Objectives: To examine long-term trends in the incidence of coronary heart disease, stroke, and their risk factors among Japanese populations, we explored 32 years of surveillance data for male residents in urban and rural areas in Japan.
Methods: The surveyed populations were 40-79 year-old male residents in M community (population over 40 years old in 1995 was 11,121) of Y City in Osaka (urban area; Osaka) and I town (n = 3,571) in Akita prefecture (rural area; Akita). Incidence rates of coronary heart disease (myocardial infarction, angina pectoris), sudden cardiac death, percutaneous transluminal coronary angioplasty (PTCA) and stroke per 1,000 person-years were calculated for 1964-71, 1972-79, 1980-87 and 1988-95. Risk factors were evaluated by cross-sectional surveys conducted in the median years for each period. Dietary intake was examined by the 24-hour recall method in the latter three periods.
Results: Age-adjusted incidence of coronary heart disease per 1,000 men increased progressively from 0.27 in 1964-71 to 0.90 in 1988-95 (P = 0.222 for trend) among 40-59 year old residents in Osaka. Among their 60-79 year old counterparts, though the incidence was 2.62-3.11 and did not change over the periods studied, the combined rates for coronary heart disease and men who had a PTCA reached 3.79 in 1988-95. In contrast, the incidence of coronary heart disease among Akita residents did not change over time and stroke declined 70 percent between 1964-71 and 1988-95 (P < 0.001) in both 40-59 and 60-79 year age group: The decrease in cerebral infarction was less marked between 1980-87 and 1988-95 among 60-79 year old individuals. Significant increases in diastolic blood pressure, total serum cholesterol, body mass index, salt intake and total fat percent of total energy in Osaka, were associated with the elevation in the incidence of coronary heart disease. In Akita, blood pressure leveled off over the study period, but decreased less during the last decade whereas the prevalence of obesity increased.
Conclusion: Trends in cardiovascular diseases and their risk factors differ among different geographical areas. The present long-term study, in particular, demonstrated an increase in the incidence of coronary heart disease among urban Japanese male residents in Osaka between the 1960s and the 1990s.