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Drug-related problems are one of the cornerstones of pharmaceutical care. Therefore the PCNE working group on Drug-related problems develops, maintains, supervises and evaluates a DRP-classification.

In September 2009, the working group on Drug-Related Problems of the Pharmaceutical Care Network Europe has been officially established, although it existed already informally since 2001. The working group is currently managed by Dr. Tommy Westerlund (Sweden), Dr. Nejc Horvat (Slovenia) and Ina Richling, PharmD (Germany).

The working group can be contacted by email at drp@pcne.org.

Download Classification V 9.1 en (2026)

Version 9.1 is ready and available, it now includes a simplified causes domain for seamless care. Please also note that the contact email address has been adapted, due to organisational changes in the working group and PCNE.
Please note that Version V8 is not compatible with earlier versions, due to some fundamental changes. But V8 is more or less compatible with the Version 9, with the help of a conversion table (C8 is new, C9 is the old C8). The version 9.1 is the result of an international validation round of V9.0. It has been validated by an international group of experts and is available in English, Traditional Chinese, German, Turkish and Croatian. V9.0 is also available in Mandarin Chinese, Montenegrin, Turkish and Indonesian. Version 8.03 is available in Traditional Chinese and Turkish (see below).

“A Drug-Related Problem is an event or circumstance involving drug therapy that actually or potentially interferes with desired health outcomes.”

Disclaimer:

This classification may be used exclusively for Pharmaceutical Care Research and Practice, provided that the PCNE Association is informed of its use and of the results of any validations. Any use by commercial entities, or any use with a commercial purpose, is prohibited unless the user has obtained explicit permission from the PCNE Board. These conditions reflect PCNE’s long-standing policy and apply to both the current version and earlier versions of the classification. The exclusive place of jurisdiction for any dispute arising from the use of this classification is the District Court of The Hague, the Netherlands.”

International Validation Project 2019-2021

With the increasing international use of the PCNE-DRP Classification, and many translations, a more thorough validation is necessary; just face validity is not enough. There are eight criteria that should be considered in the selection of drug related problem classifications, those criteria in the mean time also constitute criteria for validation.

Appropriateness: is the classification content appropriate to the questions which the classification seeks to address, namely coding drug-related problems, its causes and interventions?

Acceptability: is the DRP-classification instrument acceptable to health care professionals and researchers, for the aims that it has been developped for?

Feasibility: is the instrument easy to administer and are the results easy to process?

Interpretability: how interpretable are the scores of the instrument?

Precision: how precise are the scores of the instrument?

Reliability: does the instrument produce results that are reproducible and internally consistent?

Validity: does the instrument document what it claims to measure?

Responsiveness: does the instrument offer options to follow interventions and outcomes of interventions? This aspect is obviously closely linked to precision.

Validation V9.0

With the construction of the classification V9.0, a new international validation project was also started, based on a validation set of cases (Set 2019). In this validation round, the interpretability, precision and reliability aspects of validity are being assessed, as well as the acceptability.

At the preliminary evaluation of this validation round with the results of approx. 50 respondents, a number of issues became obvious. These issues were discussed with pharmaceutical care experts during the Working Symposium 2020 in Egmond aan Zee, and were found to be cause by the classification itself as well as the cases used. During the months March and April 2020, the working group adapted the classification based on the results of the discussions in Egmond, leading to a version 9.1. Also the cases were adapted, leading to a version Set 2020.

The report of the first validation round can be found here and is publicly available. The data are also available, but only for PCNE members (password protected) and the national coordinating centres.

Validation V 9.1

The adapted classification and cases went into international validation round 2. 158 pharmacists from 12 countries completed the survey. The report of the second validation round can be found here and is publicly available. The executive summary is also available. These issues were discussed with pharmaceutical care experts during the online Working Conference 2021.

On the 6th February 2019 the DRP-group had another meeting to discuss V8.02 of the DRP classification. This version now has been translated in a number of languages, and more translations are under way. Nevertheless a small number of issues has come up, and small adaptations proved to be desirable. See the meeting report.

At the same time, V9.0 was under development and has been finalised. That version is being validated, and the preliminary validation results were discussed in Egmond, 7-8 February 2020. Working group participants decided that a number of cases should be adapted and replaced, but also suggested some minor and major changes to the classification. The working group has implemented the changes in the cases, and minor changes in the classification, and a new validation round will be started soon. Major changes to the classification must wait till a totally new version will be developed.

For more information, mail to drp@pcne.org.

During the first Working Conference of the Pharmaceutical Care Network Europe in January 1999 in Hilleroed, Denmark, a classification scheme was constructed for drug related problems (DRPs). In the years thereafter the classification underwent many tests and changes, leading to a number of new versions.

The definition of drug-related problems, and the 2009 version of the PCNE-DRP classification have been extensively discussed during a dedicated and important PCNE Working Symposium on Drug Related Problems in Geneva. There were international 18 experts present who discussed definitions, the new version (V6) of the PCNE DRP classification and validation issues.

The different abstracts, presentations and reports from that meeting are available from Working Symposium 2009.

In 2017, a new discussion round was held between experts, and this was the start for the creation of a new version. One of the essential new elements was a domain for the way that the proposed interventions are presented, and one for the level acceptance of the intervention. The domain outcome was also scrutinised and adapted.

After a quick validation and a new discussion on the validation process in Heidelberg, some minor changes were implemented and V8 became the new standard. During the 2019 Working Conference in Egmond, the Classification and its validation were again discussed, and this lead to some minor changes. After a new validation round, the current version (V9.1) was prepared, and includes a simplified domain on possible causes that can be found in seamless care (patient transfer between different settings or clinical departments). V 9.1 comes into effect per 20-5-2020.

Additional information can be obtained from the DRP Working group of the PCNE at drp@pcne.org.

Latest version and translations 

Please note that per 1-5-2020, the latest version in English and traditional Chinese are V9.1. Previous versions are no longer supported, but some can still be downloaded.

The versions 8 and 9 are not compatible with earlier versions, due to some fundamental changes. But V9 is compatible with the versions 8, with small adaptations. The English edition of this version will be validated. There is a Mandarin, German, and Montenegrin translation of Version 9.0, and a Traditional Chinese and Turkish translation of Version 8.03. Versions in Russian, Indonesian and Ukrainian are under scruteny.

There is a Spanish and Croatian version version of the Classification V6.2. These versions are no longer supported by PCNE but have proven their worth in several projects.

Please note that there is a copyright on the material, and you should inform the PCNE DRP working group if you want to use or publish the Classification or related materials (any version). Any other question can also be sent to the working group at drp@pcne.org.

The classification has changed significantly since its first version. A list of the changes can be found here.