AHA advisory: CV risk in Asian-Americans demands more research
While the Asian-American population accounts for 25 percent of the total foreign-born individuals in the U.S., targeted research regarding this population and their heart disease risk is limited and more is necessary, according to an American Heart Association (AHA) science advisory published in the Aug. 24 edition of Circulation.

"Available research shows that subgroups of Asian-Americans are at increased risk of complications and death from cardiovascular disease (CVD); however, Asian-Americans are often studied as a group, which masks the differences within this heterogeneous population," according to Latha P. Palaniappan, MD, chair of the AHA's scientific advisory on cardiovascular disease in Asian-Americans. "Because health surveys and questionnaires almost universally combine persons of Asian ancestry into a single group, the heterogeneity within this classification is masked."

The researchers found that current surveys group Asian-Americans into seven subcategories: Asian-Indian, Chinese, Filipino, Korean, Japanese, Vietnamese and other Asians. According to the statement, the first six subgroups account for more than 90 percent of the Asian-American U.S. population.

Palaniappan and colleagues reviewed prior studies and data published that looked at Asian-Americans and cardiovascular disease to bulk up on the scarce amount of research. After review, the researchers found disparities among the seven subgroups.

"If you group all Asian-Americans together, you do not detect these differences," said Palaniappan.

Within the seven subsets, the researchers found that Koreans and Vietnamese were most likely to be uninsured, 36 percent and 18 percent, respectively. Filipinos and Japanese were least likely to be uninsured, 14 percent and 9 percent, respectively.

The researchers found that Asian-Indians and Filipinos exhibited a greater risk of coronary heart disease (CHD) while Japanese and Chinese Americans had higher rates of stroke but lower rates of CHD. However, the researchers noted that data were very limited on coronary artery disease (CAD) incidence within this population suggesting that "some subgroups are at increased risk."

But, results of a California epidemiological study found that mortlaity was higher in a younger, Asian-Indian population of patients compared to other subgroups and racial and ethnic groups. Additionally, this subset had higher rates of ischemic heart disease hospitalizations.

Chinese-Americans had lower rates of peripheral artery disease than the other subgroups studied, as well as lower rates of hospitalizations for ischemic heart disease, the authors found. Compared to whites, Asian-Americans were less likely to undergo PCI and CABG; however, when CABG interventions were performed, Asian-Americans see higher rates of mortality compared to whites.

Palaniappan concluded that Asian-Americans may have different risk factors compared to those of Caucasians and said that while a body mass index of 25 kg/m2 or less is normal for Caucasians, for Asians, a body mass index of 23 kg/m2 may be more appropriate. Additionally, Asian-Americans can often metabolize drug therapy for heart disease differently than other racial and ethnic groups.

While Palaniappan and colleagues found that previous studies have shown that whites and Asian-Americans have similar rates of CVD risk factors, substudies have shown that Filipinos have greater incidences of hypertension compared to other Asian-Americans.

Palaniappan et al concluded that data collection strategies must be revamped to account for these disparities and rather than grouping racial and ethnic groups together.

"In Mexican-Americans and Spanish populations we often use language as a marker as acculturation. We say: Do you speak English at home? This is not such a great marker in Asian populations because English is often taught in the home countries. In India, for example, English is a national language," Palaniappan said. "Giving many Asian-Americans the typical American diet questionnaire does not lead to accurate data collection because these questions do not reflect culturally specific foods."

Diet may also play a part in differentiations of CV risk within racial and ethnic groups. For one, Asian-Americans have been found to have lower rates of physical activity compared with non-Hispanic whites, Hispanics and African-Americans. 

The researchers recommended that better standards and  measurement tools be utilized and also said that researchers should “over-sample’ Asian Americans in clinical trials to ensure they are properly represented.

"Study of Asian-Americans offers important opportunities and challenges for CVD research," the authors concluded. "Specific opportunities to improve the assessment of health disparities among Asian Americans include but are not limited to the following: changes in existing data collection, the development of standard measurement tools, and the development of new research studies."