title: Distribution of Total Depressive Symptoms Scores and Each Depressive Symptom Item in a Sample of Japanese Employees.
abstract: BACKGROUND
  In a previous study, we reported that the distribution of total depressive symptoms scores according to the Center for Epidemiologic Studies Depression Scale (CES-D) in a general population is stable throughout middle adulthood and follows an exponential pattern except for at the lowest end of the symptom score. Furthermore, the individual distributions of 16 negative symptom items of the CES-D exhibit a common mathematical pattern. To confirm the reproducibility of these findings, we investigated the distribution of total depressive symptoms scores and 16 negative symptom items in a sample of Japanese employees.
  
  
  METHODS
  We analyzed 7624 employees aged 20-59 years who had participated in the Northern Japan Occupational Health Promotion Centers Collaboration Study for Mental Health. Depressive symptoms were assessed using the CES-D. The CES-D contains 20 items, each of which is scored in four grades: "rarely," "some," "much," and "most of the time." The descriptive statistics and frequency curves of the distributions were then compared according to age group.
  
  
  RESULTS
  The distribution of total depressive symptoms scores appeared to be stable from 30-59 years. The right tail of the distribution for ages 30-59 years exhibited a linear pattern with a log-normal scale. The distributions of the 16 individual negative symptom items of the CES-D exhibited a common mathematical pattern which displayed different distributions with a boundary at "some." The distributions of the 16 negative symptom items from "some" to "most" followed a linear pattern with a log-normal scale.
  
  
  CONCLUSIONS
  The distributions of the total depressive symptoms scores and individual negative symptom items in a Japanese occupational setting show the same patterns as those observed in a general population. These results show that the specific mathematical patterns of the distributions of total depressive symptoms scores and individual negative symptom items can be reproduced in an occupational population.
authors.affiliation: Department of Mental Health, Panasonic Health Center, Tokyo, Japan.|Department of Drug Evaluation and Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Tomitaka
authors.affiliation: Department of Drug Evaluation and Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Kawasaki
authors.affiliation: Department of Drug Evaluation and Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Ide
authors.affiliation: Department of Drug Evaluation and Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Hokkaido Occupational Health Promotion Center, Labor Health and Welfare, Sapporo, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Miyake
authors.forename: Toshiaki A
authors.initials: TA
authors.lastname: Furukawa
authors.affiliation: Department of Mental Health, Panasonic Health Center, Tokyo, Japan.|Department of Health Promotion and Human Behavior, Kyoto University Graduate School of Medicine/School of Public Health, Kyoto, Japan.
authors.forename: Toshiaki A
authors.initials: TA
authors.lastname: Furukaw
mesh_terms: D000328:Adult; D003863:Depression / Q000523:psychology*; D004651:Employment; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D016272:Occupational Health; D011569:Psychiatric Status Rating Scales; D011795:Surveys and Questionnaires; D055815:Young Adult
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