Medication for Hypercholesterolemia and the Risk of Nonfatal Acute Myocardial Infarction. A Case-Control Study in Japan.

Abstract

levated levels of serum total or low-density lipoprotein cholesterol have been related to increased risk of coronary heart disease (CHD) in many prospective studies in Western countries, [1][2][3][4] and it has been consistently shown in randomized controlled trials that lowering blood cholesterol reduces both the incidence and recurrence of CHD events. [5][6][7][8][9][10][11][12][13] A positive association between serum total cholesterol and CHD has been observed in Asian populations with relatively low levels of serum total cholesterol and at low risk of CHD, 14,15 but it is unclear whether the beneficial effect of lowering blood cholesterol observed in Western populations is directly applicable to Japanese subjects with hypercholesterolemia. A small clinical trial in Japan showed that the use of pravastatin resulted in regression of coronary atherosclerosis, 16 but a randomized controlled trial regarding the prevention of CHD events by medication for hypercholesterolemia has never been successfully completed. 17 We designed a case -control study, the Fukuoka Heart Study, 18,19 to investigate the relationship between medication for hypercholesterolemia and the risk of nonfatal acute myocardial infarction (AMI) in Japanese men and women. MethodsThe study was designed and implemented in accordance with the Declaration of Helsinki adopted by the 18th World Circulation Journal Vol.66, May 2002Medical Assembly; observational studies were not the subject of review by the institutional ethical committee at the time of the survey. Study subjects were patients with a first episode of AMI and matched community controls. Written informed consent was given by all participating individuals. Cases and ControlsEligible cases were patients aged 40-79 years who were admitted to hospital for a first AMI during September 1996 to September 1998 and who recovered well enough to be interviewed within 1 month after the onset of AMI. The eligible cases were originally restricted to residents of Fukuoka City, but were extended to those of 21 adjacent municipalities in June 1997. Thirteen hospitals were selected to cover the patients in Fukuoka City when the study began, and 9 other hospitals outside Fukuoka City were subsequently included. These collaborating hospitals were staffed with one or more expert cardiologists and were equipped with facilities for treating AMI.Research nurses visited each hospital weekly, checked all admissions with a diagnosis of AMI or suspected AMI, and asked eligible patients to participate in the study. Collaborator cardiologists were in charge of the diagnosis of AMI, which was made on the basis of electrocardiographic findings, ischemic cardiac pain lasting at least 30 min, and enzyme changes in accordance with the criteria used in the Lipid Research Clinics Coronary Primary Prevention Trial. 20 Of 756 eligible patients, a total of 660 (87%) participated in the study. Reasons for non-participation were impaired ability to communicate (n=9), discharge before interview (n=65), and refusal (n=22). Two cas...