An item response theory modeling of alcohol and marijuana dependences: A National Drug Abuse Treatment Clinical Trials Network study.

This study aimed to examine psychometric properties of the diagnostics criteria for alcohol and marijuana dependences in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), among 462 alcohol users and 311 marijuana users enrolled in two multisite trials of the National Drug Abuse Treatment Clinical Trials Network (CTN-0006 and -0007, Motivational Incentives for Enhanced Drug Abuse Recovery, Drug Free/Methadone Clinics). Diagnostic questions were assessed by the DSM-IV Checklist, and data were analyzed by the item response theory and the multiple indicators-multiple causes method procedures. Criterion symptoms of alcohol and marijuana dependencies exhibited a high level of internal consistency. All individual symptoms showed good discrimination in distinguishing alcohol or marijuana users between high and low severity levels of the continuum. In both groups, “withdrawal” appeared to measure the most severe symptoms of the dependence continuum. There was little evidence of measurement nonequivalence in assessing symptoms of dependence by gender, age, race/ethnicity, and educational level. These findings highlight the clinical utility of the DSM-IV checklist in assessing alcohol- and marijuana dependence syndromes among treatment-seeking substance users. Additionally, the consistent association between severity of dependence and withdrawal supports the DSM-IV subtyping of “with or without physiological features” and this item should continue to have a significant role in treatment planning and patient placement criteria.

Supported by the Duke Clinical Research Institute (CTN DSC 1).

Related protocols: CTN-0006, CTN-0007