Study Category: The Cohort Studies (1947-1972)
Year Begun: 1965
Location: Hiroshima and Nagaski, Japan; Honolulu, HI, USA, San Francisco Bay Area, CA, USA
Principal Investigator(s): NIHONSAN Study Group
Many Japanese migrated to the United States in the late nineteenth and early twentieth century and have since been the focus of migrant studies on chronic disease in attempts to separate genetic and environmental influences. International comparisons revealed that white Americans have a high incidence of coronary heart disease (CHD), while Japanese living in Japan have a relatively low incidence.  The NIHONSAN Study, in a prospective cohort design, compared three groups of men, aged 45-69: Japanese living in Japan, Hawaii or the Bay Area of California and assessed their distribution of CVD risk factors and CHD incidence and mortality.
Cohorts were samples of the Adult Health Study from the Atomic Bomb Casualty Commission in Hiroshima and Nagasaki, Japan, the Honolulu Heart Program participants, and a group ascertained by a special census of Japanese-Americans living in the San Francisco Bay area counties.  A total of 11,989 subjects was examined, with 2,141 from Japan (80% response rate), 8,006 from Hawaii (72% response rate) and 1,842 from California (68% response rate).  At baseline, each participant received a complete physical examination, an ECG and urinalysis, measurements of weight, height, skinfold thickness, blood pressure and serum cholesterol level. Subjects were also given a self-administered questionnaire on socioeconomic and demographic characteristics and a medical history administered by a medical professional. 
Twenty-year mortality comparisons were made using data from a migrant study by Tavia Gordon [ ] and from the Framingham Study.  Data from a 16-year follow up of the Framingham Study cohort were used as the referent group for comparison with the Japanese and Japanese migrants. CHD mortality for American Caucasian men typically ranged from 8-10 deaths per 1000, while Japanese men experienced CHD incidence at a rate of 1 per 1000, from 1950-1970. Among Japanese, men living in San Francisco experienced the highest CHD incidence (5 cases per 1000 men), followed by Hawaii (4.5 cases per 1000 men) and mainland Japan (2 cases per 1000 men).  Among Japanese, men living in California had the highest age-adjusted prevalence of CHD, with 10.8 cases per 1000, followed by Japan (5.3) and Hawaii (5.2). Californian Japanese also had the highest prevalence of angina pectoris (25.3 per 1000 men) and possible infarction (31.4 per 1000 men). 
Across all age groups, cholesterol, blood glucose and uric acid levels were all significant risk factors for CHD when comparing the mainland Japanese and Hawaiian and Californian study populations (p-values < .01)  When comparing Californian and Hawaiian Japanese, however, glucose and uric acid were not significant risk factors, and the significance of cholesterol varied across age groups. [4,5]
Strengths of the study included uniform data collection across a number of test centers, high response rate and high retention rate of subjects in the study. The hypothesis was supported that CVD risk levels and disease rates among migrants approached those of the host populations and their differences were thus primarily environmental in origin, not genetic. (HB)
 Trombold, J.C., Moellering, R.C. Jr., and Kagan, A., 1966. Epidemiological aspects of coronary heart disease and cerebrovascular disease: The Honolulu Heart Program. Hawaii medical journal 25 (3), 231-234.
 Syme, S.L., Marmot, M.G., Kagan, A., Kato, H., and Rhoads, G., 1975. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: introduction. American journal of epidemiology 102 (6), 477-480.
 Marmot, M.G., Syme, S.L., Kagan, A., Kato, H., Cohen, J.B., and Belsky, J., 1975. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: prevalence of coronary and hypertensive heart disease and associated risk factors. American journal of epidemiology 102 (6), 514-524.
 Nichaman, M.Z., Hamilton, H.B., Kagan, A., Grier, T., Sacks, T., and Syme, S.L., 1975. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: distribution of biochemical risk factors. American journal of epidemiology 102 (6), 491-501.
 Worth, R.M., Kato, H., Rhoads, G., Kagan, A., and Syme, S.L., 1975. Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: mortality. American journal of epidemiology 102 (6), 481-490.