The current study extends prior work on IRT analyses to DSM-IV cannabis abuse and dependence and has important implications for the DSM-V. The results do not support the abuse and dependence distinction, nor the prodromal relationship of abuse to dependence. Our findings also indicate that a dimensional representation would provide a useful addition to the current diagnostic classification of cannabis use disorder. The results of these IRT analyses can also be used to create a continuous dimensional scale of cannabis use disorder by weighting each DSM-IV diagnostic criterion by its associated severity and/or discrimination parameters. These scales can be used to express the severity of cannabis use disorder in the general population, to assess outcome in clinical trials, or to measure changes in severity of cannabis use disorder in longitudinal studies. Future research is critically needed to identify psychometrically optimal consumption criteria for all drugs to be included in the DSM-V. This work promises to improve immensely the diagnostic utility of substance use disorders in the DSM-V, but additionally to provide for the development of psychometrically sound measures of severity
