title: Development of a Japanese version of the Somatic Symptom Scale-8: Psychometric validity and internal consistency.
abstract: We aimed to psychometrically validate the Japanese version of the Somatic Symptom Scale-8 (SSS-8) in Japanese individuals.
  
  
  
  Data were collected from Japanese individuals aged 20-64years, who were recruited online, in February 2015. The scale reliability and validity were analyzed.
  
  
  
  Data from 52,353 individuals were analyzed. Cronbach's alpha for the assessment of internal consistency reliability was 0.86 for the total score. The concurrent validity results showed strong correlations with three domains of the Profile of Mood States-Brief form (ρ=0.51-0.61) and the EuroQol 5 Dimension (ρ=-0.54). The known-group validity results indicated a linear trend in the severity of depression stratified using the Patient Health Questionnaire-2 (Jonckheere-Terpstra test, p<0.001). Regarding convergent and discriminant validities, all items correlated most strongly with their own domains (coefficients≥0.5), except for one item (headaches). Scores on perceived stress, pain, and general health differed across five SSS-8 severity groups (Steel-Dwass test, p<0.001), expect for one group pair in health.
  
  
  
  The Japanese version of the SSS-8 was valid with good internal consistency. This questionnaire could help detect somatic symptom burdens of chronic and severe musculoskeletal pain for primary prevention.
authors.affiliation: Department of Medical Research and Management for Musculoskeletal Pain, 22nd Century Medical and Research Center, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan. Electronic address: kohart801@gmail.com.
authors.forename: Ko
authors.initials: K
authors.lastname: Matsudaira
authors.affiliation: Department of Medical Research and Management for Musculoskeletal Pain, 22nd Century Medical and Research Center, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oka
authors.affiliation: Clinical Study Support, Inc., Daiei Bldg., 2F, 1-11-20 Nishiki, Naka-ku, Nagoya 460-0003, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Kawaguchi
authors.affiliation: Department of Psychosomatic Internal Medicine, Sanno Hospital, International University of Health and Welfare, 8-10-16 Akasaka, Minato-ku, Tokyo 107-0052, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Department of Behavioral Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryo, Aoba, Sendai 980-8575, Japan; Department of Psychosomatic Medicine, Tohoku University Hospital, 1-1 Seiryo, Aoba, Sendai 980-8574, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Fukudo
authors.affiliation: Hashizume Clinic, 101, 3-4-5 Miyakojimanakadori, Miyakojima, Osaka 534-0022, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hashizume
authors.affiliation: Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Gebäude O25, 20246 Hamburg, Germany; Department of Psychosomatic Medicine and Psychotherapy, Schön Clinic Hamburg Eilbek, Dehnhaide 120, 22081 Hamburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Löwe
mesh_terms: D000328:Adult; D001007:Anxiety / Q000175:diagnosis*; D003863:Depression / Q000175:diagnosis*; D005221:Fatigue / Q000175:diagnosis*; D005260:Female; D006304:Health Status; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis*; D011569:Psychiatric Status Rating Scales / Q000592:standards*; D011594:Psychometrics / Q000295:instrumentation*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult
keywords: Japanese version; Psychometric validation; Reliability; Somatic Symptom Scale-8; Somatic symptom burden