Association between duration of daily VDT use and subjective symptoms.
BACKGROUND
Although visual display terminal (VDT) work has become a common task among office workers, surveys which would help to determine the allowable duration of daily VDT use are limited.


METHODS
We investigated more than 25,000 workers three times over a 3-year period using a self-administered questionnaire. Three factors, namely mental, physical and sleep-related symptoms, were extracted by factor analysis. Adjusted means of each factor score were compared with the duration of daily VDT use by general linear model.


RESULTS
Physical symptoms score became higher with increasing duration of daily VDT use without a threshold effect. Mental and sleep-related symptom scores of the workers using VDT for more 5 hr/day were significantly higher than that of the groups using VDT for >1, 1-3, and 3-5 hr/day.


CONCLUSIONS
Duration of daily VDT use was linearly related to the physical symptom score, and was non-linearly related to mental and sleep-related symptom score with a threshold effect of 5 hr/day.
Nakazawa
Tetsuya
T
Department of Occupational and Environmental Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan. ookubo@med.m.chiba-u.ac.jp
Okubo
Yasushi
Y
Suwazono
Yasushi
Y
Kobayashi
Etsuko
E
Komine
Shingo
S
Kato
Norihisa
N
Nogawa
Koji
K
D000328:Adult; D018771:Arthralgia / Q000209:etiology; D001248:Asthenopia / Q000209:etiology; D016288:Computer Terminals; D005221:Fatigue / Q000209:etiology; D006261:Headache / Q000209:etiology; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D001523:Mental Disorders / Q000209:etiology; D008875:Middle Aged; D009784:Occupational Diseases / Q000150:complications* / Q000209:etiology* / Q000523:psychology; D020069:Shoulder Pain / Q000209:etiology; D007319:Sleep Initiation and Maintenance Disorders / Q000209:etiology; D011795:Surveys and Questionnaires; D013997:Time Factors