Determining a diagnostic cut‐off on the Severity of Dependence Scale (SDS) for cocaine dependence

AIM: The study aimed to assess the efficacy of the Severity of Dependence Scale (SDS) as a diagnostic measure of cocaine dependence and determine the cut-off score that best discriminates between the presence and absence of a DSM-IV diagnosis of cocaine dependence. DESIGN: Cross-sectional survey. SETTING: Sydney, Australia. PARTICIPANTS: One hundred and forty-two cocaine users. MEASUREMENTS: The diagnostic performance of the SDS was measured via ROC analysis against DSM-IV diagnoses of cocaine dependence, as measured by the Composite International Diagnostic Interview (CIDI). FINDINGS: ROC analysis revealed the SDS to be a test of high diagnostic utility for the measurement of cocaine dependence. The cut-off point on the SDS at which there is optimal discrimination between the presence and absence of a DSM-IV diagnosis of cocaine dependence was found to be 3 (i.e. a score of 3 or more). CONCLUSIONS: The study statistically validated the utility of the SDS as a diagnostic measure of cocaine dependence and has determined an appropriate cut-off point. The SDS is recommended as a brief screening instrument for cocaine dependence that can be used in addition to more comprehensive measures, such as the CIDI.