besity is a risk factor for coronary heart disease (CHD) among adults 1 and is increasing in prevalence among young adults, as well as adults. 2,3 A recent report indicated a significant association of obesity with coronary atherosclerosis in young male adults, particularly in those with a central pattern of adiposity, and little association of obesity with coronary atherosclerosis in young female adults. 4 Still another recent report points out that adiposity and its metabolic disturbances (ie, metabolic syndrome) are associated with early atherosclerotic change in adolescents. 5 Recently we demonstrated that young Japanese patients with acute myocardial infarction (AMI) have a higher body mass index (BMI) compared with older patients, 6 but it remains uncertain whether obesity is a CHD Circulation Journal Vol. 70, December 2006 risk factor in young adults as well as older adults in Japan.The AMI-Kyoto Multi-Center Risk Study, a large multicenter observational study in which 16 collaborating hospitals in Kyoto Prefecture have collected demographic, procedural, and outcome data on AMI patients, was established in 2000 in order to analyze these data and establish an emergency-hospital network for heart diseases in Kyoto. 6,7 The Kyoto Citizen's Health and Nutrition Study was performed among residents in Kyoto Prefecture, in order to examine behavior and lifestyle habits and develop effective public health intervention. 8,9 In the present study we used cases from the AMI-Kyoto Multi-Center Risk Study, and controls from the Kyoto Citizen's Health and Nutrition Study, respectively, to assess obesity as a risk factor for AMI in subgroups of 20-year age bands of each gender separately, based on a multi-center case -control study.
Methods
Case and Control SubjectsFrom January 2000 to June 2004, 1,651 consecutive patients with a diagnosis of AMI, who were admitted to AMIKyoto Multi-Center Risk Study Group Hospitals within 1 week after the onset of AMI, were enrolled in the present Background It remains uncertain whether obesity is an independent risk factor for coronary heart disease in young adults, as well as adults, in Japan.
Methods and ResultsIn the present study, 1,260 cases of acute myocardial infarction (AMI) and 3,775 community controls were recruited from the AMI-Kyoto Multi-Center Risk Study and Kyoto Citizen's Health and Nutrition Study, respectively. Obesity and other risk factors were retrospectively examined between cases and controls in each subgroup of young males (20-40 years), middle-aged males or females (40-60 years), older males or females (60-80 years), and very old males or females (80-100 years). In young, middle-aged, and older males, as well as in older females, cases had a higher body mass index (BMI) than controls. In young males, as well as in middle-aged and older females, cases had a higher prevalence of smoking than controls. Except for very old males, the prevalences of hypercholesterolemia, hypertension, and diabetes mellitus were higher in each subgroup of cases than in controls. M...