title: Multiple roles and all-cause mortality: the Japan Collaborative Cohort Study.
abstract: BACKGROUND
  Two contrasting perspectives on the effects of multiple roles; the 'role overload hypothesis' and the 'role enhancement model', have been proposed to predict variations in health. The aim of this study was to evaluate the impact of multiple roles on all-cause mortality in Japan where gender roles are currently changing.
  
  
  METHODS
  A total of 76,758 individuals from the Japan Collaborative Cohort Study were followed for an average of 15.7 years. Hazard ratios (HRs) with 95% confidence intervals were calculated from proportional hazard models to estimate the risk of all-cause mortality according to multiple roles (spouse, parent and worker, and combinations of these roles).
  
  
  RESULTS
  After adjusting for potential confounding factors, the risks of all-cause mortality were elevated among men and women without a role. The number of roles was also associated with all-cause mortality risk, showing the highest risk values among those with no roles compared with those with triple roles (HR: 1.66 in men and 1.78 in women). The impact of the lack of a role was generally greater in men than in women and also in the middle-aged than in the elderly.
  
  
  CONCLUSIONS
  A beneficial effect of multiple roles was suggested among Japanese. The fewer roles they had, the higher all-cause mortality risks were observed. The risk values of those with fewer roles were generally higher in men than in women and also in the middle-aged than in the elderly, partially explained by greater role overload in middle-aged women than other groups in Japan.
authors.affiliation: Department of Public Health, Aichi Medical University School of Medicine, Aichi, Japan. aa@aichi-med-u.ac.jp
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.forename: Ai
authors.initials: A
authors.lastname: Ikeda
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Fujino
authors.forename: Koji
authors.initials: K
authors.lastname: Tamakoshi
authors.forename: Hisoyasu
authors.initials: H
authors.lastname: Iso
mesh_terms: D000328:Adult; D000368:Aged; D002423:Cause of Death; D015331:Cohort Studies; D016001:Confidence Intervals; D004651:Employment; D005191:Family Characteristics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009026:Mortality; D010290:Parents; D016016:Proportional Hazards Models; D012307:Risk Factors; D012380:Role; D017678:Sex Distribution; D012959:Socioeconomic Factors; D018454:Spouses; D011795:Surveys and Questionnaires; D014937:Work