Evidence-based medicine

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Evidence-based medicine ( EbM ), borrowed from English evidence-based medicine "on empirical evidence-based medicine", is a more recent development in medicine that expressly demands that patient-oriented decisions , if possible, on the basis of empirically proven medical treatment Effectiveness should be taken. The scientific informative value of clinical studies is described by evidence levels . Evidence-based medicine is intended to establish “patient-centered science”.

The name was coined in the early 1990s by Gordon Guyatt (* 1953) from David Sackett's group at McMaster University , Hamilton, Canada, in the Department of Clinical Epidemiology and Biostatistics . The concept was first published in 1995 in the German-speaking area, although the authors succumbed to a false friend when it was translated into German : While evidence in English has the meanings 'proof', 'evidence', 'note' or 'testimony' depending on the context, is the meaning of evidence in German Obensichtlichkeit (which requires no proof) (English: obviousness ). Therefore, it was suggested to use the term evidence- oriented medicine in German , but this did not catch on. In 2000, “ evidence-based guidelines ” were introduced into the German Social Security Code ( Sections 137e, 137f, 137g, 266 SGB ​​V , Structured Treatment Programs for Chronic Diseases).

Definition and application

Evidence-based medicine (EBM or EBM) was originally defined as the "conscientious, explicit and careful use of the best evidence currently available to make decisions about the care of an individual patient". EbM is therefore based on the current state of clinical medicine on the basis of clinical studies and medical publications that substantiate or refute a fact - the so-called external evidence .

In EbM clinical practice, this means integrating individual clinical expertise with the best available external evidence from systematic research; it also includes patient preference .

EbM can also include renouncing therapy, i.e. H. knowing when not (offering / suggesting) therapy is better for the patient than offering / suggesting a particular therapy. A frequently cited example is prostate cancer in old men: Depending on age, life expectancy and the stage of development of the cancer, not treating it is often the best decision.

Building on this evidence-based individual decision for the individual patient ( Evidence-based individual decision , EBID), the term EbM is also used in so-called Evidence-Based Health Care (EbHC). Here the principles of EBM are transferred to the organizational and institutional level, that is, a treatment recommendation is not determined for individual patients, but for a group of patients or for an entire population; Treatment recommendations, guidelines , guidelines or regulations are derived from the results of the research . EbHC can be used in all areas of health care; Decisions on how to manage the health system can also be based on their results.

For the field of dentistry - in analogy to EbM - the term “Evidence-based Dentistry” (EbZ) was established.


Evidence-based medicine requires not only clinical expertise (i.e. bedside expertise) from the doctor , but also the knowledge of how to acquire the results of current scientific research, how to interpret and apply them. Expertise is also required when talking to the patient, especially when discussing the possible benefits and risks of the various diagnosis and treatment options. Informed consent should be sought .

The implementation of EbM in practice means the integration of individual clinical expertise with the best possible external evidence from systematic research in a multi-stage process. A relevant, answerable question is derived from the clinical case. This question is used to research the medical literature. The researched literature must now be critically assessed with regard to its validity and usefulness (evidence). The selected and assessed evidence is then applied to the individual case.

All of these steps require practice, especially literature research and evaluation. However, since the entire medical knowledge is currently doubling every five years, even the practiced doctor is increasingly overwhelmed to determine what is important for him in the abundance of knowledge and knowledge. EbM-oriented organizations try to remedy this by using systematic evidence research and evaluation to find solutions to relevant, often subject-specific questions, in order to make the results from clinical research more transparent and easier in everyday practice.

Instead of using the original article (the primary literature) as in the classic EbM approach, the doctor uses secondary literature and systematic reviews for which the evaluation according to EbM criteria has already been made. The aim here is the synthesis of all relevant articles from the primary literature so that the search for practical everyday life can be carried out as quickly and specifically as possible. These reviews also form the basis for so-called Health Technology Assessments (HTA, in English: Technology Assessment in Medicine) and for evidence-based guidelines . One of the most important organizations for the creation of such systematic reviews is the Cochrane Collaboration .

