title: An occupational health study of emergency physicians in Japan: health assessment by immune variables (CD4, CD8, CD56, and NK cell activity) at the beginning of work.
abstract: This study was conducted to evaluate the occupational health of Japanese physicians in emergency medicine. Subjects participating in this study were eighty-nine physicians working at 12 medical facilities (10 critical care emergency centers) in Japan. Participants were asked to complete a questionnaire of work conditions and to provide blood samples for immune variable measurements (CD4, CD8, CD56 and natural killer cell (NK cell) activity) before commencing their work. The data collected from seventy-four of 89 participating physicians were analyzed. The traditional work group comprised of 39 emergency physicians, who were significantly overworked compared to other two groups: the shift work group and the day work group. Among these three groups, no immune variable was significantly different except lymphocyte, number of CD4, and NK cell activity; and the NK cell activity of the shift work group was significantly lower than those of the traditional work group (p<0.01) and the day work group (p<0.01) in terms of Bonferroni's multiple comparison, probably due to circadian rhythm. It was indicated that NK cell activity was significantly lower in samples collected at night versus in the morning (OR=8.34, 95%CI: 1.95-35.6, p<0.01) through multiple logistic regression analyses. NK cell activity was significantly lower in individuals taking 0-3 days off per month, as compared to those taking 4 or more days off (OR=4.65, 95%CI: 1.27-17.0, p=0.02), according to multiple logistic regression analyses. Therefore, the low NK cell activity appears to have reflected the extent of fatigue arising from physicians' overwork. Overwork would have been a potential risk for the physicians' health, resulting in a lower quality of Japanese emergency medical services than that which could have been achieved otherwise. This study suggests that it would be better for the Japanese emergency physicians to take 4 or more days off per month for their health and the quality of their services.
authors.affiliation: Department of Preventive Medicine and Public Health, School of Medicine, Kyorin University, Japan. hph-okamoto@kyorin-u.ac.jp
authors.forename: Hiroteru
authors.initials: H
authors.lastname: Okamoto
authors.forename: Tooru
authors.initials: T
authors.lastname: Tsunoda
authors.forename: Koji
authors.initials: K
authors.lastname: Teruya
authors.forename: Nobuo
authors.initials: N
authors.lastname: Takeda
authors.forename: Takamoto
authors.initials: T
authors.lastname: Uemura
authors.forename: Tomoko
authors.initials: T
authors.lastname: Matsui
authors.forename: Shinji
authors.initials: S
authors.lastname: Fukazawa
authors.forename: Kaoru
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Rieko
authors.initials: R
authors.lastname: Takemae
authors.forename: Kosuke
authors.initials: K
authors.lastname: Tsuchida
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takashima
mesh_terms: D000328:Adult; D002055:Burnout, Professional / Q000453:epidemiology / Q000276:immunology / Q000523:psychology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D019002:CD56 Antigen / Q000097:blood / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007694:Killer Cells, Natural / Q000276:immunology; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000276:immunology* / Q000523:psychology; D010820:Physicians; D011795:Surveys and Questionnaires; D014940:Work Schedule Tolerance / Q000502:physiology*; D016526:Workload
chemical_list: D019002:CD56 Antigen