More research needed on cardiovascular disease in Asian-Americans, experts say

"Available research shows that subgroups of Asian-Americans are at increased risk of complications and death from cardiovascular disease; however, Asian-Americans are often studied as a group, which masks the differences within this heterogeneous population," according to Latha Palaniappan, M.D., M.S., chair of the American Heart Association's Scientific Advisory on Cardiovascular Disease in Asian-Americans.

Asian-Americans represent 25 percent of all foreign-born people in the U.S. They are projected to reach nearly 34 million by 2050. Major federal surveys have only recently started to classify Asian-Americans into seven subgroups: Asian Indian, Chinese, Filipino, Korean, Japanese, Vietnamese and Other Asian. The first six subgroups together constitute more than 90 percent of Asian-Americans in the U.S., according to the statement.

Palaniappan and her colleagues reviewed published research on Asian-Americans and cardiovascular disease, then identified gaps in knowledge and made recommendations. "We found many disparities among subgroups," Palaniappan said. "If you group all Asian-Americans together, you do not detect these differences."

The statement cites some of the following risk differences between Asian-American subgroups:

• Asian Indians and Filipinos are at greater risk of coronary heart disease compared to the other subgroups.
• Japanese- and Chinese-Americans have lower rates of coronary heart disease but higher rates of stroke.
• Chinese-Americans have lower rates of peripheral arterial disease, or clotting diseases of the leg arteries, than other groups.

The statement identifies research showing that risk factors for Asian-Americans differ compared to Caucasians. For example, body mass index, a common tool for determining risk for cardiovascular disease, is considered normal when it's less than 25 kg/m2 for Caucasians. However, a BMI under 23 kg/m2 may be more appropriate for Asians, she said.

Some studies also show that Asian-Americans metabolize drugs, including those used to treat heart disease, differently than Caucasians and other racial/ethnic groups.

"Looking at this more closely gives us opportunities to improve health disparities among Asian-Americans," Palaniappan said. "We need changes in data collection."

Among the suggested changes: Instead of grouping Asian Pacific Islanders together, separate them into the appropriate groups for more accurate disease characterization.

This is already done in the U.S. Census, according to Palaniappan, but it is not done commonly in hospitals and clinics.

Other recommendations for improving the quality and quantity of data include developing standard Asian-specific measurement tools for things such as acculturation, which indicates how well a certain population has adapted to the U.S. culture, as well as diet.

"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."

The committee also recommends that researchers should "over-sample" Asian-Americans in population-based and clinical trials to ensure that they are well-represented.

We've done an excellent job in researching disparities in other minority groups, but great gaps remain in our knowledge about Asian-Americans," Palaniappan said. "We are making a call to action for national funding organizations that the study of Asian-Americans should be a priority."

Co-authors are: Maria Rosario G. Araneta, Ph.D.; Themistocles L. Assimes, M.D., Ph.D.; Elizabeth L. Barrett-Connor, M.D.; Mercedes R. Carnethon, Ph.D.; Michael H. Criqui, M.D., MPH; Gordon L. Fung, M.D., Ph.D., MPH; K.M. Venkat Narayan, M.D., M.Sc; Hamang Patel, M.D.; Ruth E. Taylor-Piliae, Ph.D., R.N.; Peter W.F. Wilson, M.D.; and Nathan D. Wong, Ph.D.