Guidelines for ATC classification and DDD assignment - WHOCC

linked to each medicinal product on the package level. National registries should
as a minimum include the following variables:
• Unique identifier (registration number)
• Medicinal product name (brand name/trademark)
• Pharmaceutical form
• Strength
• Pack size
• ATC code
• Active ingredient(s)
• DDD
• Route of administration
• Number of DDDs in the pack
For an extended list of recommended variables to be included in a national
medicinal product registry, see EURO-MED-STAT
(http://www.euromedstat.cnr.it/).
It is of vital importance that the ATC code is correctly linked to each medicinal
product package. The number of DDDs per package should be calculated for each
medicinal product package.
Good procedures for updating national registries with new ATC codes/DDDs and
alterations should be established. It is recommended that the responsibility for
quality assurance and validation of national registries is allocated to a national body
in each country. This work should be performed by competent persons with good
knowledge of the ATC/DDD methodology.
An updated version of the ATC/DDD Index is issued in January each year. To be
able to compare drug utilization data from different countries and time periods, it is
essential to know which ATC codes and DDDs are used. A minimum number of
changes in the ATC codes and DDDs are made annually. Thus, it is important to
give proper references to the ATC/DDD version used when presenting drug
consumption figures.
A publication entitled
“Introduction to Drug Utilization Research” is available from WHO Geneva.
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