IMDRF codes provide a standardized method for describing and classifying incidents related to medical devices. These codes are essential for standardizing communication between regulatory authorities and Manufacturers, as well as for harmonizing regulatory practices on a global scale.
About the IMDRF
The International Medical Device Regulators Forum (IMDRF) was founded in October 2011 and is the successor to the Global Harmonization Task Force (GHTF), which was dissolved in 2012. The IMDRF is composed of international regulatory authorities in the field of medical devices and works to advance the international convergence and harmonization of medical device regulations. Its current members are Australia, Brazil, Canada, China, Japan, Russia, Singapore, South Korea, Switzerland, the United Kingdom, the United States, and the European Union. The IMDRF’s current working groups include:
- Adverse Event Terminology
- Artificial Intelligence/Machine Learning-Enabled
- Clinical Evidence for In Vitro Diagnostic Medical Devices
- Foundational Documents
- Good Regulatory Review Practices
- Medical Devices Cybersecurity Working Group
- Quality Management Systems
- Software as a Medical Device
The working groups draw on the expertise of various stakeholder groups, such as industry, academia, healthcare professionals, and consumer and patient groups. The Adverse Event Terminology Working Group developed a uniform terminology and a standardized approach for describing information on incidents involving medical devices: the IMDRF codes.
IMDRF codes implementation
The IMDRF codes, also known as “Terminologies for Categorized Adverse Event Reporting (AER),” are divided into four categories and comprise seven subgroups, designated as Annexes A through G. The categories and subgroups are broken down as follows:
IMDRF Category | Associated Subgroups |
Medical Device Problem | Medical Device Problem (Annex A) |
Cause Investigation | Type of Investigation (Annex B) Investigation Findings (Annex C) Investigation Conclusion (Annex D) |
Health Effects | Clinical signs, symptoms, and conditions (Annex E) Health impact (Annex F) |
Medical Device Parts and Components | Components and parts (Annex G) |
Annex A contains terms and codes for describing issues related to a medical device, such as malfunctions, operational failures, or failures that have occurred in medical devices.
Annexes B, C, and D pertain to the investigation of the cause of an incident. Annex B contains terms and codes for describing the type of investigation conducted in connection with an incident (on the device). The terms and codes in Annex C are used to describe the results of the investigation, and the terms and codes in Annex D are used to describe the conclusions drawn from the investigations.
The terms and codes in Annexes E and F are used to describe the impact on affected individuals. Annex E contains terms and codes for describing the clinical signs, symptoms, and medical conditions that occur in the affected individual as a result of an incident. Annex F contains terms and codes for describing the health consequences of a medical device’s Adverse event for the affected individual.
Finally, Annex G contains terms and codes for describing the parts/components that were involved in or affected by an Incident.
To characterize a case, at least one code from the relevant categories is assigned in each subgroup. The codes always consist of a letter followed by a sequence of numbers. The letter corresponds to the letter of the associated subgroup/annex. The numbers refer to the internal hierarchy within the annex. The internal hierarchy within the annex can be up to three levels deep. As the level depth increases, the details become more specific. This can result in the following hierarchy, as illustrated here using Annex A as an example:
Level 1: A07 Electrical/Electronic Property Problem
Level 2: A0705 Battery Problem
Level 3: A070501 Battery Problem: High Impedance, A070502 Battery Problem: Low Impedance, A070503 Failure to Run on Battery, A070504 Premature Discharge of Battery
It is recommended to code an incident in as much detail as possible. However, depending on the available data, it may only be possible to assign a Level 2 or Level 1 code with sufficient certainty. In practice, multiple codes from different categories are often used in combination to adequately describe an incident.
The current annexes, containing a detailed list of codes, definitions, and explanatory notes, can be found on the IMDRF website (imdrf.org).
Since February 2026, a separate IMDRF practice guideline on code selection has also been available (IMDRF/AET WG/N86 FINAL:2026, “Considerations for the Selection of IMDRF Adverse Event Terminology – A Guide for Industry Partners and Healthcare Providers”). It is intended for Manufacturers and other reporters and provides specific guidance on consistent code selection. Since the 2025/2026 updates, Annexes A through G are no longer published as separate documents but as a consolidated workbook with one spreadsheet per annex.
Importance of IMDRF codes for medical device manufacturers
IMDRF codes play a key role in the manufacturer’s post-market surveillance and vigilance system. The Manufacturer Incident Report (MIR) form for reporting serious incidents in the European Union mandates the use of the IMDRF Adverse Event Terminology.
As of November 1, 2025, the version of the MIR form agreed upon between European Authorities and manufacturers’ associations is mandatory. Version 7.2.1, which was previously used, is no longer provided by the BfArM. Consequently, the form was updated to version 7.3.1, the use of which has been mandatory since May 1, 2026. Serious incidents are currently still reported via the MIR form. Mandatory use of the EUDAMED vigilance module has not yet been introduced.
In addition, IMDRF codes can facilitate internal searches and the systematic analysis of incidents. In particular, they support the identification of comparable events, which must also be specified in the serious incident report, as well as the conduct of trend analyses in accordance with Article 88 of the MDR. Furthermore, the guidance on the Periodic Safety Update Report (PSUR) (MDCG 2022-21) refers to the use of IMDRF codes in the preparation of the PSUR.
For manufacturers operating internationally in particular, the IMDRF Adverse Event Terminology represents an important tool for standardized communication regarding medical device incidents.
