title: Relationship between shift work and hypercholesterolemia in Japan.
abstract: OBJECTIVE
  The objective of this study was to clarify the influence of shift work on total cholesterol levels in serum in male Japanese workers.
  
  
  METHODS
  Pooled logistic regression analyses were applied in this 14-year cohort study of 5510 male workers in a steel company. In examining how the adjustments influenced the results, the effect of shift work on the onset of hypercholesterolemia (>or=220 mg/dl, 5.7 mmol/l) was calculated by adjusting only for age (step 1), for age and lifestyle factors (drinking habit, smoking habit, habitual exercise) (step 2), for age, body mass index (BMI), and the laboratory data [creatinine, glycosylated hemoglobin A1c (HbA1c), aspartic aminotransferase, gamma-glutamyl transpeptidase (gamma-GTP), uric acid] (step 3), and for age, BMI, lifestyle factors, and the laboratory data (step 4).
  
  
  RESULTS
  The odds ratio (OR) for shift work with respect to the onset of hypercholesterolemia was significant in step 4 [OR 1.10, 95% confidence interval (95% CI) 1.00-1.21, P-value 0.048], whereas the corresponding odds ratios in steps 1, 2, and 3 were not significant. In step 4, the other significant covariates were age (OR 1.01, 95% CI 1.00-1.02), BMI (OR 1.07, 95% CI 1.05-1.09), HbA1c (OR 1.07, 95% CI 1.02-1.11), gamma-GTP (OR 1.03, 95% CI 1.02-1.04) and alcohol consumption (OR 0.89, 95% CI 0.81-0.99).
  
  
  CONCLUSIONS
  In the present study, shift work was shown to be a potential risk factor for hypercholesterolemia among male Japanese workers. However, no consistent association was found between shift work and hypercholesterolemia in the hierarchical evaluation of the statistical model. The present study could not provide well-established evidence for a relationship between shift work and hypercholesterolemia.
authors.affiliation: Department of Occupational and Environmental Medicine (A2), Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan. muetani@faculty.chiba-u.jp
authors.forename: Mirei
authors.initials: M
authors.lastname: Dochi
authors.forename: Kouich
authors.initials: K
authors.lastname: Sakata
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Oishi
authors.forename: Kumihiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Etsuko
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Suwazono
mesh_terms: D000328:Adult; D015331:Cohort Studies; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000453:epidemiology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012044:Regression Analysis; D012307:Risk Factors; D014940:Work Schedule Tolerance