EbM is a scientific method to evaluate the quality of the published medical data and thus to improve it. The EbM does not itself deal with the implementation of clinical studies, but with the systematic use of its results. In order to move from the evidence to the recommendation, different classification systems were developed - following EbM criteria. The external evidence is hierarchically sorted according to validity criteria in evidence classes which, in addition to the quality of the individual studies, include the entirety of the evidence on a question. Other classification systems extended the hierarchy of evidence to the requirements of different questions, the consideration of weaknesses in the execution of individual studies and inconsistencies between several studies, for example the classification system of the Center for Evidence-based Medicine in Oxford. Quality measurement tools such as the Jadad scale can be used to assess the quality of clinical trials . They check the formal quality of the conduct of a study, not the results themselves - however, conclusions about the quality of the results can be drawn from the study quality.

The division into classification systems is important in order to be able to adequately assess the benefits and risks of treatments (including benefits and risks of non-treatment). In addition to the assessment and classification of completed clinical studies, EbM principles can also be used in advance, i.e. H. during the design of clinical trials. Well-planned, high-quality, randomized, controlled, double-blind clinical studies with a sufficiently large number of patients meet the requirements for later classification according to EbM criteria. Such planning prevents wasteful use of money and resources.

In order to standardize the different classification systems and to take additional aspects such as relevance and feasibility into account, an international working group, the “GRADE Working Group”, has been establishing a new system since 2000. The GRADE system (Grading of Recommendations Assessment, Development and Evaluation) for evaluating the evidence and formulating recommendations has gained international importance and is supported by the WHO, the Cochrane Collaboration and many guideline organizations.


The idea of ​​evidence-based medicine can be traced back to the concept of medical arithmetic developed by British doctors in the 18th century . The name can be found for the first time in the article An Attempt to Improve the Evidence of Medicine by the Scottish doctor George Fordyce, published in 1793 .

One of the first controlled clinical trials was carried out in the UK. As early as 1753, James Lind published the results of his attempt to treat scurvy with oranges and lemons. In the German-speaking area, the Hungarian doctor Ignaz Semmelweis (1818–1865), who worked in Vienna, was the first authorship for the introduction of “systematic clinical observation” into medical research (1848).

The founding of modern EbM goes back to David Sackett's working group in the Department of Clinical Epidemiology and Biostatistics at McMaster University in Hamilton, Canada, where David Sackett has been the founding director of the department since 1968. Clinical Judgment by the American physician and mathematician Alvan R. Feinstein , published in 1967, and the book Effectiveness and Efficiency: Random Reflections on Health Services by the British epidemiologist Professor Archie Cochrane , published in 1972, led to an increasing acceptance of clinical epidemiology and controlled studies during the 1970s and 1980s Years and paved the way for the institutional development of EbM in the 90s. Cochrane's efforts have been recognized by naming an international network for evaluating efficacy in medicine - the Cochrane Collaboration  - after him. However, Cochrane himself did not live to see the founding of the EbM movement and Feinstein developed into one of its sharpest methodological critics.

The introduction of evidence-based medicine into surgery was also an act of emancipation from hierarchical structures.


The spread of EbM in the German-speaking area has been significantly promoted by the institutionalization of the German Network Evidence-Based Medicine (DNEbM e.V.). The aims of this specialist society are the further development and dissemination of the theory and practice of evidence-based medicine.

EbM is also taught in many universities. However, the implementation of this doctrine from theory into practice is still controversial. It is now known that practical courses (demonstration of EbM research and the practical application of EbM with individual patients) would lead to better teaching results.

In addition to textbooks, there is a freely accessible English-language series by the Canadian Medical Society.

