[Use of cannabis: screening strategy and evaluation of severity factors].

Cannabis consumption occupies a front place in the field of addictions in France, not only by the levels of consumption but also by the related health harms induced with a growing potentially problematic use of cannabis among young men (14% of those aged 14 to 18 in 2001). Therefore, it is not only an educational problem but also a public health issue. Harmful cannabis use must be systematically researched by history taking on the consumption of tobacco, alcohol and drugs as an integrated part of the patient's social history. The diagnostic of cannabis abuse is made by a clinical evaluation of harmful use, the frequency and quantity of consumption, the search for complications. The practitioner must also evaluate the factors of severity (modalities of consumption and parameters predictive of poor outcome like precocity of first experiences, auto-therapeutic use and the various types of individual and social vulnerability: personality characteristics, psychiatric pathology, family characteristics and social environment). The physician may also be helped by drug screening diagnostic and evaluation instruments like validated autoquestionnaires. Urinary screening can be used especially in public health or forensic medicine fields. Some situational risks must be known while cannabis intoxicated: pregnant women, mentally ill, driving, working. Finally, professionals must know that present situation is very different from what we knew in the seventies and that they have to cope with this fast moving issue.