Literature Route
General Information
According to guideline 93/42/EEC, it is possible to base a clinical evaluation on data collected in clinical studies as well as on published data about comparable devices and medical areas of treatment.
The latter possibility, which permits a clinical evaluation via the literature route, offers a save and efficient way of assessing a product's risks and benefits in the context of scientific publications and data for many clinical devices. For implantable or class III devices, clinical investigations are required by EC rules unless it can be duly justified to rely on existing clinical data alone. Additionally, it is possible to use data from pre-clinical evaluations to assess a product's clinical features.

For devices derived from existing products, but also for new and innovative products based on established medical and technical procedures, the option of clinical evaluation via the literature route should be considered thoroughly. If the medical device's conformity with guideline 93/42/ECC can be established
Criteria on the basis of data available via literature research, ethical aspects are another important factor in the decision whether further clinical research is necessary
(compare MEDDEV 2.7.1 respectively NB-MED/2.7/R1-3).

Data Sources The actual clinical evaluation of data follows the process of data collection. This collection includes all kinds of clinical data, published data in scientific literature as well as un-published data and results of clinical research, and analyses these critically.


Product Equivalence

Conformity to EU Guidelines
Selection of Literature Data
In order to guarantee that data a clinical evaluation is based on is relevant and can be used regarding the medical device in question, the decision about using the literature route has to take two main factors into account. First of all, the equivalence of the products concerned in the publications has to be established in relation to the product whose conformity is to be assessed. An evaluation of clinical data gathered through literature research for equivalent devices is permitted if an equivalency to the medical device in question can be established. This equivalency must be documented on a technical, biological and clinical level. Second of all, it has to be ensured that the data available are actually appropriate for showing the product's conformity regarding relevant requirements of guideline 93/42/ECC. This equivalence includes clinical application as well as functionality or properties of the materials used in the medical device. MEDDEV 2.7.1 requires demonstration of clinical, technical and biological equivalence of the procedures examined in the literature in relation to the object of a clinical evaluation.

Relevance of Literature
When selecting literature for the clinical evaluation of a medical device, it is important to weigh relevant scientific publications by their information content. Depending on how complex, dangerous or effective the method in question is, different requirements have to be met by the literature used for the evaluation. Generally speaking, a clinical evaluation should not be based on individual case reports, accidental findings, unproven opinions or on research without clear scientific methodology. Current EC guidelines emphasise the importance of a formalised and systematic approach to literature appraisal. This requires the implementation of a specific protocol for literature research as well as a thorough assessment of each publication's quality by medical experts.

Level of Evidence
for Clinical Studies
The German Physician’s Central Office for Quality Assurance (ärztliche Zentralstelle für Qualitätssicherung, ÄZQ) has devised a scale to assess the evidence level of clinical studies. This scale has five different levels with I being the highest and IVb the lowest level of evidence.
  • Level I: There is sufficient proof of effectiveness from systematic reviews (meta analyses) of several randomised controlled trials. 
  • Level II: There is proof of effectiveness from at least one randomised controlled trial. 
  • Level III: Proof of effectiveness from methodologically sound, well designed trials without randomization.
  • Level IVa: Proof of effectiveness in several clinical studies.
Level IVb: Expert opinion based on clinical experience or reports by expert committees.

Author's Qualification The author of a clinical evaluation as well as his methodology have to comply with precise criteria. In addition to medical knowledge, it is important for the author to be qualified for the evaluation of technical processes. The literature he consults has to be state of the art regarding medical procedures as well as technical requirements. Additionally, all relevant publications - both favourable and unfavourable - have to be incorporated into the analysis. In the clinical evaluation, the author has to illustrate and make transparent the methodology for the selection of literature as well as the kind of study or trial referred to in the report.

Application Risks

Risik Comparison
Evaluation of Risks
The clinical evaluation evaluates the medical effectiveness and safety of a medical device as well as possible risks. In the risk analysis, several kinds of potential dangers are distinguished. Firstly, there are risks which are part of the medical procedure, in whose context the medical device is being used.
An example would be a stent for treating vascular stenosis, where the risks related to the puncture site,The application of contrast agents and of analgesitics / sedatives are all taken into account. Additionally, these risks in combination with other alternative or competing forms of therapy are evaluated. Also, when evaluating a novel, minimally invasive procedure it is necessary to compare it to conventional established procedures.

Product and Application

Conclusion of the Clinical Evaluation
In a clinical evaluation, the particular benefits of the product whose conformity is to be established, are compared to the related risks and the advantages for patients, respectively users, are described. In doing this, all relevant features of the product itself as well of the clinical context of its use, are taken into account.

Final Evaluation A clinical evaluation ends with a conclusion, which illustrates the benefits of using the medical device according to its purpose in connection with the results of the risk analysis, the technological state of the art, clinical standards as well as the knowledge obtained through extensive literature research.

Clinical Evaluation as Part of the Technical Documentation
The clinical evaluation of medical data is usually conducted in the final stages of the technical documentation, this means after design processes, several stages of development, risk analysis etc. have been completed and compiled. The clinical evaluation is primarily based on these other sections of the technical
Risk Management documentation. Thus, it also assesses the consistency between the individual documents and the current state of knowledge in science and technology. The clinical evaluation for example ensures the sufficient documentation of all relevant risks of a medical device, which were described in scientific literature.If new risks are identified in the clinical evaluation, they have to be considered in risk management as well as technological R&D processes.

User Documents The same applies to the user documents for the medical product in question, which play a significant role in the clinical evaluation since they not only instruct the user about the correct application or operation of the product, but also have to provide him with adequate information about possible risks and dangers in using it.

The clinical evaluation thus serves to connect the content of the different sections of the technical documentation; at the same time it is an important source of information for the technical documentation itsef by providing relevant data and information as part of a feedback process.