Risk of Hypertension and Impaired Glucose Tolerance among Two and Three Shift Workers

Kubo, Tatsuhikiko

Risk of Hypertension and Impaired Glucose Tolerance among Two and Three Shift Workers

Sunday, 17 August 2014: 4:15 PM

Ballroom D (Dena'ina Center)

Tatsuhikiko Kubo, PhD , University of Occupational and Environmental Health, Kitakyusyu, Japan

Yoshihisa Fujino, PhD , University of Occupational and Environmental Health, Kitakyushu, Japan

Shinya Matsuda, PhD , University of Occupational and Environmental Health, Kitakyushu, Japan

Takehiro Nakamura, MD , Asahi Kasei Corporation, Tokyo, Japan

Masamizu Kunimoto, MD , Asahi Kasei Corporation, Tokyo, Japan

Koji Kadowaki, MD , Asahi Kasei Corporation, Tokyo, Japan

Hidetoshi Tabata, MD , Asahi Kasei Corporation, Tokyo, Japan

Takuto Tsuchiya, MD , Asahi Kasei Corporation, Tokyo, Japan

Haruka Odoi, MD , Asahi Kasei Corporation, Tokyo, Japan

Ichiro Oyama, MD , Asahi Kasei Corporation, Tokyo, Japan

INTRODUCTION: We investigated the effect of two types of shift work schedule (two shift work and three shift work) on risk of hypertension and impaired glucose tolerance (IGT) respectively.

METHODS: The cohort was established based on a health care database system belonging to a manufacturing corporation in Japan. The study database contains data regarding annual health check-ups and work schedules for every worker in Japan since 1981. Subjects for hypertension risk analysis were 9,012 daytime workers, 936 three shift workers and 399 two shift workers. Systolic blood pressure >=140mmHg or diastolic blood pressure >=90mmHg were treated as case definition. Besides this analysis, 5,304 daytime workers, 454 three shift workers and 255 two shift workers were selected for the analysis for IGT risk; case definition for IGT was HbA1c≥5.9%. All those workers were male, free from the outcome diseases at the baseline, and whose work schedules were consistent during the follow-up period. The Cox proportional hazards model was used to estimate the risk, with adjustments for age, smoking, alcohol drinking, and leisure time physical activity and body mass index (BMI).

RESULTS: Compared to daytime workers, the hypertension risk was more prevalent among three-shift workers (hazard ratio (HR) =2.01, 95% Confidence interval (CI): 1.83-2.21) than two-shift workers (HR=1.50, 95%CI: 1.31, 1.73). On the other hand, the IGT risk was more prevalent among two-shift workers (HR =2.80, 95% CI: 2.27-3.45) than three-shift workers (HR=1.41, 95%CI: 1.13, 1.76).

CONCLUSIONS: Health impact of shift working was different between the work schedules. Also, the relative magnitude of the impact of the work schedules depended on the outcomes measures. That suggests there is no “ultimate shift work schedule”.