Reliability and Validity of the Spanish Version of the Substance Dependence Severity Scale

Purpose: The purpose of this study was to estimate the reliability and provide evidence for the validity of the Spanish version of the Substance Dependence Severity Scale (SDSS). Methods: A total of 211 substance abusers recruited at a public center that provides treatment for substance-related disorders in an outpatient setting were assessed. Reliability was estimated by Cronbach's α and test-retest. Validity evidence was studied by analyzing the relationships with the European Addiction Severity Index (EuropASI) and Health-Related Quality of Life for Drug Abusers (HRQoLDA). Results: Adequate reliability coefficients were found for the dependence scales of all addressed substances (α = 0.737 to 0.877; test-retest r = 0.796-0.952). Low internal consistency was found for the abuse scales (α = 0.329-0.694), and adequate test-retest coefficients on alcohol, cocaine and heroin (test-retest r = 0.708-0.902). The reliability of the cannabis abuse scales was inadequate. The SDSS scores showed significant relationships with the EuropASI and HRQoLDA dimensions. Conclusions: The psychometric analyses validate the use of the severity of dependence scales. The SDSS abuse scales must be used taking the limitations detected into consideration.