title: Psychometric validation of the Leeds Dependence Questionnaire (LDQ) in a young adult clinical sample.
abstract: OBJECTIVE
  Measures of substance dependence severity that are both clinically efficient and sensitive to change can facilitate assessment of clinical innovation necessary for improving current evidence-based practices. The Leeds Dependence Questionnaire (LDQ) is a 10-item, continuous, self-report measure of dependence that is not specific to any particular substance and has shown promise in preliminary psychometric research. The present study investigates its psychometric properties in a large clinical sample of young adults.
  
  
  METHODS
  Young adults (N=300) were enrolled in a naturalistic treatment process and outcome study of residential substance dependence treatment (mean age 20.4 [1.6], range 18-25; 27% female; 95% White). Dependence severity by demographic and diagnostic groupings, factor structure and internal consistency, and criterion- and construct-related validity were examined.
  
  
  RESULTS
  Dependence severity in this cohort of youth overall was high (M=18.65 [8.65]). LDQ scores were highest among opiate and stimulant users, and there was a trend for higher scores among women compared to men (t=1.869, p=.063). Factor analysis using a robust alpha factoring extraction revealed a single factor accounting for 63% of the variance in reported dependence severity. The internal consistency was also very high (alpha=.93). Concurrent and convergent validity with dependence criteria, substance use frequency, and general symptom severity, respectively, were also acceptable.
  
  
  CONCLUSIONS
  The LDQ shows considerable promise as a brief, psychometrically sound, measure of substance dependence useful across a variety of substances, that has clinical and research utility. This study supports its use among young adults.
authors.affiliation: Center for Addiction Medicine, Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, United States. jkelly11@partners.org
authors.forename: John F
authors.initials: JF
authors.lastname: Kelly
authors.forename: Molly
authors.initials: M
authors.lastname: Magill
authors.forename: Valerie
authors.initials: V
authors.lastname: Slaymaker
authors.forename: Christopher
authors.initials: C
authors.lastname: Kahler
mesh_terms: D000293:Adolescent; D000328:Adult; D016739:Behavior, Addictive / Q000175:diagnosis* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D011594:Psychometrics; D015203:Reproducibility of Results; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000523:psychology; D011795:Surveys and Questionnaires / Q000592:standards*; D014481:United States; D055815:Young Adult