During its first three years of existence, the EMCDDA gave priority to defining and using instruments related to the demand for drugs and reducing that demand. In this context, it launched a comparative analysis of drugs and of intervention methods and measures applied by the EU Member States and European institutions. During this time, high priority was given to the field of epidemiology (the study of the incidence of, geographic distribution of and trends in drug use and its consequences). In addition to the Annual Report on the State of the Drugs Problem in the European Union, the Monitoring Centre also produced specialised scientific reports, identified key indicators of drug use to be implemented at European level and updated its documentation on epidemiological research. During its first three years, the EMCDDA worked to synthesise, harmonise and evaluate the different studies undertaken and the information gathered on initiatives taken by the Member States and the European Union prior to the Centre's creation. It undertook a high-level study to identify the information required by users (including policy-makers and practitioners in the drugs field), and to reveal existing information sources in such a way as to make them progressively comparable and to identify the gap that remained to be filled.