This is the official classi-fication system of the World Health Organization (WHO). As a general system for the classification of diseases, injuries, causes of death, and related health problems, the ICD is used throughout the world as a common frame of reference for statistical reporting, clinical practice, and education. The ICD is a system of categories to which specific disease entities can be assigned consistently in different parts of the world. Recognizing the growing importance of alcohol and drug misuse, the ninth revision of ICD was published in 1975 (ICD-9), and it introduced the terms dependence and abuse into the international nomenclature. Drug dependence was defined as "a state, psychic and sometimes also physical, resulting from taking a drug, and characterized by behavioural and other responses that always include a compulsion to take the drug on a continuous or periodic basis...