The epidemic of diabetes and atherosclerotic cardiovascular disease in Asian Americans- Our voices must be heard!

In 2010, the American Heart Association (AHA) scientific advisory statement entitled “A Call to Action: Cardiovascular Disease in Asian Americans” was published calling for the health care community to recognize the importance of assessing atherosclerotic cardiovascular disease (ASCVD) risk in Asian Americans (AsA) ^[1]. The statement specifically addressed the need to disaggregate AsA subgroups to better understand the heterogeneity in cardiovascular (CV) mortality and risk factor prevalence. The recently published statement on the epidemiology of type 2 diabetes (T2D) and ASCVD among Asian American adults provides a barometer for the progress we have made with advancing research on ASCVD risk among AsA subgroups and improving clinical outcomes (NEED CITATION). Unfortunately, as summarized below, we have barely moved the needle.

Asian people account for 60% of the world’s population and 7.2% of the US population ^[2]. Chinese (4.1 million), Asian Indians (4 million), Filipinos (2.9 million), Vietnamese (1.8 million), Korean (1.5 million), and Japanese Americans (0.8 million) represent 87% of the AsA population in the US. By 2050, AsA adults will be the largest immigrant group and represent 36% of all US immigrants ^[3]. The history of AsA immigration to the US is as varied as our differences in CV morbidity and mortality. It is important to recognize that AsA people are highly concentrated in California, Hawaii, New Jersey, New York, and Texas- states that may be the best incubators for research in AsA communities. From a socioeconomic perspective, AsA households earn more than non-Hispanic (NH) White households, but when we look more closely, we see that there are significant disparities in income levels, educational attainment, and other social determinants of health including food security and health care access ^[3-7]. Disaggregation of AsA subgroups is essential to better understanding how these differences translate to risk of T2D and ASCVD.

To understand distinctions among AsA subgroups requires sufficient participation in clinical trials and registries. Despite the AHA Call to Action statement in 2010, the overall response to increase awareness about ASCVD and disaggregation of AsA subgroups in research studies has been disappointing. The National Health and Nutrition Examination Survey (NHANES) oversampled AsA adults between 2011 through 2018 with four waves of data collection biennially, but due to low numbers, studies of AsA subgroups require combining these datasets which limit the analysis for some populations ^[8]. What conspicuously stands out from this statement is that we have insufficient data to understand why differences in prevalence of T2D, ASCVD, and CV risk factors exist among AsA subgroups.

The epidemiology of T2D for AsA people is derived from less than optimal data sources- health system prevalence estimates, small cohort studies, and a few state and national level surveillance surveys. Disaggregated AsA subgroup data is limited, but shows a general pattern of higher T2D prevalence for Native Hawaiian/Pacific Islands, South Asians, and Southeast Asians but lower prevalence for East Asian people originating from China, Japan, and Korea ^{[8, 9]}. Given the high risk of T2D for AsA people, the US Preventive Services Task Force updated their screening recommendation from age 40 to 35 years for AsA adults with BMI ≥23 kg/m2 ^[10]. Biological mechanisms to explain higher T2D risk for South Asians include higher levels of hepatic and intramuscular fat associated with less lean mass and predisposition to insulin resistance and lower insulin secretion ^[11-17].

Coronary artery disease (CAD) prevalence is highest for South Asians who present with a first clinical event up to 6 years earlier than people from Western Europe or East Asia ^[18]. Subclinical CAD, as documented by coronary calcium score or carotid imaging, also happens more frequently in South Asian people compared to other Asian subgroups ^{[19, 20]}. It was recently reported that South Asian men and women in the US had the highest CV mortality rates compared to all other Asian subgroups and the rates were higher for South Asian women than NH-White women ^[21]. These disturbing trends highlight the current deficiencies with ASCVD risk estimation. While the ACC/AHA 2019 Guideline on Primary Prevention of Cardiovascular Disease recommends use of the pooled cohort equation (PEC) to estimate ASCVD risk, the calculator is only calibrated for NH-White and NH-Black people ^[22]. No accurate risk estimation exists for Asian or Hispanic people leading to overestimation or underestimation of risk for specific Asian and Hispanic subgroups. While being of South Asian decent is considered an ASCVD risk enhancer in the prevention guideline, it is not explicitly stated how much this should influence clinical decision making for blood pressure and cholesterol treatment targets.

