(044) Assigning Defined Daily Doses (DDD) to Anatomical-Therapeutical-Chemical (ATC) codes that were not addressed by the World Health Organization (WHO): the example of antineoplastics and immunomodulating agents

Publication Number: 707

Background: The ATC/DDD system was developed by WHO to monitor and compare drug use at national and international level. However, WHO does not assign a DDD to all ATC: for some ATC codes the relevant DDD has to be assigned possibly at national level following WHO guidelines, while for topical products, sera, vaccines, antineoplastic agents, allergen extracts, general and local anesthetics and contrast media guidelines for DDD assignment are missing as well. In 2021, the Italian working group on DDD (ITA-wg-DDD) was set with the aim of defining missing DDDs.

Objectives: To report the ITA-wg-DDD experience on the assignment of DDD to the ATC codes of group L (antineoplastics and immunomodulating agents).

Methods: In December 2021, a list of 69 ATC L codes without an official DDD assigned by WHO was identified among medicines marketed in Italy and reimbursed by National Healthcare Service. For DDD assignment, ITA-wg-DDD adopted general criteria from WHO guidelines, information from summaries of product characteristics and available knowledge on the real-world utilization of drugs of interest. Whenever such criteria were not deemed appropriate, new criteria were defined by ITA-wg-DDD.

Results: A DDD was assigned to each one of the 69 ATC L codes. ITA-wg-DDD defined 3 new criteria for drugs whose administration is based on: 1) weight and/or body surface (criterium: maintenance daily dose for the main indication in adults of 70 kg of weight and 170 cm of height, e.g. decitabine - L01BC08 - DDD=36mg; 2) treatment courses, (criterium: assumed mean administered dose divided by treatment course duration in days, e.g. Ipilimumab - L01FX04 - DDD=10mg; 3) topical applications of an amount of pharmaceutical product (mean amount of pharmaceutical product administered daily, e.g. fluorouracil and salicylic acid - L01BC52 - DDD=5ml).

Conclusions: A small set of additional criteria was sufficient to assign a DDD to all the ATC L codes of interest. Application of the assigned DDD at international level should take into account possible differences in marketed formulations, main indication of use and possible substantial differences in average population height and weight.