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.

Method: 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.