Objective: The present study aims to examine the validity and reliability of the Thai version of the Missouri Assessment of Genetics Interview for Children [Th-MAGIC] for diagnosis of substance use disorder (alcohol use and abuse/dependence and street drugs sections) in children aged 13 to 17 years.

Materials and Methods: The English version of the MAGIC for diagnosing substance use disorder in adolescent was translated into the Thai language and back-translated. The Th-MAGIC’s content validity was tested. Thirty participants diagnosed with substance use disorders by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision and 30 controls participants were interviewed with Th-MAGIC by a trained interviewer. Afterwards, the concurrent validity and inter-rater reliability were analyzed.

Results: To test the internal consistency, Cronbach’s alpha coefficient for the alcohol-use section and the street drugs section were 0.93 and 0.55, respectively. The sensitivity and specificity of alcohol use section were 86.7% and 100%, respectively. The sensitivity and specificity of street drugs section were 96.7% and 100%, respectively. The kappa coefficient of interrater reliability of alcohol use section was 0.93 and of the street drugs section was 0.94.

Conclusion: The Th-MAGIC for diagnosis of substance use disorder in children age 13 to 17 has a good content and concurrent validity and inter-rater reliability. The results indicated that the Th-MAGIC can be used as a semi-structured interview for identifying substance use problems in adolescence.

Keywords: Validity, Reliability, Th-MAGIC, Substance use disorder