Guidelines for ATC classification and DDD assignment - WHOCC

In order to include proposals for ATC alterations on the agenda for the Working
Group meetings, they should be forwarded to the Centre before 15 January (March
meeting) and before 15 August (October meeting). These dates should be
considered as a guideline since there might be changes in the meeting dates from
one year to another.
ATC alterations decided at the March meeting (e.g. March 2011) will be included
in the ATC index the following year (i.e. January 2012). ATC alterations decided
at the October meeting of the Working Group (e.g. October 2011) will be included
in the ATC index the year after the following year (i.e. January 2013).
2. Data requirements for submission
When requesting changes to ATC classifications, the data requirements are similar
to the data required for new ATC codes. An important basis for the ATC/DDD
system is to maintain a stable database for drug consumption studies. For this
reason, there need to be compelling reasons for changing ATC codes. It is
therefore important to submit data, which justify the proposed change.
If a change in the main therapeutic use is the reason for the proposed change, the
data submitted should clearly indicate this change (e.g. market research data
showing the percentage use for the different indications in a range of countries).
If new knowledge of pharmacology or mechanism of action is the reason for the
proposed change, relevant evidence should be submitted.
If the proposed change is to establish specific ATC groups for one or more
substances already classified in another group (usually a various group), it is
necessary to submit data that verify that the change is beneficial and represents an
improvement of the ATC classification for presenting drug consumption statistics.
Justifications based on reimbursement, pricing or marketing reasons will not be
considered.
C. Requests for DDD assignment
1. Procedures and timing
All new DDDs are assigned on request from the users. Requests for new DDDs
should be addressed to the WHO Collaborating Centre for Drug Statistics
Methodology. The application form for assignment of new DDDs is shown in
Annex I and copies are available from the Centre (www.whocc.no). Any user may
in principle propose a new DDD (e.g. health authorities, pharmaceutical
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