Cumulative overview of all DDD alterations performed in the period 2005 to 2020. The year changed is when the alterations were implemented in the ATC/DDD Index. Please note that a DDD may have changed more than once for some ATC codes. The ATC codes are current codes. For substances where the DDD is changed twice the new DDD which is not according to the current value is marked with an asterisk (*).
In 1996, WHO recognized the need to develop the 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 standardized 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.