Long working hours and risk for hypertension in Japanese male white collar workers.
OBJECTIVE
To evaluate the association of long working hours with the risk for hypertension.


METHODS
A five year prospective cohort study.


METHODS
Work site in Osaka, Japan.


METHODS
941 hypertension free Japanese male white collar workers aged 35-54 years were prospectively examined by serial annual health examinations. Men in whom borderline hypertension and hypertension were found during repeated surveys were defined as incidental cases of borderline hypertension and hypertension.


RESULTS
336 and 88 men developed hypertension above the borderline level and definite hypertension during the 3940 and 4531 person years, respectively. After controlling for potential predictors of hypertension, the relative risk for hypertension above the borderline level, compared with those who worked < 8.0 hours per day, was 0.63 (95% confidence intervals (CI): 0.43, 0.91) for those who worked 10.0-10.9 hours per day and 0.48 (95% CI: 0.31, 0.74) for those who worked > or = 11.0 hours per day. The relative risk for definite hypertension, compared with those who worked < 8.0 hours per day, was 0.33 (95% CI: 0.11, 0.95) for those who worked > or = 11.0 hours per day. The multivariate adjusted slopes of diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) during five years of follow up decreased as working hours per day increased. From the multiple regression analyses, working hours per day remained as an independent negative factor for the slopes of systolic blood pressure, DBP, and MABP.


CONCLUSIONS
These results indicate that long working hours are negatively associated with the risk for hypertension in Japanese male white collar workers.
Nakanishi
N
N
Department of Social and Environmental Medicine, Course of Social Medicine, Osaka University Graduate School of Medicine F2, 2-2 Yamada-oka, Suita-shi, Osaka 565-0871, Japan. noriyuki@pbhel.med.osaka-u.ac.jp
Yoshida
H
H
Nagano
K
K
Kawashimo
H
H
Nakamura
K
K
Tatara
K
K
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D015331:Cohort Studies; D006801:Humans; D006973:Hypertension / Q000209:etiology* / Q000503:physiopathology; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D013315:Stress, Psychological / Q000209:etiology*; D014940:Work Schedule Tolerance