Postal address:
WHO Collaborating Centre for Drug Statistics Methodology
Norwegian Institute of Public Health
P.O.Box 4404 Nydalen
0403 Oslo

Visiting/delivery address:
Marcus Thranes gate 6
0473 Oslo

Tel:  +47 21 07 81 60


The field of drug utilization research has attracted increasing interest since its infancy in the 1960s. At a symposium in Oslo in 1969 entitled The Consumption of Drugs, it was agreed that an internationally accepted classification system for drug consumption studies was needed. At the same symposium the Drug Utilization Research Group (DURG) was established and tasked with the development of internationally applicable methods for drug utilization research.

By modifying and extending the European Pharmaceutical Market Research Association (EphMRA) classification system, Norwegian researchers developed a system known as the Anatomical Therapeutic Chemical (ATC) classification.

In order to measure drug use, it is important to have both a classification system and a unit of measurement. To deal with the objections against traditional units of measurement, a technical unit of measurement called the Defined Daily Dose (DDD) to be used in drug utilisation studies was developed.

The Nordic Council on Medicines (NLN) established in 1975, collaborated with Norwegian researchers to further develop the ATC/DDD system. The NLN published the Nordic Statistics on Medicines using the ATC/DDD methodology for the first time in 1976. Since then the interest in the ATC/DDD system for drug utilisation research has expanded.

In 1981, the WHO Regional Office for Europe recommended the ATC/DDD system for international drug utilization studies. In connection with this, and to make the methodology more widely used, there was a need for a central body responsible for co-ordinating the use of the methodology. The WHO Collaborating Centre for Drug Statistics Methodology was accordingly established in Oslo in 1982. The Centre is now located at the Norwegian Institute of Public Health. The Norwegian government funds the Centre.

In 1996, WHO recognised the need to develop use of the ATC/DDD system as an international standard for drug utilization studies. The Centre was therefore linked directly to WHO Headquarters in Geneva instead of the WHO Regional Office for Europe in Copenhagen. This was seen as important to allow close integration of international drug utilization studies and WHO’s initiatives to achieve universal access to needed drugs and rational use of drugs particularly in developing countries. Access to standardised and validated information on drug use is essential to allow audit of patterns of drug utilization, identification of problems, educational or other interventions and monitoring of the outcomes of the interventions.

When the decision on globalizing the ATC/DDD system was taken, the WHO Division of Drug Management and Policies established the WHO International Working Group for Drug Statistics Methodology. The WHO Collaborating Centre for Drug Statistics Methodology receives expert advice from the Working Group.

Last updated: 2009-11-19