title: Reliability and validity of the Severity of Dependence Scale in a Chinese sample of treatment-seeking ketamine users.
abstract: OBJECTIVE
  Despite growing popularity of ketamine misuse in Asia, there is a lack of a validated instrument to measure the severity of ketamine dependence. Psychometric properties of Chinese Severity of Dependence Scale for ketamine (C-SDS-K) were examined in a sample of treatment-seeking ketamine users in Hong Kong.
  
  
  METHODS
  A total of 80 treatment-seeking ketamine users were recruited from 3 treatment centres. The C-SDS-K was administered to assess their severity of dependence on ketamine in the previous month. The diagnosis of their ketamine misuse as per the DSM-IV criteria, and the count of dependence criteria fulfilled in the previous month were determined by the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I).
  
  
  RESULTS
  The C-SDS-K showed high internal consistency (α = 0.74) and test-retest reliability (intraclass correlation coefficient = 0.95). Total score of C-SDS-K correlated positively with frequency (rs = 0.73, p < 0.001) and dose (rs = 0.89, p < 0.001) of ketamine use per week in the previous month, duration of regular ketamine use (rs = 0.28, p = 0.01), and the count of DSM-IV ketamine dependence criteria met in the previous month (rs = 0.84, p < 0.001). All items loaded strongly on a single factor (factor loading ≥ 0.60) in principal component analysis.
  
  
  CONCLUSIONS
  The findings support SDS as a reliable and valid tool for measuring the severity of dependence in the treatment-seeking population of Chinese ketamine users.
authors.affiliation: Alcohol and Drug Dependence Unit, Castle Peak Hospital, Hong Kong SAR, China.
authors.forename: C K
authors.initials: CK
authors.lastname: Tung
authors.affiliation: Alcohol and Drug Dependence Unit, Castle Peak Hospital, Hong Kong SAR, China.
authors.forename: S W
authors.initials: SW
authors.lastname: Yeung
authors.affiliation: Alcohol and Drug Dependence Unit, Castle Peak Hospital, Hong Kong SAR, China.
authors.forename: T P
authors.initials: TP
authors.lastname: Chiang
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, United States.
authors.forename: K
authors.initials: K
authors.lastname: Xu
authors.affiliation: Alcohol and Drug Dependence Unit, Castle Peak Hospital, Hong Kong SAR, China.
authors.forename: M
authors.initials: M
authors.lastname: Lam
mesh_terms: D000293:Adolescent; D000328:Adult; D000700:Analgesics; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007649:Ketamine; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D000700:Analgesics; D007649:Ketamine
keywords: Ketamine; Substance-related disorders; Treatment outcome