Objectives: We investigated whether the association between shift work and hypertension is independent of weight gain.
Methods: Subjects were 10,173 male employees (9209 daytime workers, 964 three-shift workers; mean follow-up period: 12.7 years). Hypertension was defined as systolic blood pressure 140 mm Hg or more or diastolic blood pressure 90 mm Hg or more. The risk of developing hypertension among shift workers was estimated using a Cox proportional hazards model with adjustment for several factors.
Results: Analysis revealed that “shift work” (hazard ratio [HR]: 1.85; 95% confidence interval [CI]: 1.68, 2.03), “baseline body mass index” (HR: 1.13; 95% CI: 1.12, 1.15), and “increase in body mass index during follow-up” (HR: 1.15; 95% CI: 1.13, 1.17) were significant independent risk factors for hypertension.
Conclusions: Shift work is a significant risk factor for hypertension that is independent of both starting weight and weight gained over years of work.
From the Department of Public Health (Drs Kubo, Fujino, and Matsuda), School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan; Asahi Kasei Chemicals Mizushima Works Health Care Center (Dr Nakamura), Kurashiki, Japan; Asahi Kasei Corporation Nobeoka Office Health Care Center (Drs Kunimoto, Tabata, Tsuchiya, and Kadowaki), Nobeoka, Japan; Asahi Kasei Corporation Moriyama Office (Dr Odoi), Health Care Office, Moriyama, Japan; and Corporate Environmental Safety Health and Quality Assurance (Dr Oyama), Asahi Kasei Corporation, Tokyo, Japan.
Address correspondence to: Tatsuhiko Kubo, MD, PhD, Department of Public Health, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahata-nishi-ku, Kitakyushu, Fukuoka, 807-8555, Japan (firstname.lastname@example.org).
This work was supported by MEXT/JSPS KAKENHI grant number 19790437 and 22590618; and Research Grant for Occupational Health 2007–2008 from the Occupational Health Promotion Foundation, Japan. The authors declare that they have no competing financial interests.
The authors declare no conflicts of interest.