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Heroin Addiction and Related Clinical Problems: 2012, 14, 2 (pages: 19 - 34)

The Opiate Treatment Index (OTI) clinical interview: New evidence of reliability and validity

González-Saiz F., García-Valderrama T.

Summary: The Opiate Treatment Index (OTI) is a semistructured clinical interview designed by Shane Darke et al., to measure self-reported treatment outcomes of opioid users. It consists of six independent outcome domains. The domains chosen to reflect the dimensions of treatment outcomes were: Drug use, HIV Risk-taking Behaviour, Social Functioning, Criminality, Health, and Psychological Adjustment. The aim of this work is to analyze the internal structure and reliability of the Spanish version of this instrument, as well as to contribute evidence of its concurrent validity with regard to measures of global functioning such as the Global Assessment of Functioning Scale (GAF) of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). The study was carried out with a total sample of 105 patients with substance dependence who were being treated in two centres for drug addictions. Test-retest and inter-rater reliability were both very high (with mean intraclass correlation coefficient [ICC] values for the two scores of .89 and .88, respectively). The internal consistency values were generally moderately high, and similar to those observed by other authors in comparable studies. Principal component analysis (PCA) of each one of the OTI scales reveals structures made up of several factors. The differences between this and other studies and the practical applications of this well-known instrument are discussed.