Spectrum of Cardiovascular Diseases in Asian-American Racial/Ethnic Subgroups

Purpose

To compare the prevalence of coronary heart disease (CHD), stroke, and peripheral vascular disease (PVD) across Asian-American subgroups (Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese) and non-Hispanic white (NHW) subjects in a mixed-payer, outpatient health care organization in California.

Methods

Electronic health records from 2007 to 2010 were examined for 94,423 Asian and NHW patients. Age-adjusted prevalence rates of CHD, stroke, and PVD, defined by physician International Classification of Diseases, Version 9, codes, were directly standardized to the NHW population. Age-adjusted odds ratios were calculated by the use of logistic regression for each Asian subgroup, by sex, compared with NHWs.

Results

The range of age-adjusted prevalence rates were: CHD (1.7%−5.2%), stroke (0.3%−1.8%), and PVD (0.9%−3.4%). The adjusted odds ratios of CHD were significantly higher for Filipino women (1.66; 95% confidence interval; 1.13−2.43) and men (1.47, 1.05−2.06) and Asian Indian men (1.77, 1.43−2.21), and significantly lower for Chinese women (0.72, 0.55−0.94) and men (0.78, 0.65−0.93), compared with NHWs. The odds of stroke were significantly greater for Filipino women (2.02, 1.22−3.34). The odds of PVD were generally lower for all Asian subgroups.

Conclusion

There is considerable heterogeneity across Asian subgroups for prevalent CHD, stroke, and PVD. Future research should disaggregate Asian subgroups and cardiovascular outcomes to inform targeted prevention and treatment efforts.

Introduction

Asian Americans are the fastest growing racial/ethnic group in the United States, with a population of more than 14 million that is projected to reach nearly 34 million by 2050 (1), and more than one-third (4.7 of 14.1 million) of all Asian Americans live in California (2). The Asian-American population is racially and ethnically heterogeneous, with the six largest subgroups (Asian Indian, Chinese, Filipino, Korean, Japanese, and Vietnamese) comprising approximately 90% of Asian Americans (3).

Much of our knowledge of cardiovascular disease (CVD) in Asian Americans, however, has been determined by studies in which the authors have either grouped Asian Americans together or examined one subgroup alone. National registries of CVD, such as the National Registry of Myocardial Infarction and the Paul Coverdell National Acute Stroke Registry, only report data for aggregated Asian Americans, masking possible heterogeneity among the subgroups 4, 5. In large-scale epidemiologic studies of CVD among Asian Americans, such as the Multi-ethnic Study of Atherosclerosis (MESA) (6) and the Honolulu Heart Program (7), authors have examined one Asian subgroup alone (Chinese and Japanese, respectively), precluding comparisons across subgroups. Research findings determined by the aggregated Asian-American group or one subgroup alone are often presumed to be applicable for all other subgroups.

The only nationally representative data for CVD among Asian Americans comes from the National Health Interview Survey (NHIS). According to the 2008 NHIS, national prevalence rates for coronary heart disease (CHD) and stroke among adults 18 years of age and older are 2.9% and 1.8%, respectively, for aggregated Asian Americans, compared with 6.5% and 2.7% for Non-Hispanic white (NHW) subjects (8).

Barnes et al. (9) used NHIS data from 2004 to 2006 to determine national estimates of heart disease and stroke among Asian subgroups. However, because of small sample sizes in some Asian subgroups, the NHIS data do not produce statistically stable estimates for some subgroup-level analyses of heart disease and stroke (9). In addition, NHIS is based on self-reported data and does not include clinical records, which may lead to underestimated prevalence rates of CVD (10). Currently there are no publicly available data sources that are large enough to provide prevalence rates for CHD, stroke, and peripheral vascular disease (PVD) for Asian-American subgroups 9, 11.

Although few studies have examined Asian-American subgroups individually, the limited data available suggest variation in the prevalence of CHD, stroke, and PVD across Asian subgroups. Various small studies in which the authors have examined a few specific subgroups have shown greater rates of CHD in Asian Indians 12, 13 and Filipinos (12), greater rates of hemorrhagic stroke among Chinese (14), and lower rates of CHD and PVD among Chinese 12, 15, compared with NHW subjects. These studies, however, have generally focused on one or two subgroups alone. In addition, differences in methods and population selection make it difficult to make comparisons of subgroups across studies. The objective of this analysis was to use a single data source to determine and compare the relative prevalence of CHD, stroke, and PVD across Asian-American subgroups (Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese) and NHW subjects from a large mixed-payer, outpatient health care organization in California.