Objective: There is little evidence concerning risk factors for sudden cardiac death (SCD) among Asians.
Patients and methods: A prospective, nested, case–control study of Japanese patients aged between 30 and 84 years was undertaken using data collected from 26 870 participants in cardiovascular risk surveys conducted in four communities between 1975 and 2005. The incidence of SCD was ascertained by systematic surveillance, with 239 cases of SCD identified over this period. For each case of SCD, three control patients were selected, matched by age, sex, examination year, follow-up time, and community.
Results: Hypertension, diabetes mellitus, smoking, major ST-T abnormalities, left high amplitude R waves, and increased heart rate (≥77 beat/min) were all independently associated with a 1.5–3.2-fold increase in SCD risk, whereas no associations were observed for body mass index and hypercholesterolemia. The population-attributable fraction [95% confidence interval (CI)] was 23.0% (2.9–39.0) for hypertension, 15.3% (3.8–25.5) for current smoking, 14.5% (8.0–20.5) for major ST-T abnormalities, and 8.1% (2.2–13.7) for diabetes mellitus. The number of SCD risk factors (hypertension, diabetes, smoking, and ECG abnormalities) was positively associated with increased SCD risk. The odds ratio for increased SCD risk with three or more risk factors versus zero risk factors was 5.76 (95% CI 3.20–10.39).
Conclusions: Among the Japanese population, hypertension, smoking, major ST-T abnormalities, left high amplitude R waves, and diabetes mellitus were associated with an increased incidence of SCD, whereas there were no associations of body mass index or hypercholesterolemia with SCD incidence.
aDepartment of Social and Environmental Medicine, Osaka University, Suita
bOsaka Medical Center for Health Science and Promotion, Osaka
cDepartment of Public Health Medicine, University of Tsukuba, Tsukuba
dDepartment of Pharmaco-Business Innovation, The University of Tokyo, Tokyo
eDepartment of Hospital Management Strategy and Planning, Nagoya University, Nagoya, Japan
Correspondence to Tetsuya Ohira, MD, PhD, Department of Social and Environmental Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Tel: +81 6879 3911; fax: +81 6879 3919; e-mail: firstname.lastname@example.org
Abbreviations: BMI, body mass index; CHD, coronary heart disease; CI, confidence interval; CIRCS, Circulatory Risk in Communities Study; ECG, electrocardiogram; LHAR, left high amplitude R waves; OR, odds ratio; PAF, population-attributable fraction; SCD, sudden cardiac death; ST-T, ST-segment and T-wave; SVPC, supraventricular premature contraction; VPC, ventricular premature contraction
Received 13 June, 2011
Revised 17 January, 2012
Accepted 16 February, 2012