The current data are unable to address the important question of predictive validity or utility of the multi-substance dependence construct. Future studies should examine whether issues such as clinical course and treatment outcomes may be informed by consistent versus inconsistent patterns of involvement across multiple substances. [44,45] The finding of measurement invariance across sampling schemes supports the assumption that DSM criteria are psychometrically equally appropriate for describing substance dependence in epidemiological and clinical samples. Although sample means vary, the measurement properties of DSM-IV substance dependence criteria remain fundamentally the same.
