Assessing the Validity and Reliability of the Farsi Version of Inventory Drug-taking Situations

Objective: Inventory Drug-Taking Situations (IDTS) is a universal instrument used to determine high-risk situations resulting in drug abuse. The aim of this study was to translate this questionnaire to Farsi, and to assess its validity and reliability by applying it to Iranian drug users.

Methods: As a psychometric study, 300 drug users participated in a treatment program in National Center of Addiction Studies filled in a version of Inventory of Drug Taking Situations. We assessed face and content validity, internal consistency, and reliability based on the completed questionnaires, using test-retest method and confirmatory factor analysis.

Results: Internal consistency analysis confirmed that all subscales of IDTS were reliable (Cronbach alpha was ranging from 0.7 to 0.81). Analyses indicated that each of the subscales was unifactorial; however, unpleasant emotions had a second eigenvalue that was nearly large enough to be a second factor. Confirmatory factor analysis was used to test the fit of the data to the original version of IDTS. Based on goodness of fit indices, we found that all factors were fitted (χ2/df = 1.43, GFI = 0.98, RMSEA = 0.038). The test-retest reliability was satisfactory(r > 0.6).

Conclusion: The Farsi version of Inventory of Drug Taking Situations was shown to be a valid and reliable instrument to apply in clinical and research settings in Iran.