American Journal of Epidemiology Advance Access originally published online on May 17, 2006
American Journal of Epidemiology 2006 164(2):128-135; doi:10.1093/aje/kwj185
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Original Contribution |
A Prospective Cohort Study of Shift Work and Risk of Ischemic Heart Disease in Japanese Male Workers
1 Department of Preventive Medicine and Community Health, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan
2 Public Health, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
3 Department of Preventive Medicine/Biostatistics and Medical Decision Making, Field of Social Life Science, Program in Health and Community Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan
4 Department of Epidemiology and Environmental Health, Juntendo University School of Medicine, Tokyo, Japan
5 Department of Health and Environmental Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
6 Department of Clinical Epidemiology, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan
7 Fukuoka Institute of Health and Environmental Sciences, Dazaifu-shi, Fukuoka, Japan
Correspondence to Dr. Yoshihisa Fujino, Department of Preventive Medicine and Community Health, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahata-nishi-ku, Kitakyushu 807-8555, Japan (e-mail: zenq{at}med.uoeh-u.ac.jp).
This study prospectively examined the association between shift work and the risk of ischemic heart disease among Japanese male workers. A baseline survey, which involved 110,792 inhabitants (age range: 40–79 years) from 45 areas throughout Japan, was conducted between 1988 and 1990. The causes of death were identified from death certificates. The analysis was restricted to 17,649 men (age range: 40–59 years) who were employed at the time of the baseline survey. All subjects were asked to indicate the most regular shift work that they had undertaken previously: day work, rotating-shift work, or fixed-night work. The Cox proportional hazards model was used to estimate the risks of shift work for ischemic heart disease. During the 233,869 person-years of follow-up, a total of 1,363 deaths were recorded, 86 of which were due to ischemic heart disease. Compared with the day workers, the rotating-shift workers had a significantly higher risk of death due to ischemic heart disease (relative risk = 2.32, 95% confidence interval: 1.37, 3.95; p = 0.002), whereas fixed-night work was not associated with ischemic heart disease (relative risk = 1.23, 95% confidence interval: 0.49, 3.10; p = 0.658). In addition, subjects with coronary risk factors, such as hypertension, overweight, habitual alcohol consumption, and smoking, were highly susceptible to the effect of rotating-shift work on the risk of death due to ischemic heart disease.
cardiovascular diseases; circadian rhythm; cohort studies; Japan; myocardial ischemia
Abbreviations: CI, confidence interval; ICD-10, International Classification of Diseases, Tenth Revision; JACC Study, Japan Collaborative Cohort Study for the Evaluation of Cancer Risk