Regulation (EU) 2017/745 on medical devices (MDR) and Regulation (EU) 2017/746 on in vitro diagnostic medical devices (IVDR) aim to ensure the general safety, efficacy, and performance of medical devices and IVDs. A critical aspect of these regulations is the assessment of technical documentation (TD), which is required for the certification of devices before they can enter the market. However, for Class IIa / IIb medical devices and Class B and C IVDs, it is mandatory to undergo a comprehensive technical assessment conducted by a NB, and the technical documentation will be subjected to sampling. In particular, the MDCG 2019-13 document guides the sampling of MDR Class IIa, IIb and IVDR Class B, and C devices for the assessment of technical documentation.

The term “Sampling Devices” denotes a systematic procedure for choosing representative samples of medical devices for assessment. This sampling process is vital in the EU MDR/IVDR technical documentation of medical devices and IVDs.

This article aims to provide a comprehensive understanding of the need for sampling, the criteria for sampling, how technical documentation is assessed by Notified Bodies, exemptions to the process, and how manufacturers benefit from this approach.

The need for sampling is the complexity and variety of medical devices and in vitro diagnostic devices available on the market. Under the MDR and IVDR, devices are classified into risk categories ranging from Class I (low risk) to Class III (high risk) for medical devices and Class A to Class D for IVDs. For devices that fall under Class IIa, IIb (MDR) and Class B, C (IVDR), It is not feasible or necessary to individually assess the technical documentation of each device.

The sampling of devices ensures that Notified Bodies can assess a representative sample of devices to confirm compliance with regulatory requirements before issuing certifications. This approach is particularly beneficial for manufacturers with a wide range of products, as it balances thorough regulatory scrutiny and operational efficiency. By sampling certain devices, the Notified Body can assess the entire device range or product family without having to review each one in detail.

Article 52(4) and (6) of MDR and Article 48(7) and (9) of IVDR require the assessment of at least one representative device per generic device group (Class IIb and Class C) and each category of devices (Class IIa and Class B) before certification.

The category of devices refers to the relevant MDA/MDN codes for medical devices (MDR) or IVR codes for in vitro diagnostic devices (IVDR) as specified in Regulation (EU) 2017/2185. These codes are used to designate notified bodies responsible for conformity assessments.

The generic device group is defined differently for MDR and IVDR:

• For MDR, it corresponds to the 4th level of the European Nomenclature on Medical Devices (EMDN), which is a combination of one letter and six digits.
• For IVDR, it corresponds to the 3rd level of the EMDN, which is a combination of one letter and four digits, along with the most appropriate IVP code.

Annex IX (Sections 2.3 and 3.4) and Annex XI (Section 10) of MDR: QMS assessment must include technical documentation assessment for representative devices.

Annex VII (Section 4.5.2(a)): Notified bodies must create and update a sampling plan for technical documentation assessment before audits.

Sampling Plan: The Notified Body (NB) plays a crucial role in preparing the sampling plan for the assessment of the EU Medical Device Regulation (MDR) and In Vitro Diagnostic Regulation (IVDR) technical documentation. This plan includes essential details such as:

• Devices covered by the certificate
• Basic UDI-DI
• Generic device group (for Class IIb)
• Generic device group plus IVP code (Generic device groups for Class C devices will consist on an EMDN + an IVP code. Therefore, when different products are covered under the same EMDN but correspond to different IVP codes, the notified body will assign the most appropriate IVDP code to each device.) (for Class C devices)
• Category of devices (for Class IIa / Class B devices)
• Identifier of the respective technical documentation
• Planned assessment dates
• Status of assessments

The sampling plan should be updated as needed based on criteria defined in the guidance and post-certification activities. This includes considering outcomes from scientific and clinical data screening, post-market information, and vigilance data reviews.

If the manufacturer changes the product range during the certificate’s validity, the notified body must review and update the sampling plan accordingly. For new devices not covered by existing generic groups/categories, initial sampling criteria apply. During re-certification, the sampling plan should be updated with samples to be assessed in the upcoming certification period and kept up to date.

Notified bodies must assess technical documentation in preparation for audits, completing this assessment in time for the audits.

The MDCG 2019-13 guidance outlines specific criteria for sampling MDR and IVDR devices. The criteria are designed to ensure that the sampled devices are representative of the entire group. The sampling process is covered by both quantitative and qualitative criteria.

Quantitatively, the MDR and IVDR regulations specify minimum sampling requirements.

Sampling before issuing a QMS certificate: Regulations require the notified body to assess the technical documentation of at least one representative device from each generic device group must be assessed before a quality management system (QMS) certificate can be issued.

Class IIb and Class C Devices

• Assess at least one representative device per generic device group.
• Determine the number of generic device groups covered in the application.
• Select at least one representative device per group covered by a Basic UDI-DI and assess its technical documentation.

Class IIa and Class B Devices:

• Assess at least one representative device per category of devices.
• Determine the number of categories of devices covered in the application.
• Select at least one representative device per category covered by a Basic UDI-DI and assess its technical documentation.

Sampling during surveillance: After issuing the certificate, the notified body will continue to assess technical documentation in line with the sampling plan. Surveillance assessment of the technical documentation, which means that at least one technical documentation must be reviewed each year.

Generic Device Groups for Class C Devices:

• Consists of an EMDN + an IVP code.
• Different products under the same EMDN but different IVP codes will have the most appropriate IVDP code assigned to each device.

Annual Review:

• At least one technical documentation must be reviewed each year.

Coverage of the Entire Device Range:

• Notified bodies must ensure that the entire device range is covered during the certificate’s validity.
• At least one device per category (Class IIa and Class B) and one device per generic device group (Class IIb and Class C) should be sampled and assessed between the issue and expiry of the certificate.

Representative Sampling:

• The number of samples to be assessed must be selected on a representative basis.
• 15% of devices from each category and each generic device group covered in the certificate will be sampled during its validity, considering a maximum validity of 5 years.

Focus During Surveillance Audits:

• If the certificate contains very few devices and their technical documentation has already been reviewed, the focus will be on the review of technical documentation related to post-market surveillance.

Even Distribution of Sampling:

• Devices to be sampled after the certificate issuance should be spread evenly during the certificate’s validity.
• The notified body may perform different numbers of reviews each year for various reasons (e.g., workload, vigilance concern) as long as all initially determined assessments are performed during the surveillance period.
• This approach ensures compliance with the minimum requirements and maintains the integrity of the surveillance process.

The qualitative aspects of devices also play a crucial role in sampling. Notified Bodies consider several factors when drawing up sampling plans for medical devices. Here are the main points:

1. Similarities in Design and Technology: Devices that share similar design, technology, manufacturing, and sterilization methods may already be grouped. However, each device must still be individually considered.
2. Novelty of Technology: Newer technologies are often prioritized over well-known ones unless there are specific concerns about the latter. regard to physical, chemical, biological, or clinical properties must be individually considered when prioritizing the review of one device over another.
3. Intended Purpose: The intended use of the device is a crucial factor in determining its priority for review.
4. Previous Assessments: Results from previous assessments, including physical, chemical, biological, or clinical properties, must be considered.
5. Inherent Risk: The inherent risk associated with different devices within the same category or generic device group is a significant factor. Higher-risk devices are typically prioritized.
6. Documentation: The notified body must document the rationale for the samples taken, specifying the criteria considered.
7. Sampling Frequency: Each device should only be sampled once during the certificate’s validity period unless new information or vigilance cases arise that necessitate additional sampling.

These criteria ensure a thorough and risk-based approach to the sampling and review of medical devices, aiming to prioritize safety and efficacy.