Drug Safety

, Volume 26, Issue 3, pp 145–158 | Cite as

Methods and Pitfalls in Searching Drug Safety Databases Utilising the Medical Dictionary for Regulatory Activities (MedDRA)1

  • Elliot G. BrownEmail author
Leading Article


The Medical Dictionary for Regulatory Activities (MedDRA) is a unified standard terminology for recording and reporting adverse drug event data. Its introduction is widely seen as a significant improvement on the previous situation, where a multitude of terminologies of widely varying scope and quality were in use. However, there are some complexities that may cause difficulties, and these will form the focus for this paper.

Two methods of searching MedDRA-coded databases are described: searching based on term selection from all of MedDRA and searching based on terms in the safety database. There are several potential traps for the unwary in safety searches. There may be multiple locations of relevant terms within a system organ class (SOC) and lack of recognition of appropriate group terms; the user may think that group terms are more inclusive than is the case. MedDRA may distribute terms relevant to one medical condition across several primary SOCs. If the database supports the MedDRA model, it is possible to perform multiaxial searching: while this may help find terms that might have been missed, it is still necessary to consider the entire contents of the SOCs to find all relevant terms and there are many instances of incomplete secondary linkages. It is important to adjust for multiaxiality if data are presented using primary and secondary locations. Other sources for errors in searching are non-intuitive placement and the selection of terms as preferred terms (PTs) that may not be widely recognised. Some MedDRA rules could also result in errors in data retrieval if the individual is unaware of these: in particular, the lack of multiaxial linkages for the Investigations SOC, Social circumstances SOC and Surgical and medical procedures SOC and the requirement that a PT may only be present under one High Level Term (HLT) and one High Level Group Term (HLGT) within any single SOC. Special Search Categories (collections of PTs assembled from various SOCs by searching all of MedDRA) are limited by the small number available and by lack of clarity about criteria applied in their construction.

Difficulties in database searching may be addressed by suitable user training and experience, and by central reporting of detected deficiencies in MedDRA. Other remedies may include regulatory guidance on implementation and use of MedDRA. Further systematic review of MedDRA is needed and generation of standardised searches that may be used ‘off the shelf’ will help, particularly where the same search is performed repeatedly on multiple data sets. Until these enhancements are widely available, MedDRA users should take great care when searching a safety database to ensure that cases are not inadvertently missed.


Data Retrieval Primary Location Relevant Term Rift Valley Fever System Organ Class 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



No funding was obtained from any source for the preparation of this paper. The author participated in the process of creating MedDRA, is a member of the CIOMS working group on standard MedDRA searches, consultant and trainer to companies and regulatory authorities on MedDRA, and has commercial interests in software associated with its use.


  1. 1.
    Eudralex Collection. The rules governing medicinal products in the European Union. Vol. 9, Pharmacovigilance. Eudralex collection [online]. Available from URL: [Accessed 2002 Aug 31]Google Scholar
  2. 2.
    The ICH process for harmonization of guidelines [online]. Available from URL: [Accessed 2002 Aug 31]Google Scholar
  3. 3.
    MedDRA®. Term selection points to consider, release 3.0. Application to adverse drug reactions/adverse events and medical and social history [online]. Available from URL: http://www.MedDRA® [Accessed 2002 Aug 31]Google Scholar
  4. 4.
    Brown EG, Douglas S. Tabulation and analysis of pharmacovigilance data using the Medical Dictionary for Regulatory Activities. Pharmacoepidemiol Drug Saf 2000; 9: 479–89CrossRefGoogle Scholar
  5. 5.
    Fescharek R, Dechert G, Reichert D, et al. Overall analysis of spontaneously reported adverse events: a worthwhile exercise or flogging a dead horse? Pharmaceutical Med 1996; 10: 71–86Google Scholar
  6. 6.
    Goldman SA. Adverse event reporting and standardizing medical terminologies: strengths and limitations. Drug Inf J 2002; 36: 439–44Google Scholar
  7. 7.
    Brown EG. Effects of coding dictionary on signal generation: a consideration of use of MedDRA compared with WHO-ART. Drug Saf 2002; 25(6): 445–52PubMedCrossRefGoogle Scholar
  8. 8.
    New CIOMS Working Group: rational use of MedDRA terminology for drug safety database searches. Current programme and planned activities [online]. Available from URL: [Accessed 2002 Aug 31]Google Scholar

Copyright information

© Adis International Limited 2003

Authors and Affiliations

  1. 1.Elliot Brown Consulting LtdBarnetUnited Kingdom

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