title: Occupational sitting time and risk of all-cause mortality among Japanese workers.
abstract: OBJECTIVE
  Prolonged sitting is a health risk for cardiovascular diseases and all-cause mortality, independent of moderate-to-vigorous physical activity. Epidemiological evaluation of occupational sitting has received little attention, even though it may have a potential impact on workers' health. We prospectively examined the association between occupational sitting time and all-cause mortality.
  
  
  METHODS
  Community-dwelling, Japanese workers aged 50-74 years who responded to a questionnaire in 2000-2003 were followed for all-cause mortality through 2011. Cox proportional hazard models were employed to calculate hazard ratios (HR) of all-cause mortality among middle (1- to <3 hours/day) or longer (≥3 hours/day) occupationally sedentary subjects by gender or types of engaging industry ("primary industry" and "secondary or tertiary industry").
  
  
  RESULTS
  During 368,120 person-years of follow-up (average follow-up period, 10.1 years) for the 36,516 subjects, 2209 deaths were identified. Among workers in primary industry, longer duration of occupational sitting was significantly or marginally associated with higher mortality [HR 1.23, 95% confidence interval (95% CI) 1.00-1.51 among men; HR 1.34, 95% CI 0.97-1.84 among women]. No associations were found among secondary or tertiary industry workers (men: HR 0.87, 95% CI 0.75-1.01; women: HR 1.03, 95% CI 0.77-1.39).
  
  
  CONCLUSIONS
  Occupational sitting time increased all-cause mortality among primary industry workers, however similar relationships were not observed for secondary-tertiary workers. Future studies are needed to confirm detailed dose-response relationships by using objective measures. In addition, studies using cause-specific mortality data would be important to clarify the physiological underlying mechanism.
authors.affiliation: Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan. inoue@tokyo-med.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Inoue
authors.forename: Yuko
authors.initials: Y
authors.lastname: Odagiri
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Norie
authors.initials: N
authors.lastname: Sawada
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000367:Age Factors; D000368:Aged; D002423:Cause of Death; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D007221:Industry / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009026:Mortality; D016272:Occupational Health; D009790:Occupations / Q000706:statistics & numerical data; D011187:Posture; D016016:Proportional Hazards Models; D012307:Risk Factors; D057185:Sedentary Behavior; D012737:Sex Factors; D013997:Time Factors; D017132:Workplace / Q000706:statistics & numerical data*