August 25, 2010 (Palo Alto, California) — Asian Americans, who represent nearly one-quarter of all foreign-born individuals in the US, are insufficiently studied in cardiovascular medicine, according to a new advisory from the American Heart Association (AHA) [1]. The limited data available, cautions the AHA, tend to lump all Asian Americans into one category, and as a result miss some important differences in risk, treatment patterns, and outcomes across this heterogeneous population.
"Asian Americans are a large and rapidly growing portion of the American population," Dr Latha Palaniappan (Palo Alto Medical Foundation Research Institute, CA), the chair of the scientific advisory on cardiovascular disease in Asian Americans, told heartwire . "Asian Americans are a very diverse group, and by lumping them all together very important differences in disease risk are lost. In order to really get an idea of what the actual disease risks are, these diverse subgroups need to be separated and examined individually."
Published online August 23, 2010 in Circulation, the new report notes that the number of Asian Americans in the US is expected to reach 34 million by 2050. Some federal surveys separate Asians into a number of distinct subgroups, including Asian Indian, Chinese, Filipino, Korean, Japanese, Vietnamese, and others. At present, there are more than three million Chinese Americans, the largest subgroup; approximately 2.5 million Asian Indians and Filipinos; 1.5 million Korean and Vietnamese Americans; and 700 000 Japanese Americans.
Not All Asian Americans Are the Same
To heartwire , Palaniappan said that Asian Americans tend to be considered a "model minority," mainly because it was believed they were more affluent or had higher levels of education. However, when the data are separated out, as is done on the US census, there are significant variations within the racial/ethnic demographic, including significant differences in socioeconomic status.
"The few studies that have been done--a small group here and a small group there--suggest that Asian Indians and Filipinos are at higher risk of heart disease, while Chinese and Japanese individuals are at higher risk for certain types of stroke," said Palaniappan. "We're finding that the disease patterns are different. Different groups have different patterns of disease, so it's important to disaggregate the groups and disaggregate the disease."
In addition to the absence of data on the distinct subgroups, the existing data tend to focus on geographically distinct individuals, such as Chinese Americans in New York City, for example, and are not easily extrapolated to the same racial/ethnic group in another part of the country.
Importantly, Palaniappan stressed that the differences between the Asian subgroups are not simply the result of genetics but include variations in exercise habits and diet, as well as aspects of culture and tradition unique to each group. Acculturation, where a foreign-born person adopts values, customs, and behaviors of the new country--in this case, a Westernized diet with limited physical activity--might differ across Asian Americans and might also differ from other ethnic/racial groups in the US.
Drug Metabolism and BMI
Clinically, Palaniappan said that doctors should be aware of differential body-mass-index (BMI) cut points. Asians, in general, have more fat for every BMI level, and being fatter puts them at a higher risk for developing metabolic problems, such as diabetes and dyslipidemia. As a result, doctors should watch for such conditions developing at lower BMIs.
In addition, there are differences in drug metabolism in the different subgroups. Commonly used cardiac drugs such as propranolol, warfarin, and nifedipine are metabolized differently in certain Asian American subgroups, and there is not enough available research to make clear recommendations for alternate dosing or monitoring.
"The doses used tend to be lower for the same effect, and it's not just because they're smaller, but because their metabolism is different, and the rate of side effects was noted to be higher," said Palaniappan. The JUPITER trial, a large primary-prevention trial that studied rosuvastatin (Crestor, AstraZeneca), also did not enroll patients in Asia (enrollment began in 2003) due to concerns about dosing safety in this group. Smaller primary-prevention studies with rosuvastatin have since been done in Asian individuals, with no unique safety issues observed, according to experts.
Going forward, the AHA says the distinction among the Asian American subgroups should be noted on death certificates, hospital-discharge information, and population-based studies. In addition, the National Registry of Myocardial Infarction should identify the specific Asian subgroups, as should the yet-uncreated national stroke registry. She said this would not involve collecting extra data but simply classifying what is already collected better.
Heartwire from Medscape © 2010 Medscape, LLC
Cite this: AHA Issues Call to Action on CVD Research in Asian Americans - Medscape - Aug 25, 2010.
