title: A prospective cohort study of shift work and risk of ischemic heart disease in Japanese male workers.
abstract: 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.
authors.affiliation: Department of Preventive Medicine and Community Health, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan. zenq@med.uoeh-u.ac.jp
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Fujino
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Inaba
authors.forename: Akio
authors.initials: A
authors.lastname: Koizumi
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Kubo
authors.forename: Takesumi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D014940:Work Schedule Tolerance