Clinical Evaluationkey elements of literature searching

A literature search is considered an organized search to find key literature on a topic. To complete a thorough literature search, a literature review involves critical analysis and the integration of information from several sources, as well as consideration of any gaps in the literature and the possibilities of future research. The initial steps are necessary for the planning of the literature search and review protocol.

  • Technical documentation and clinical evaluation form the basis of the assessment of medical device conformity.
  • A clinical evaluation is mandatory for medical devices in all risk classes.
  • Clinical evaluation is a process where all significant clinical data concerning a medical device is gathered and subsequently evaluated.
  • The Clinical Evaluation Report (CER) serves as a product and analyzes whether there is sufficient evidence to demonstrate product safety and efficacy.

A literature review consists of two phases: the literature search and the evaluation of the available literature, i.e.,

  • How to undertake a successful literature search
  • How to write a literature search and review protocol

In MEDDEV 2.7/1 rev. 4, Annex 5 talks about the literature search and literature review protocol as key elements. Through the literature search, we can find literature on the device under evaluation that includes the equivalent device and the state of the art, including alternative examination and treatment methods. There are three steps for the literature search.

Step One: Determine what should be found.

It is very important to understand that the literature search needs to cover two categories of data:

  • Clinical data on the medical device in question or its equivalent device and
  • Data for the state of the art may relate directly to the device in question and/or to equivalent devices, benchmark devices, and similar devices and technologies, as well as to the medical alternatives available to the intended patient population.

If a manufacturer possesses clinical data for the device, this is a definite plus. The literature is then considered together with the data to enable a consistent appraisal and overall analysis.

Step Two: Understand the goal

The goal is to identify published scientific papers (reviews, clinical trials, and meta-analyses) that hold valid results regarding the safety, performance, and clinical benefits of the medical device in question and the state of the art for the device. The literature search should be precise, detailed, and systematically documented. The selection of literature should be objective and justified, which means it should include all the relevant data, both favorable and unfavorable.

The selected papers should reflect the intended use of the device, and this should be kept in mind when considering writing a literature methodology, i.e., a literature search and review protocol.

Step Three: Write a Literature Search and Review Protocol

A literature search and review protocol should contain:

  • Research question
  • Databases that will be used
  • Terms that will be used
  • Inclusion/exclusion criteria
  • Search methods used in the literature evaluation
  • How the duplication of data from multiple sources will be addressed
  • How data integrity will be ensured (e.g., quality control or a second review of extracted data by an additional reviewer)
  • How each data source will be appraised and its relevance to the device in question
  • How the data will be analyzed and processed

Research Question

The research question should be consistent with the scope of the clinical evaluation and carefully constructed using the PICO method or its variations. The PICO method will help in literature searches, such as when looking for search criteria for the state of the art. Intervention; patient/population; comparison; outcome The PICO method is commonly used in evidence-based practice and is recommended by MEDDEV 2.7/1 Revision 4 for use in clinical evaluation literature searches.

MEDDEV 2.7/1 Revision 4, Annex 4, guides the selection of suitable literature databases. It recommends using PubMed, the Cochrane Library, Europe PMC, PDQ Evidence, Trip Database, and Google Scholar. So, we can find a list of other potential sources for literature and clinical data in the article. The use of boolean operators allows literature searches, which saves the trouble of reading non-specific literature sources. However, we can also use Boolean operators to expand the search, especially if we don’t find enough literature sources. The operators can be used to combine different search terms according to context. The most well-known Boolean operators are AND, OR, and NOT.

  • Combining terms with “AND” filters the results for entries that contain all the search terms.
  • Combining terms with “OR” filters the results to show entries that contain one of the search terms.
  • And combining the terms with “not” excludes entries with this search term from your search.


MEDDEV 2.7/1 Rev.4 is a useful technical guide for literature searches that will help to achieve the literature search and clinical evaluation. In MEDDEV 2.7/1 Rev. 4, there are requirements for literature searches. The publications were found during the literature search by using Boolean operators. It is also advisable to exclude irrelevant publications at an early stage. Also, in addition to the state of the art, one must at least evaluate the information on an equivalent device, thereby carrying out at least two searches.

About the Author

Mrs. A.J. Sony is a motivated, goal-driven, and committed professional who is currently employed by I3CGLOBAL as a junior consultant in CER documentation. Mrs. Sony has a master’s degree in pharmacology (M-pharm).