Skip to main content

Clinical evaluation requirements

Regulatory basis

Clinical evaluation is required to demonstrate conformity with the Essential Requirements of Schedule 1, UK MDR 2002 — specifically ERs 1 (safety), 2 (risk minimisation), 3 (performance), and 6 (acceptable side effects). MHRA regards MEDDEV 2.7/1 Rev.4 as the primary guidance for clinical evaluation methodology, even though it is an EU document.

Disclaimer

This site provides general information only. Clinical evaluation is complex and often requires specialist expertise. Consult MHRA guidance and a qualified clinical affairs professional.

What is clinical evaluation?​

Clinical evaluation is the systematic and planned process to continuously generate, collect, analyse, and assess the clinical data pertaining to a device, in order to verify the clinical safety and performance of the device when used as intended by the manufacturer.

Clinical evaluation is not a one-time pre-market activity — it is an ongoing lifecycle obligation.

The output of the clinical evaluation process is the Clinical Evaluation Report (CER).

Clinical data sources​

Clinical evidence can come from multiple sources, which are used in combination:

1. Literature data on the device itself​

Published clinical data from studies, case reports, registry entries, or surveillance reports specifically concerning the device under evaluation. This is the highest-quality source.

2. Equivalent device data​

Where sufficient clinical data on the device itself does not exist, data from a clinically equivalent device may be used — provided equivalence can be demonstrated across three dimensions:

Equivalence dimensionRequirements
ClinicalSame intended purpose, same medical condition/site, same patient population, similar severity/stage of disease
TechnicalSame design principles, materials, energy output/type, operating principles, deployment method
BiologicalSame tissues contacted, same type and duration of contact, same exposure to body fluids

All three dimensions must be met simultaneously. Partial equivalence is not sufficient. Equivalence must be documented with objective evidence — not assertions.

EU MDR raised the bar on equivalence

EU MDR 2017/745 (applying in NI) requires substantially stricter demonstration of equivalence than the former MDD (the source of UK MDR 2002 requirements). For Class III and implantable devices, EU MDR requires a contract with the equivalent device manufacturer providing access to their technical documentation. UK MDR 2002 does not have this specific requirement — but MHRA expects rigorous equivalence justification nonetheless.

3. Clinical investigation data​

Data from a clinical investigation specifically conducted on the device — a prospective, controlled study with defined endpoints, ethics approval, and protocol. Clinical investigations are the highest-quality clinical evidence source. They are not always required but are expected for novel or high-risk devices where equivalent device data is insufficient.

4. Post-market clinical data​

For devices already on the market:

  • Adverse event reports and complaint data
  • Post-market clinical follow-up (PMCF) study results
  • Registry data
  • Published post-market studies

The clinical evaluation process (MEDDEV 2.7/1 approach)​

MHRA endorses MEDDEV 2.7/1 Rev.4 as the methodology for clinical evaluation:

Stage 0: Scope definition​

Define precisely what the CER will cover: the device, its intended purpose, the target patient population, the clinical claims to be substantiated.

Conduct a systematic literature search of relevant databases (PubMed, Embase, Cochrane, etc.) using a pre-defined search strategy. The search must be:

  • Reproducible (documented search strategy, date, databases)
  • Sufficiently broad (device, equivalent devices, clinical condition, complications)
  • Current (updated at each CER update)

Document all searches in a literature search protocol and report.

Stage 2: Appraisal of literature​

Each relevant retrieved article must be appraised for methodological quality:

  • Study design (RCT > cohort > case series > case report)
  • Risk of bias
  • Relevance to the device's intended purpose and patient population
  • Sample size and statistical power
  • Follow-up duration

Data from poor-quality studies carries less weight. Document the appraisal systematically.

Stage 3: Analysis and synthesis​

Synthesise the available clinical data to answer:

  • Does the clinical evidence demonstrate that the device performs as intended (efficacy/effectiveness)?
  • Does the clinical evidence characterise the safety profile (adverse events, complications)?
  • Is the benefit-risk balance positive for the intended purpose?

Stage 4: CER writing​

Document the entire process and conclusions in the Clinical Evaluation Report.

Ongoing clinical evaluation: PMCF​

Clinical evaluation does not end when the device is placed on the market. Post-Market Clinical Follow-up (PMCF) is the proactive collection of clinical data from the marketed device to:

  • Confirm the long-term safety and performance of the device
  • Identify previously unknown risks
  • Identify emerging risks based on clinical evidence or adverse event data
  • Detect rare or delayed adverse events

PMCF is implemented through:

  • Registry participation
  • Post-market clinical studies (observational or interventional)
  • Systematic literature reviews (ongoing)
  • Structured follow-up of implanted patients

PMCF results feed back into the CER at each update cycle.

See Post-market clinical follow-up (PMCF) for full requirements.

Clinical evaluation by class​

The depth of clinical evaluation required scales with device risk:

ClassClinical evaluation expectations
Class IMinimal — literature review confirming safety; no clinical investigation typically required
Class IIaModerate — systematic literature review; equivalent device data usually sufficient; PMCF plan required
Class IIbSubstantial — systematic literature and device-specific data; clinical investigation may be required for novel devices; annual PMCF update
Class III / AIMDComprehensive — systematic literature, device-specific clinical investigation data often required; UKAB scrutinises CER; annual PMCF update mandatory
IVDPerformance evaluation (see Performance evaluation for IVDs)

Official references​

ReferenceDescription
UK MDR 2002, Schedule 1, ERs 1–3, 6Essential Requirements requiring clinical evidence
MEDDEV 2.7/1 Rev.4 (2016)Clinical evaluation methodology — MHRA-endorsed guidance
MHRA: Clinical evaluation guidanceMHRA's position on clinical evaluation
ISO 14155:2020Clinical investigations of medical devices for human subjects
EU MDR 2017/745, Annex XIVEU clinical evaluation requirements (detailed reference for NI market)