lack of insurance has been a key challenge in access to these therapies among socioeconomically disadvantaged individuals.
We wanted to find out whether expanding access to affordable coverage under programs such as Medicaid would increase the use of these therapies across a wider population. Our study analyzed national and state Medicaid data from 2011 to 2018 to compare prescription claims and costs between states that did and did not expand Medicaid by January 2014.
We found that expansion states had greater uptake of prescriptions for statins and blood pressure-lowering medications than nonexpansion states. From 2013 to 2018, expansion states saw an increase of more than 75 percent for both statins and antihypertensives, whereas nonexpansion states saw a 44 percent decline in prescriptions.
Previous research has shown that Medicaid expansion states saw improved mortality rates and reduced cardiovascular deaths. Our study findings suggest that greater access to effective cardiovascular drugs may be one of the potential mechanisms through which Medicaid expansion may have contributed to improvement in cardiovascular death rates.
4. Not all patients benefit from aspirin therapy to prevent heart attacks
Although aspirin has been prescribed for heart attack prevention for decades, it is also known to increase the risk of bleeding in some patients. New guidelines from the American Heart Association and American College of Cardiology suggest a more nuanced recommendation, specifically for those with the highest risk of cardiac events. However, the path to determine which patients could benefit most has been unclear.
We know that having a high coronary artery calcium (CAC) score – the level of calcium deposits in the arteries – identifies patients most at risk for atherosclerotic heart disease, also known as hardening of the arteries. Our colleague, Amit Khera, M.D., led a study to determine whether CAC can also indicate who might benefit most from aspirin therapy.
Dr. Khera and his team analyzed data from 2,191 Dallas Heart Study patients, 47 percent of whom were Black and 57 percent of whom were women. Patients' CAC scores were categorized at 0-99 and 100 or more, from least to most calcium deposits.
The data showed that patients with a CAC score of 100 or higher had a 15-times greater risk of atherosclerotic heart disease and threefold risk of bleeding compared with patients with a CAC score of 0. In other words, this study showed that having a high CAC score can be a sign that aspirin therapy may be beneficial, but only if the patient has a low bleeding risk.
The data reinforce that aspirin should not be a one-size-fits-all therapy and confirm that CAC scanning can help doctors and patients make more tailored decisions around its use.
Data and discovery can drive more equitable care
Improving patients' health requires a multipronged approach that accounts for societal factors, personal behavior, and policies, as well as genetic and hereditary risks. At UT Southwestern, we plan our patients' heart care with consideration for how these different perspectives affect their health.
We’re not the first to delve into health care disparities, and we will not be the last. But we hope that by continually asking questions and using research and data to quantify modifiable risk factors, the medical community will unite in pushing for positive change.
Eventually, we will reach a time at which the overwhelming evidence spurs providers, patients, and policymakers to make lasting, impactful shifts in the way we deliver equitable care. As we progress toward that day, we will continue to relentlessly challenge the status quo and advocate for our patients' heart health.