Choosing the right primary criteria in a clinical trial is a strategic step that determines not only the scientific success of a study, but also its chances of obtaining marketing authorization and reimbursement by healthcare systems. A poorly defined criterion can jeopardize years of research and considerable investments. Conversely, a relevant and validated criterion increases the value of the results, credibility with regulatory agencies, and confidence from prescribers and payers.
Why is the primary criteria so crucial?
The primary criteria in a clinical trial is the main parameter chosen to measure the effectiveness of a treatment or a medical device. It serves as the reference to judge whether the drug or the device provides a real benefit to patients. Without this anchor point, results may be challenged or even rejected by authorities such as the European Medicines Agency (EMA), the Food and Drug Administration (FDA), or the Notified Bodies responsible for medical devices.
In practice, the primary criteria must meet three conditions:
- Clinically relevant– it should reflect a tangible benefit for the patient (survival, reduction of symptoms, improvement of quality of life or function).
- Objectively and reliably measurable – using validated and reproducible tools.
- Sensitive to change – able to capture the treatment or device effect within a reasonable timeframe.
Concrete examples of primary criteria
The choice of the primary criteria varies depending on the product and therapeutic area:
- For drugs:
• In oncology: overall survival or progression-free survival.
• In cardiology: major cardiovascular events such as myocardial infarction or stroke.
• In rare diseases: internationally validated clinical scores. - For medical devices:
• For a cardiovascular implant: technical success rate of implantation, absence of reintervention at 12 months.
• For a diagnostic test: sensitivity and specificity compared to the reference standard.
• For an orthopedic implant: bone consolidation, functional improvement (for example WOMAC score).
• For a surgical hemostatic device such as PuraStat®: achievement of hemostasis within a defined timeframe, or reduction in the need for tamponade or complementary procedures.
These examples show that the primary criteria must always be adapted to the nature of the health product being evaluated and its real clinical use.
The role of health authorities and reimbursement
The European regulation EU 536/2014 on clinical trials of medicines, and regulations EU 2017/745 and 746 for medical devices, emphasize the importance of clear and harmonized protocols when defining evaluation criteria.
- The EMA publishes therapeutic guidelines with precise expectations by disease area: EMA guidelines on clinical trials.
- In the United States, the FDA provides disease-specific guidance documents: FDA Clinical Trial Endpoints Guidance.
But the primary criteria is also decisive at the reimbursement stage. In France, for example:
- For drugs, the Haute Autorité de Santé (HAS) assesses the Service Médical Rendu (SMR) and the Amélioration du Service Médical Rendu (ASMR).
- For medical devices, the HAS evaluates the Service Attendu (SA) and the Service Rendu (SR).
👉 More information: HAS – Evaluation of medical devices • HAS – Evaluation of drugs
A solid and relevant primary criteria is therefore essential to demonstrate a clear clinical benefit, and thus obtain reimbursement. Without it, even an authorized drug or device may remain difficult for patients to access.
The situation is similar in many countries: reimbursement bodies such as the NHS in the United Kingdom or the G-BA in Germany rely heavily on the trial’s primary criteria to assess therapeutic and economic value.
Pitfalls to avoid
One of the major risks is selecting a criterion that is too intermediate (such as a biomarker or an isolated technical parameter) which may not reflect actual clinical improvement. This may convince researchers, but not reimbursement agencies.
Another pitfall is defining multiple primary criteria simultaneously. This dilutes statistical power and complicates the interpretation of results. Regulatory agencies consistently prefer a single primary criteria, supported by secondary criteria that enrich the analysis.
The importance of stakeholder alignment
Defining the primary criteria in a clinical trial requires concertation between researchers, biostatisticians, patients, regulatory authorities and payers. For both medical devices and drugs, it is essential to anticipate the expectations of economic decision-makers early in the process.
A criterion focused on real patient impact (quality of life, autonomy, reduction of severe events) is far more likely to be recognized by public payers. This alignment ensures that clinical innovation also translates into patient access.
Towards more innovative criteria
With the rise of digital health, new tools are emerging to enrich the definition of primary criteria:
- Connected sensors providing continuous patient monitoring.
- Real-time quality-of-life scoring systems.
- Real-World Evidence (RWE), integrating routine practice data into clinical evaluation.
These innovations could transform how primary criteria are defined, making them more reflective of patient experience and producing data useful to both regulators and payers.
👉 Example of a patient-centered approach: European Patients’ Academy on Therapeutic Innovation (EUPATI).
Conclusion
Choosing the right primary criteria in a clinical trial is not a technical detail: it is a strategic choice. It determines not only the scientific and regulatory validity of the results, but also the ability of a drug or medical device to be reimbursed and thus truly accessible to patients.
In today’s competitive environment, where every country seeks to balance innovation with healthcare system sustainability, the primary criteria has become the key intersection between science, regulation and public health.
