Substance Dependence Severity Scale: reliability and validity for ICD-10 substance use disorders

The Substance Dependence Severity Scale (SDSS) is a semistructured interview that assesses the severity of the DSM-IV diagnoses of dependence and abuse and the ICD-10 diagnoses of substance dependence and harmful use across a wide range of substances. Previous research has demonstrated that the SDSS' DSM-IV dependence scales are reliable and valid indicators of diagnostic severity. However, the ICD-10 scales have not been psychometrically tested. This study investigated the test-retest reliability, internal consistency, diagnostic concordance, and concurrent validity of the SDSS' ICD-10 dependence and harmful use scales in 180 (112 male and 68 female) treated substance users. Test-retest reliabilities for the ICD-10 dependence scales ranged from good to excellent for alcohol, cocaine, heroin, and cannabis. Test-retest reliabilities for the SDSS' ICD-10 harmful use scales were in the good range for alcohol, cocaine, and heroin and the poor to fair range for cannabis. Internal consistency, diagnostic concordance, and concurrent validity results were comparable to the test-retest findings. These results support the use of the SDSS for assessing the severity of the ICD-10 dependence and harmful use diagnoses.