While stroke risk is higher for AsA people than NH-White people, considerable heterogeneity exists- the highest risk for Filipino and Vietnamese men and Japanese and Vietnamese women ^[23]. Phenotypic expression of stroke also differs by Asian subgroups with very high risk of intracranial hemorrhage for Filipino adults and subarachnoid hemorrhage for Japanese adults ^[23]. Asian people are more likely to have severe strokes with higher morbidity and mortality and longer hospital stays, but are less likely to receive aggressive treatment, e.g., thrombolysis ^[24]. Very limited data exist for AsA subgroups and prevalence of peripheral arterial disease (PAD). Overall, PAD prevalence is low for AsA adults, but limited data indicates that South Asian adults are at higher risk than other Asian subgroups ^{[25, 26]}.

The statement provides a comprehensive overview of other key ASCVD risk factors including obesity, hypertension and hyperlipidemia. It also reviews other modifiable and non-modifiable risk factors including genetics, acculturation and lifestyle, and social networks. Specific interventions for diet, physical activity, tobacco cessation, sleep, and stress are also discussed. The importance of complementary and alternative medicine (CAM) in AsA adults is highlighted since it is frequently utilized but rarely discussed during clinic visits. Very few studies about diet, physical activity, tobacco cessation, and sleep health have been performed and most without disaggregated AsA subgroups. The key takeaway is that considerable heterogeneity exists in the prevalence of ASCVD as well as modifiable and non-modifiable risk factors in the context of limited clinical data.

The authors provide a nice summary of research opportunities that includes development of culturally tailored measurement tools, disease outcomes research, and creation of more accurate risk assessment tools. The keys to success will require more than just a statement to achieve meaningful results. While it may draw the attention of a few who have an interest in T2D and CV disease in AsA people, we must advocate for changes at the state and federal levels. The South Asian Heart Health Awareness and Research Act of 2021 (H.R. 3771) was first introduced to the House of Representatives in 2017 to provide research funding to improve CV health for South Asian people in the United States ^[27]. Five years later, it still has not been appropriated by the legislature even though the funding request is for a paltry one million dollars/year over a five-year period.

We must push our organizations, including the AHA, American College of Cardiology (ACC), American Diabetes Association, and others to lobby for meaningful research funding for the AsA community and mandate that all clinical trials and government sponsored studies to include accessible disaggregated AsA subgroup information. We must push for renewed oversampling of AsA participation in NHANES and other national surveillance surveys. The National Institutes of Health recently announced a new epidemiological cohort study to address key population health gaps for Asian Americans, Native Hawaiians, and Pacific Islanders ^[28]. While not specific for Asian people, the new Federal legislation that has been proposed to increase diversity in clinical trials is a sign that progress is being made ^[29]. Finally, journals targeting Asian health issues are emerging, including the Journal for Asian Health and the Journal of the American College of Cardiology Asia. They provide visibility to the broader scientific and medical communities and raise awareness about AsA health.

Clinicians and scientists need a visible platform to promote and build research networks for those interested AsA health. It is time for ACC, AHA and others to create working groups and programs committed to AsA CV disease and risk factors. Engagement with Asian medical societies may provide context for how risk factors are treated differently and what culturally specific interventions are promoted. For example, the 2020 Lipid Association of India Expert Consensus Statement on Dyslipidemia Management in Indians recommended the lowest LDL-C target <30 mg/dL for extreme risk patients given the high CV morbidity and mortality in their country ^[30]. Collaboration with investigators from Asian countries who have developed their own ASCVD risk tools can inform unique risk factors and biomarkers that could be tested in AsA populations.

In summary, the AHA Scientific Statement on the Epidemiology of Diabetes and Atherosclerotic Cardiovascular Disease Among Asian American Adults provides an excellent overview of the current state of T2D and ASCVD for AsA adults but more importantly reveals the major challenges we face to make any substantive progress. We can no longer sit idly, but must stand up and advocate for more AsA health research funding and demand inclusion of disaggregated AsA subgroup information for all clinical trials and government sponsored research.