Assessment of cannabis use disorders: a systematic review of screening and diagnostic instruments

Background. Cannabis use and misuse have become a public health problem. There is a need for reliable screening and assessment tools to identify harmful cannabis use at an early stage. We conducted a systematic review of published instruments used to screen and assess cannabis use disorders. Method. We included papers published until January 2013 from seven different databases, following the PRISMA guidelines and a predetermined set of criteria for article selection. Only tools including a quantification of cannabis use and/or a measurement of the severity of dependence were considered. Results. We identified 34 studies, of which 25 included instruments that met our inclusion criteria: 10 scales to assess cannabis use disorders, seven structured interviews, and eight tools to quantify cannabis use. Both cannabis and substance use scales showed good reliability and were validated in specific populations. Structured interviews were also reliable and showed good validity parameters. Common limitations were inadequate time-frames for screening, lack of brevity, undemonstrated validity for some populations (e.g. psychiatric patients, female gender, adolescents), and lack of relevant information that would enable routine use (e.g. risky use, regular users). Instruments to quantify consumption did not measure grams of the psychoactive compounds, which hampered comparability among different countries or regions where tetrahydrocannabinol concentrations may differ. Conclusions. Current instruments available for assessing cannabis use disorders need to be further improved. A standard cannabis unit should be studied and existing instruments should be adapted to this standard unit in order to improve cannabis use assessment.