title: Effect of Long Working Hours on Self-reported Hypertension among Middle-aged and Older Wage Workers.
abstract: OBJECTIVE
  Many studies have reported an association between overwork and hypertension. However, research on the health effects of long working hours has yielded inconclusive results. The objective of this study was to identify an association between overtime work and hypertension in wage workers 45 years and over of age using prospective data.
  
  
  METHODS
  Wage workers in Korea aged 45 years and over were selected for inclusion in this study from among 10,254 subjects from the Korean Longitudinal Study of Ageing. Workers with baseline hypertension and those with other major diseases were excluded. In the end, a total of 1,079 subjects were included. A Cox proportional hazards model was used to calculate hazard ratios and adjust for baseline characteristics such as sex, age, education, income, occupation, form of employment, body mass index, alcohol habit, smoking habit, regular exercise, and number of working days per week. Additional models were used to calculate hazard ratios after gender stratification.
  
  
  RESULTS
  Among the 1,079 subjects, 85 workers were diagnosed with hypertension during 3974.2 person-months. The average number of working hours per week for all subjects was 47.68. The proportion of overtime workers was 61.0% (cutoff, 40 h per week). Compared with those working 40 h and less per week, the hazard ratio of subjects in the final model, which adjusted for all selected variables, working 41-50 h per week was 2.20 (95% confidence interval [CI], 1.19-4.06), that of subjects working 51-60 h per week was 2.40 (95% CI, 1.07-5.39), and that of subjects working 61 h and over per week was 2.87 (95% CI, 1.33-6.20). In gender stratification models, the hazard ratio of the females tended to be higher than that of the males.
  
  
  CONCLUSIONS
  As the number of working hours per week increased, the hazard ratio for diagnosis of hypertension significantly increased. This result suggests a positive association between overtime work and the risk of hypertension.
authors: Department of Occupational and Environmental Medicine, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Gwanak-ro 1, Seoul 151-742, Gwanak-gu, Republic of Korea.
authors: Dong Hyun
authors: DH
authors: Yoo
authors: Department of Preventive Medicine, School of Medicine, Seoul National University, Daehakro 103, Seoul 110-799, Jongno-gu, Republic of Korea.
authors: Mo-Yeol
authors: MY
authors: Kang
authors: Department of Occupational and Environmental Medicine, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Gwanak-ro 1, Seoul 151-742, Gwanak-gu, Republic of Korea.
authors: Domyung
authors: D
authors: Paek
authors: Department of Occupational and Environmental Medicine, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Gwanak-ro 1, Seoul 151-742, Gwanak-gu, Republic of Korea.
authors: Bokki
authors: B
authors: Min
authors: Department of Occupational and Environmental Medicine, Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Gwanak-ro 1, Seoul 151-742, Gwanak-gu, Republic of Korea.
authors: Sung-Il
authors: SI
authors: Cho
keywords: Hypertension; Long working hours; Self-reported hypertension; Wage workers