Postal address:
Norwegian Institute of Public Health
WHO Collaborating Centre for Drug Statistics Methodology
Postboks 222 Sk°yen
0213 Oslo

Visiting/delivery address:
Myrens verksted 6H
0473 Oslo

Tel:  +47 21 07 81 60


The field of Drug Utilization Research (DUR) began attracting attention in the 1960’s. A WHO symposium in 1969 highlighted the need for an internationally accepted classification system for drug utilization studies. As a result the Drug Utilization Research Group (DURG) was established and entrusted with the development of internationally applicable methods for DUR.  Inspired by this interest, the Anatomical Therapeutic Chemical (ATC) classification was developed in Norway as a modification and extension of the European Pharmaceutical Market Research Association (EphMRA) classification system.

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) was developed for use in drug utilization studies.

In 1981, the ATC/DDD system was recommended by WHO as the international standard for drug utilization studies, and in 1982 the WHO Collaborating Centre for Drug Statistics Methodology was established and given the responsibility for coordinating the development and use of the ATC/DDD system.  In 1996, the Centre was recognized as a global centre. 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 Headquarter 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: 2018-02-15