Studies indicate differences among racial and ethnic groups in type of pulmonary arterial hypertension (PAH) diagnosed, treatments used and outcomes.
by Phyllis Hanlon, Contributing Writer
Some medical researchers have begun studying differences in certain diseases among racial and ethnic groups to create better treatment plans for different health conditions and move toward more targeted treatments. Through two recent studies, researchers hoped to gain a better understanding of the presentation, severity and treatment of patients with WHO Group 1 PH (pulmonary arterial hypertension) among varying racial and ethnic groups.
Nadine Al-Naamani, MD, MS, from the Perelman School of Medicine at the University of Pennsylvania, a PHA-accredited Center of Comprehensive Care, led a team that reviewed data on 1,837 patients who were enrolled in the National Biological Sample and Data Repository for PAH (PAH Biobank) (https://www.pahbiobank.org/), an ongoing project funded by the National Institutes for Health (NIH) (www.nih.gov). (http://journals.sagepub.com/doi/pdf/10.1177/2045893217732213)
In this study, 1,439 subjects were Non-Hispanic White; 210 were African-American; and 188 were Hispanic. The data showed a difference in the type of PAH that people in each racial group had. For example, African-American patients enrolled in the PAH Biobank were more likely to have connective tissue disease-associated PAH; Hispanic patients were more likely to have congenital heart disease-associated PAH; and Non-Hispanic White patients were more likely to have familial PAH and PAH associated with toxins or drug use.
Dr. Al-Naamani and her team found that different treatments were used among the racial groups included in the analysis. They noted that 78 percent of African-American patients received targeted PAH medications; 70 percent of Non-Hispanic White received targeted PAH medications; and 57 percent of Hispanic patients received targeted PAH medications.
The authors reported that the PAH Biobank did not capture socioeconomic factors, such as access to care and health insurance, which could impact the patients’ ability to receive early care and treatment, ultimately affecting the outcome. Dr. Al-Naamani pointed out that although this study looked at a large group of subjects, the PAH Biobank did not include all racial and ethnic groups, and patients’ ethnicity was determined based on their medical records. Some people included in the study could have been incorrectly categorized. Despite these shortcomings, she indicated that the findings from the study suggest that identifying “…disparities in PAH is the first step in eradicating them.”
Ethnic Differences in Presentation and Type of Disease
Sarah K. Medrek, MD, and Sandeep Sahay, MD, conducted additional research on the issue of ethnicity in PAH and how more targeted treatments and treatment strategies can be developed when clinicians better understand how the disease presents in various ethnic groups. (https://www.ncbi.nlm.nih.gov/pubmed/28887060) Dr. Sahay is affiliated with Weill Cornell Medical College and Houston Methodist Hospital, a PHA-accredited Center of Comprehensive Care.
The authors reported on papers published from U.S.-based registries, including the NIH registry, the Surveillance of PAH study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4122278/) the REVEAL (Registry to Evaluate Early and Long-Term PAH Disease Management) registry (https://www.ncbi.nlm.nih.gov/pubmed/26066077), and the PAH Biobank mentioned above. One paper reported that, compared to the general population, African-American patients were overrepresented and Hispanics and Asian/Pacific Islanders were underrepresented in the REVEAL registry.
When the authors broke PAH down into subtypes, they found that connective tissue disease-associated PAH especially showed differences between races/ethnicities. Specifically, they cited a U.K. study that analyzed differences between patients with scleroderma-associated PAH (SSc-PAH). Patients with SSc-PAH who did not have other lung diseases were 96 percent white. SSc-PAH patients who did have other types of lung disease (e.g., interstitial lung disease) were found to be only 80 percent white.
Citing epidemiologic data on primary pulmonary and secondary pulmonary hypertension collected over several decades, the authors note that African-Americans, particularly African-American women, appear to have increased mortality. However, follow-up data from the REVEAL registry suggests the opposite — that white patients have increased mortality. The authors note that socioeconomic factors are important when discussing ethnicity and PAH outcomes and call for the need for this information to be included in future studies. Drs. Medrek and Sahay cited some U.S. studies that report African-American patients with connective tissue disease-associated PAH are more likely to be younger compared to white patients, and frequently have worse disease.
Better Understanding Leads to Targeted Treatment
The authors emphasized the importance of understanding differences in disease presentation and treatment response between different racial and ethnic groups. They cited the Multi-Ethnic Study of Atherosclerosis: MESA, (https://www.mesa-nhlbi.org/) which has offered some insight into potential underlying causes of heart and lung differences in various ethnicities. The research found that events before and during childbirth, such as preeclampsia (high blood pressure and large amounts of protein in the urine during pregnancy) or hypoxia (inadequate oxygen supply) might cause pulmonary problems later in life. Genetic differences, cardiac and lung blood vessel structure might also account for racial and ethnic differences in PAH outcomes. Furthermore, there could be differences in how stiff the heart muscle is when squeezing as Asian, African-American and Hispanic individuals age.
Drs. Medrek and Sahay referred to a study (https://www.ncbi.nlm.nih.gov/pubmed/21940766) looking at differences in endothelin (a chemical in the body that causes the blood vessels in the lungs to tighten) between racial groups. They found that healthy African-American individuals had higher endothelin-1 levels compared to white individuals. This analysis suggested that African-American patients who received endothelin-receptor antagonist (ERAs) might experience a decrease in the six-minute walk distance (6MWD) of 3.5 meters, compared to a 6MWD improvement of 41.5 meters in white patients. They suggested that this could be explained by inadequate dosing of ERA in African-American patients included in the analysis. Nitric oxide is another target in PAH treatment that can vary between racial groups. The authors noted that studies have shown that African-American patients are less likely to respond acutely to nitric oxide.
The authors of both studies agree that greater racial and ethnic diversity in clinical trials is necessary to help clinicians gain clearer understanding of the differences in the way PAH develops, and in how individuals respond, so targeted treatment options can be designed.
Each PH patient is different. It is essential that you talk to your own doctor about what treatment options are best for you. For more information on finding a doctor or an accredited care center, visit https://www.phassociation.org/PHCareCenters/Patients.