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Key Messages

• The ATC/DDD Classification System is a widely used tool for measuring the use and consumption of drugs.
• The quality of drug utilization reporting should be enhanced, including analytical methods and definitions of appropriate and inappropriate use.
• National authorities and governments should develop, guide and implement policy for the appropriate use of the ATC/DDD Classification System and discourage misuse for drug pricing and reimbursement.

Background

Drug utilization or consumption is measured, according to the WHO, with the ATC/DDD Classification System.  The Anatomical Therapeutic Chemical (ATC) Classification System categorizes the active pharmaceutical ingredient of a drug by its therapeutic use and targeted organ or system, for example, the heart or circulatory system.  Once the drug has been classified and assigned an ATC “code”, a Defined Daily Dose (DDD) must be given in order to accurately measure consumption.  The DDD is the assumed average dose per day for an adult.  The WHO Collaborating Center for Drug Statistics Methodology is responsible for developing and maintaining the System.

The ATC/DDD Classification system is designed to aid governments and researchers in their efforts to determine whether the use of a specific drug is appropriate.  For example, drug utilization research may give national authorities information about a therapeutic class of drugs that is being over-prescribed at a national level.  The resulting information provided by the research could ultimately lead to changes in health policy and increased training efforts for prescribers.  However, in several instances, national authorities are misusing the Classification System where ATC Codes are being utilized for therapeutic reference pricing and DDDs for pricing and reimbursement decisions.