Inventory of Health Care Information Standards. International Conference on Harmonization


Representation includes: US Food and Drug Administration

European Union

Japan's Ministry of Health and Welfare

PhRMA (Pharmaceutical Research and Manufacturers of America)

JPMA (Japanese Pharmaceutical Manufacturers Association)

EFPIA (European Federation of Pharmaceutical Industries


ANSI Accreditation

Not ANSI Accredited

International Medical Terminology (IMT)

Contact For More Information

Kathryn A. Huntley

Standardized Nomenclature Program Manager

Food and Drug Administration

HF-21 Rm 16B-45

5600 Fishers Lane

Rockville, MD 20857

(301) 594-6491 (voice)

(301) 594-0829 (fax)

Description of Standard

The International Medical Terminology (IMT) is a medical terminology designed to support the classification, retrieval, presentation, and communication of medical information throughout the medical product regulatory cycle. The foundation of the IMT is the Medical Dictionary for Drug Regulatory Affairs (MEDDRA) developed by the UK Medicines Control Agency (MCA) in its Adverse Drug Reactions On-line Information Tracking System (ADROIT).

The IMT is superior to other medical terminologies in its scope, size, and specificity. Included in the IMT are terms describing diseases, diagnoses, signs, symptoms, therapeutic indication names, and qualitative results of investigations (e.g. laboratory tests, radiological studies), medical and surgical procedures, and terms describing medical, social, and family history. The IMT consists of a five level hierarchy, starting with 26 System Organ Classes (SOCs), that represent the highest level groupings of the terminology. Including all levels it contains approximately 40,000 terms. The Preferred term (PT) is the internationally agreed upon level at which regulatory information is to be exchanged. The IMT contains approximately 8,800 PTs, vastly improving the specificity of exchanged regulatory information over previous thesauri.

The current version of the IMT is available in multiple formats:

  • ASCII text files
  • Access Database
  • On the FDA's Standardized Nomenclatures Database (SND).
  • The thesaurus is also available in paper format.

Readiness of Standard

A.This is not a guideline

B.The implementable version will be a combination of products, the terminology and a maintenance organization. The terminology will be completed March 1997 the maintenance organization will be operational December 1997.

C.The 1.5 version of the terminology is obtainable through the FDA at no cost. The final version will be available through the maintenance organization.

D.There will be a user manual, help desk support etc. through the maintenance organization.

E.There will be a single version, multiple translations i.e. Japanese, Spanish, French and German to begin.




I.The 1.5 version of the terminology is available for review. The FDA has rewritten 8 of the 26 System Organ Classes. The structure of terminology will not change just the terms populating the various levels below the System Organ Class level.

J.The final review of the US proposals, and the review and repopulation of the mid-levels to aid in data aggregation and display as well as the assignment of codes.

AA. ICH Expert Working Group meeting the first week of January 1997, the presentation to the ICH Steering Committee the first week of March 1997.

BB. ICH Steering Committee meeting March 1997, Selection of the Maintenance Organization July 1997, Terminology available December 1997

CC. none

Indicator of Market Acceptance

A. 308 copies of Version 1.0 and 386 copies of Version 1.5 have been distributed in North America to date. There are also distribution points in Japan and Europe.

B. none currently

C.A closely related product is currently being used in the ADROIT system of the UK's Medicines Control Agency.

D.The development of this standard under the ICH umbrella is very important in that once agreed upon by the regulators they are committed to implementing it. That means the regulatory authorities of Europe, United states and Japan will implement therefore the industries in those regions will also implement it. It is being reviewed by the World Health Organization for use by WHO countries and also by the WHO Drug Monitoring Program in Upsala Sweden.

Within the US, the National Cancer Institute's Cancer Therapy Evaluation Program is planning to adopt this terminology for use in collecting cancer clinical trial data.

Level of Specificity

(A) The IMT is not a guideline.

