MedDRA or Medical Dictionary for Regulatory Activities is a clinically validated international medical terminology dictionary (and thesaurus) used by regulatory authorities in the pharmaceutical industry during the regulatory process, from pre-marketing (clinical research phase 0 to phase 3) to post-marketing activities (pharmacovigilance or clinical research phase 4), and for safety information data entry, retrieval, evaluation, and presentation. In addition, it is the adverse event classification dictionary endorsed by the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH).

Originally available in English and Japanese, MedDRA is now also translated into Chinese, Czech, Dutch, French, German, Hungarian, Italian, Portuguese, Russian, and Spanish.[1] MedDRA is widely used internationally, including in the United States, European Union, and Japan. Its use is currently mandated in Europe and Japan for safety reporting.

Organization of the dictionary

The MedDRA dictionary is organized by System Organ Class (SOC), divided into High-Level Group Terms (HLGT), High-Level Terms (HLT), Preferred Terms (PT) and finally into Lowest Level Terms (LLT).[2] In addition, the MedDRA dictionary includes Standardized MedDRA Queries (SMQs). SMQs are groupings of terms that relate to a defined medical condition or area of interest.

Individual cases are usually coded for data entry at the most specific (LLT) level, and outputs of counts or cases are usually provided at the PT level. The higher levels (HLT, HLGT and SOC) as well as SMQ are used for searching and for organisation and subtotalling of outputs.

MedDRA hierarchy

The hierarchy provides degrees or levels of superordination and subordination. The superordinate term is a broad grouping term applicable to each subordinate descriptor linked to it. Hierarchical levels thus represent vertical links in the terminology.[3]

Hierarchies are an important mechanism for flexible data retrieval and for the clear presentation of data. The five-level structure of this terminology provides options for retrieving data by specific or broad groupings, according to the level of specificity required. The Lowest Level Term (LLT) level provides maximum specificity.[3]

The terminology was not developed as a formal classification or taxonomy; each level in the hierarchy may reflect a variable degree of specificity or “granularity” from one System Organ Class to another. High Level Terms (HLTs) and High Level Group Terms (HLGTs) facilitate data retrieval and presentation by providing clinically relevant grouping of terms. Collectively, the HLT and HLGT levels are sometimes referred to as the “grouping terms” in MedDRA.[3]

The 27 System Organ Classes (SOCs) represent parallel axes that are not mutually exclusive. This characteristic, called “multi-axiality,” allows a term to be represented in more than one SOC and to be grouped by different classifications (e.g., by etiology or manifestation site), allowing retrieval and presentation via different data sets. Grouping terms are pre-defined in the terminology and not selected on an ad hoc basis by data entry staff. Rather, the terminology is structured so that selection of a data entry term leads to automatic assignment of grouping terms higher in the hierarchy. Multi-axial links of terms are pre-assigned in MedDRA, ensuring comprehensive and consistent data retrieval, irrespective of which SOC is selected at data retrieval.[3]

According to MedDRA 22.0 (March 2019):

  • SOC – 27
  • HLGT – 337
  • HLT – 1737
  • PT – 23708
  • LLT – 80262

Maintenance of MedDRA

MedDRA is managed by the MSSO (Maintenance and Support Services Organization). The International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) is the Trustee of the International Conference on Harmonisation (ICH) Steering Committee and holds the intellectual property rights (ownership) of MedDRA. The ICH has contracted Northrop Grumman to act as the MSSO. MedDRA is free for regulators and priced according to company revenue for industry. The Japanese counterpart for MSSO is called JMO.[4]

The MSSO updates MedDRA according to subscriber change requests, for example to add a new medical concept that is yet to be in MedDRA or to change an existing concept. The decisions are made by international medical officers on how to map the terminology within the grouping categories according to a general consensus based on language considerations internationally.

The MSSO releases updated MedDRA versions twice a year - in March and September. The English translation is released on the 1st of March and September and all other translations are released on the 15th. The March release is the main annual release and contains changes at the HLT level and above along with LLT and PT changes. The September release typically contains changes only at the LLT and PT level. The March 2019 Version 22.0 release is the current version.

See also


  1. "Welcome to MedDRA".
  2. "What are the structural elements of the terminology in MedDRA?". MedDRA FAQ. Retrieved 25 January 2012.
  3. "Introductory Guide MedDRA Version 21.0" (PDF). ICH. March 2018. Retrieved 9 January 2019. Content is copied from this source, which is © ICH. It may be used, reproduced, incorporated into other works, adapted, modified, translated or distributed under a public license provided that ICH's copyright is acknowledged.
  4. "About MSSO".
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.