Coronary heart disease and ethnic identification

Abstract

Over the past two decades, an increasing amount of research has been directed toward discovering the causes of major chronic diseases such as coronary heart disease (CHD) and stroke, or cerebrovascular accident (CVA). Although epidemiologic investigations in the United States and other countries have succeeded in identifying physiological risk factors related to coronary heart disease (e.g., elevated serum cholesterol, high blood pressure, and cigarette smoking), a major problem of many of these studies has been the lack of intrapopulation variability. Early international studies have shown that Caucasian Americans seem to have a higher incidence of CHD in contrast to the Japanese in Japan, and that there exists an increasing CHD mortality rate for those of Japanese ancestry, from Japan to Hawaii to California. The Honolulu Heart Program Study (HHPS) was developed as an effort to study this reported gradient of increased CHD mortality. The original subject sample was comprised of men of Japanese ancestry who were born in the years 1900-1919 and who resided on Oahu in 1965. Interviews were initially conducted to obtain demographic, lifestyle, sociocultural, and medical information along with a standardized cardiovascular exam; subjects have been tracked continuously to the present. Very little research to date has been devoted to investigating the impact of psychosocial variables on the development of CHD; the present study was devised to examine the role of ethnic identity in the pathogenesis of coronary heart disease. A subset (n=4,653) of the original cohort in the HHPS, who filled out the Ethnic Identity Survey (EIS), comprised the target population for the present study. Both the EIS, which served as the attitudinal measure of ethnic identity and behavioral measures of ethnic identity (diet, reading or writing the Japanese language, and years spent in Japan) were examined for the prevalence and incidence of CHD. The results of this investigation showed that having a higher sense of ethnic identity (when each measure of ethnic identity was considered individually and when all were grouped in their various combinations) was negatively associated with CHD prevalence. In contrast to the attitudinal measure of ethnic identity (EIS), higher scores on the behavioral measures of ethnic identity (in particular having a Japanese diet) were found to be significantly related (negatively) to the development of incident coronary heart disease. Some support was also found for a negative relationship between scoring higher on the EIS in combination with two or three behavioral measures of ethnic identity and CHD incidence. A subsample of 121 men from this cohort who had died and had protocol autopsies performed was also examined for atherosclerotic damage of the coronary arteries at the time of autopsy. None of the measures of ethnic identity were found to be associated with atherosclerotic damage, either singularly or in combination. The lack of autopsy results may have been due, however, to the relatively small sample size of subjects or to potential autopsy biases. Although there are a number of potential threats to the validity of this study, inherent in many epidemiological investigations, the results clearly showed that ethnic identity was related to the pathogenesis of CHD. The implications of the present research are discussed in terms of possible directions for future research to identify ethnic identity as an independent risk factor for coronary heart disease.