Author + information
- †Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
- ‡Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- ↵∗Reprint requests and correspondence
: Dr. Sonia S. Anand, Department of Medicine, McMaster University, 1280 Main Street West, MDCL-3204, Hamilton, Ontario L8N 3Z5, Canada.
Heart disease is the leading cause of death in the United States, and stroke is the fourth leading cause of death (1). Together, heart disease and stroke accounted for more than $300 billion in health care expenditures and related expenses in 2010 alone (2). However, from 2000 to 2010, death rates attributable to cardiovascular disease (CVD) declined by 31.0%. In the same 10-year period, the actual number of annual deaths from CVD declined by 16.7% (2). Yet in 2010, CVD still accounted for 31.9% of all 2,468,435 deaths, or about 1 of every 3 deaths in the United States (2). Despite this decline, considerable data from the United States and Canada highlight that the rate of decline and burden of CVD may vary considerably across ethnic groups. The U.S. Federal Government defines “Asian American” as persons having origins in the original Far East, Southeast Asia, or the Indian subcontinent. Asians are the fastest growing ethnic group in the United States and are projected to reach 40 million by the year 2050 (3). Despite this considerable growth, ethnic-specific research among Asians on a national basis has been limited (4,5), partly because of the lack of specificity of the term “Asian,” which has recently been changed to specify the major Asian-American subgroups including Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese Americans.
In this issue of the Journal, Jose et al. (6) present an important new study of ethnic variations and cardiovascular deaths that used death records from 34 states, which reported heart disease and stroke mortality rates for the 6 largest Asian-American subgroups. The investigators examined more than 10 million death records and derived population data for 2003 to 2010 by using linear interpolation from the 2000 and 2010 U.S. Census. They calculated mean standardized mortality ratios (SMRs), relative standardized mortality ratios (rSMR), and proportional mortality ratios (PMRs) for each sex and ethnic group relative to non-Hispanic whites (NHWs). They found that while NHW men and women had the highest overall CVD mortality rates when examined over the study period (2003 to 2010), the SMRs from all CVDs decreased each year for NHW women and men. For Asian-American subgroups, Asian Indian men and women and Filipino men had greater proportionate mortality burden from ischemic heart disease (IHD). Asian Indians, Chinese, and Filipinos had higher proportionate mortality from hypertensive heart disease. During the study period, the slope of the decline in CVD mortality was less among Asian subgroups than among NHWs, and for Asian Indian women it increased, as shown in Figure 1 in the paper by Jose et al. (6).
NHW women had the highest observed number of deaths resulting from cerebrovascular diseases and higher mean age-adjusted annual mortality from cerebrovascular disease compared with Asian women subgroups. NHW men had the highest observed number of cerebrovascular deaths and lower age-adjusted annual mortality rates from cerebrovascular disease compared with Filipino, Japanese, and Vietnamese men. When stratified by stroke subtype, NHW women and men had the highest mortality rates for ischemic stroke. In contrast, both women and men from every Asian subgroup (except Asian Indians) had higher mortality rates and greater proportionate mortality from hemorrhagic stroke than did NHWs. Importantly, there was a consistently higher PMR for deaths from hypertensive heart disease in all Asian women subgroups (except Vietnamese) and for all-cause stroke, especially hemorrhagic stroke compared with NHW women, findings that indicate hypertension is an important risk factor to detect, screen, and treat in Asian-American women.
Particular strengths of this research include the specificity of data for Asian-specific subgroups on a population basis, representing 34 states and 86% of Asian Americans. The results of this study are supported by a sensitivity analysis comparing cause-specific death rates for NHWs in the 34 states with those from all 50 states that showed no substantive or systematic differences.