(B) The IMT's hierarchy consists of five levels and was designed to facilitate both coding and retrieval of medical information. These levels include System Organ Class (SOC), the broadest term; High Level Group Term (HLGT); High Level Term (HLT); Preferred Term (PT); and Lowest Level Term (LLT). Concepts in the vocabulary are grouped based upon inclusive relationships. The hierarchy can be used to locate concepts at a desired degree of specificity.

The following is a description of the IMT hierarchical levels from the most specific, or granular, to the broadest.

LLT - The Lowest Level Terms provide the most specific terms in the vocabulary. The LLTs are not used for reporting, but help define the scope of the preferred term to which they are linked, and provide a collection of terms used in verbatim reports to describe adverse experiences or medical history. In the IMT, the LLTs contain both synonyms and quasi-synonyms. In a strictly controlled thesaurus, the finest division of vocabulary consists only of synonyms and lexical variants (spelling and word order variations). In practical medical coding vocabularies, however, this rule is not rigorously enforceable. Terms that have similar meanings, or which describe similar concepts, are often grouped under the same preferred term.

PT - The preferred term is the internationally agreed upon level at which regulatory information is to be exchanged. The PT represents a single, unambiguous, clinical concept. Terms at this level should be at a level of specificity to code regulated indications and to capture signals of specific significant adverse events. The LLTs under each PT indicate the intended scope of the term. A PT may be linked to one or more SOCs, but is assigned to only one Primary SOC under which it is grouped for cumulative data outputs to prevent duplicate counting.

HLT - A High Level Term groups together PTs which are related by anatomy, pathology, physiology, etiology or function for data retrieval and presentation purposes only. An HLT may be linked to one or more HLGT(s) or SOC(s).

HLGT - High Level Group Terms, like the HLTs, are broad concepts used for grouping clinically related terms for data retrieval and presentation. They may be linked to one or more SOC(s).

SOC - The System Organ Class represents the broadest collection of concepts for retrieval in the vocabulary. SOCs group concepts according to anatomical or physiological system, e.g. Gastrointestinal disorders; body organ, e.g. Disorders of the eye; mechanism, e.g. Infections and infestations; and purposes, e.g. Surgical and medical procedures.

It does not reference other standards.

FDA recommendation for the IMT coding scheme (this is only a recommendation and has not been finalized):

  • IMT use a sequential numbering (non-expressive, numeric code) method with a length of at least 8 for the terminology coding scheme.
  • Unique codes be applied to all terms across all categories.
  • After term changes to MEDDRA Version 1.5 are complete, a numeric code be applied to terms sequentially by alphabetical order as the last step in the development process for the IMT.
  • Use 10000001 as the first code applied to the first term sorted alphabetically in order to enforce a length of 8.

User Guide to be developed.

Schedule for IMT Implementation:

  • ICH approval - 3/97
  • Wide Availability - 12/97

Relationships With Other Standards

Terms from other commonly used medical thesauri have also been added to the IMT to make the transition from these other vocabularies to the IMT easier. These include the Food and Drug Administration Coding Symbols for a Thesaurus of Adverse Reaction Terms (COSTART), the World Health Organizations Adverse Reaction Terminology (WHO-ART), the International Classification of Diseases, version 9, Clinical Modifications (ICD-9-CM), the Japanese Adverse Reaction Thesaurus (JART), and the Hoechst Adverse Reaction Terminology (HARTS).

There are some medical concepts that are not included in the IMT. The following areas are considered outside the scope of this regulatory terminology:

  • Drug product terminology (i.e., complete listing of drug names);
  • Equipment, device or diagnostic product terminology (i.e., complete listing of medical devices, diagnostic equipment or in vitro diagnostic products);
  • Device failure terminology;
  • Clinical trial study design terminology;
  • Patient demographic terminology;
  • Qualifiers that refer to populations rather than individual patient results (e.g., rare, frequent);
  • Numerical values associated with investigations or observations (e.g., numeric laboratory test results)
  • Descriptors of severity (e.g., severity, mild).

Identifiable Costs

Cost of licensure is yet undetermined but the goal is to make the internationally maintained terminology as inexpensive and readily available as possible. In all regions consideration must be given to the developing nations under WHO as well as the start up and specialty industries throughout the world.