Opposing positions

The following criticisms of evidence-based medicine are listed:

  1. Evidence-based medicine emphasizes the importance of randomized, controlled trials (RCTs) that allow reliable conclusions to be drawn about causal relationships. However, causalities can remain unexplained for a long time if evidence is not yet available.
  2. In observational studies and other research designs - sometimes the only way to investigate facts at all or with sufficient external validity - correlations are often used, and sometimes also secured relationships. Sufficient statistical certainty is required to derive evidence from this. In the opinion of critics, this is often not formally achieved.
  3. Meta-analyzes that are sponsored by pharmaceutical companies are often rated false positively. Evidence of the critical analysis of such meta-studies is required.
  4. With methodological considerations - in particular the problem of the heterogeneity of the objects of investigation - Alvan R. Feinstein justifies his criticism of the technique of meta-analysis as a source of clinical evidence.
  5. The publication bias contributes to the fact that studies with negative effects are published less often. This is why meta-analyzes that are not sponsored by pharmaceutical companies often achieve false-positive ratings.
  6. The ideological exaggeration is criticized. “'Evidence-based medicine', if it is correctly understood, describes something that goes without saying, namely the consideration of scientific principles in diagnostics and therapy. The term is currently not used that way, but is given an unfounded special position. ”( Wichert , 2005, p. 1569).
  7. From an epistemological point of view, criticism was made of the evidence concept on which the EbM is based. This is problematic because there is no room for an element of the “explanatory connection” (in the sense of Peter Achinstein ) between the evidence and the hypothesis to be proven. Such a connection is postulated in order to avoid logical problems of probabilistic concepts of evidence.

The effect of the EbM concept can be applied with a considerable delay if too few evidence and studies are available. For example, EbM is not as advanced in pediatrics as z. B. in oncology and cardiology . The main reason for this is that large controlled clinical trials in pediatrics are often not carried out or are difficult to carry out in themselves. As a result, there is not enough “evidence” available, as would be necessary for a reliable assessment. Instead, one has to rely on the “evidence” (that is, what is in front of one's eyes). However, this statement does not apply to all areas of pediatrics, e.g. B. not for pediatric hemato-oncology.

With regard to his personal decision, the individual patient depends on the information that he has at his disposal. In the case of acute treatment in particular, however, there is little time to transmit this information, so that the patient remains dependent on the treating doctor. The only alternative for the patient is to change the doctor, if no other choice is offered among different therapies. The EbM criteria are therefore not applicable to all areas of medicine.

A tightrope walk can also represent too narrow an interpretation of EbM. There are issues that have been clarified for a long time, but for which there is insufficient evidence in the sense of the EbM. As an illustration, the so-called Vipeholm study of 1954 was the first and so far the longest investigation into the cause of caries by sugar. For example, the breakthrough in ciclosporin treatment in immunosuppression after organ transplantation was so rapid that there are only relatively few studies of high evidential value to compare with the previously established scheme ( cortisone & azathioprine ). If the results are highly unambiguous (ie high “evidence” in the sense of the German word meaning), further prospective randomized comparative studies are prohibited for ethical reasons alone; the fact that there is insufficiently reliable evidence on a question must therefore not be interpreted in such a way that it should be answered negatively. In this context, it is also stated that good evidence is not feasible or too cumbersome in many areas of medicine. Almost all medical acts that are completely undisputed (ie “consensus-based” in German) are not evidence-based (ie not “evidence-based”) and never would be. The lack of proven benefit and lack of benefit are not the same thing.

The downside of an unsecured interpretation of EbM can in turn lead to inconsistent application. It also happens that EbM is not consistently applied in practice in areas of medicine or in countries where it is actually largely accepted.

Other areas of application

In the meantime, attempts have been made to transfer the concept of evidence-based knowledge to other areas such as psychotherapy , education and business informatics. There is also a critical discussion on this.


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  • Definitions and instruments of the German Network for Evidence-Based Medicine

See also

Web links

Individual evidence

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  6. § 137f SGB V
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