This work contributes at least 2 important pieces of information to our understanding of ethnic and racial differences in cardiovascular health. First, a disconcerting finding was that in NHWs, deaths from heart disease fell between 2003 and 2010, whereas death rates in Asian-Americans remained the same or, in the case of Asian Indian women, increased over this period. In contrast, Canadian data from an earlier 10-year period, from 1979 to 1983 to 1989 to 1993, indicated decreases in IHD in both men and women of European, South Asian, and Chinese origin, with the most marked decrease seen in South Asians (7). The reasons for the lack of reduction of cardiovascular mortality among Asian-American subgroups are worthy of further study and represent a call to action for continued surveillance of and ethnic-specific research on CVD in the United States. Understanding whether this “uptick” has resulted from changes in life-style (and therefore increased risk factors such as hypertension and diabetes), lower than expected detection and treatment of risk factors, or lower than expected pharmacological treatment of established CVD is important to determine in order to develop population-level prevention strategies. Capewell’s IMPACT model may be particularly useful to understand the effect of risk factor and health behavior trends on CVD rates within specific ethnic groups (8).
Second, this paper raises the question of how to “get the message out” regarding specific risks in Asian-American subgroups. For example, Asian Indians in the United States, Canada, and the United Kingdom exhibit a higher prevalence of abdominal obesity, type 2 diabetes, and low high-density lipoprotein cholesterol values, as well as a greater proportionate mortality from IHD. In Canada, national lipid guidelines recommend that Asian Indians be screened at younger ages (9), because they are at higher cardiovascular risk. Thus, development of national prevention guidelines specifically directed toward Asian-American subgroups is needed. This will raise awareness of risk factors in specific ethnic communities, lead to the development of ethnic-specific nutrition and physical activity programs to prevent weight gain in young adulthood, and increase primary care physicians’ awareness of optimal risk factor targets in Asian populations (10). For Asian Americans, especially Asian Indian, Chinese, and Filipino men and virtually all Asian-American women, a targeted hypertension program involving increasing awareness of the factors that lead to hypertension (e.g., excess weight gain, central adiposity, and physical inactivity) and earlier detection and control of hypertension should be implemented at a population level. This will likely contribute to a significant reduction in overall cardiovascular deaths in these groups.
What are this study’s implications? First, this work emphasizes the substantial differences in cause-specific mortality across subgroups of Asians and underscores the need for finer categorizations of race and ethnicity in population health studies. Broad categorizations such as “Asian” may obscure important differences in risk factor frequency and hence population-attributable risks in such subgroups that comprise vital information for national guideline development, community-based prevention programs, and screening and treatment programs (11,12). Second, the heterogeneous findings across Asian-American subgroups are a call to action for more research into the causes underpinning differences in population-attributable risk and patterns of CVD (e.g., ratio of IHD to stroke and stroke etiology) across specific Asian-American groups. The classic Ni-Hon-San study showed that Japanese immigrants to the United States experienced similar mortality patterns to lifelong U.S. residents, with an increase in IHD and a reduction in stroke mortality compared with Japan. Acculturation to North American life-style changes risk factors and thus the pattern of CVD experienced by immigrants. Traditional Asian Indian, Chinese, or Japanese diets change with acculturation (13,14), as do activity patterns and social networks. These life-style changes affect risk factor prevalence. Etiologic studies of early life determinants of cardiometabolic risk factors, including genetic and epigenetic factors (15), prospective cohort studies linking exposures to subclinical and clinical outcomes (16), and culturally tailored interventions at the primordial and primary prevention levels (17), are needed among high-risk Asian subgroups. Furthermore, after CVD has developed, adherence to evidence-based medical therapies is suboptimal (18). Mixed methods research to understand the perceptions of drug therapy and the barriers to long-term medication use is required to inform culturally tailored strategies to maximize adherence in secondary prevention (19).
The data presented by Jose et al. (6) provide a public health basis for the U.S. Census decision to expand the “Asian” category of race, and they underscore the need to look beyond the traditional 5-category race classification to understand and reduce health care discrepancies. This work provides justification for ethnic-specific public health efforts tailored to specific risk profiles for Asian subgroups. Up-to-date surveillance data at the national, state, and local levels are important for the design, implementation, and evaluation of programs in order to reduce these health care disparities.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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