title: Association between shift work and obesity among female nurses: Korean Nurses' Survey.
abstract: BACKGROUND
  Shift work has been hypothesized as a risk factor for obesity. In this study, we investigated the association between current shift work and body mass index (BMI) among female nurses in Korea. The relationship between duration of shift work and BMI of the participants was also evaluated.
  
  
  METHODS
  This cross-sectional survey evaluated participants in the Korean Nurses' Survey, conducted from October to December 2011, using web-based self-administered questionnaires. A total of 9,989 nurses were included among 10,000 who registered on the survey web site (5,287 shift workers and 4,702 non-shift workers). Current shift workers were divided into tertiles of shift work duration (0.08-3.00 years, n = 1,732; 3.08-6.75 years, n = 1,731; and 6.83-38.00 years, n = 1,686). The BMI thresholds of overweight and obesity were ≥23 kg/m² and ≥25 kg/m², respectively. Data were analyzed using SPSS software.
  
  
  RESULTS
  Mean participant age was 33.2 ± 8.6 years and the mean BMI was 20.9 ± 2.5 kg/m². There were statistically significant differences in current smoking status, regular drinking habit, dietary habits, regular exercise, sleep problems and self-perceived health status according to duration of shift work. The overall prevalence of overweight/obesity (18.6%) and obesity (7.4%) increased significantly as shift work duration increased from the lowest to highest tertile (P for trend <0.001). Multivariate logistic regression analysis revealed no association between current shift work and BMI. However, after adjusting for potential confounders, the participants with the longest duration of shift work were 1.63 (95% CI, 1.22-2.17) times more likely to be overweight or obese than those with the shortest duration. There was a significant positive association between obesity and shift work duration in the unadjusted analysis; however, it was attenuated and no longer significant in the multivariate model.
  
  
  CONCLUSIONS
  The duration of shift work was positively associated with prevalence of overweight/obesity in nurses in Korea. Although these findings need to be confirmed in prospective studies, they suggest that special attention should be paid to female nurses with a long duration of shift work.
authors.forename: Min-Ju
authors.initials: MJ
authors.lastname: Kim
authors.forename: Kuk-Hui
authors.initials: KH
authors.lastname: Son
authors.affiliation: Division of Cardiovascular and Rare Diseases, Center for Biomedical Science, National Institute of Health, Chungbuk, Korea. mdhypark@gmail.com.
authors.forename: Hyun-Young
authors.initials: HY
authors.lastname: Park
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Choi
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Yoon
authors.forename: Hea-Young
authors.initials: HY
authors.lastname: Lee
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Cho
authors.forename: Myeong-Chan
authors.initials: MC
authors.lastname: Cho
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D009726:Nurses / Q000706:statistics & numerical data*; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology; D050177:Overweight / Q000453:epidemiology / Q000209:etiology; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014940:Work Schedule Tolerance