Evidence-based medicine (EBM)

There is often a number of different methods, medication and therapies available to examine and treat sick people. The aim of evidence-based medicine is to identify investigative methods and treatments that are high quality and effective.

“Evidence-based” means that an investigative method or treatment is selected and implemented, and recommendations made, based on evidence. In healthcare this evidence is documented results of medical research. These complement medical practitioners’ expert knowledge and practical experience.

In evidence-based medicine doctors often use findings produced by professional bodies, such as medical guidelines. These are recommendations on the investigation and treatment of specific conditions that have been developed systematically based on scientific findings.

Other summaries of the latest research (systematic reviews or other evidence syntheses) are used to support the work of medical practitioners. This is because doctors and therapists do not have the time needed in their routine practice or hospital work to go through each individual set of research findings.

Instead, they apply the findings gathered together in, for example, guidelines or evidence syntheses, to their patient’s specific problem.

Evidence-based medicine also takes account of patients’ wishes and values: doctors explain the advantages and disadvantages of various treatment options to patients so they can make a shared decision. 

Medical research uses a number of different type of scientific studies. These range from experiments or observations to comparative studies. In terms of evidence-based medicine, they are not all equally suitable for drawing conclusions as to suitable investigative or treatment procedures.

Case reports, for example, are only of limited use. This is because they involve an observation of individuals or small groups of people. An observed effect will not necessarily apply to other people as well. 

In cross-sectional studies groups of people are investigated at a specific point in time. However they are also unsuitable for identifying causes and effects: for example, a study that produces the observation that people eat a lot of ice cream in August and a lot of people get sunburnt does not mean that the sunburn is caused by people eating a lot of ice cream or vice versa. However cross-sectional studies can act as a sort of snapshot to show how often a disease occurs in a group at a specific point in time.

Randomized controlled trials (RCT) are highly suitable for demonstrating effects, benefits and safety of investigative or treatment procedures. In this sort of trial participants are randomly divided (“randomized”) into two or more groups. One group receives the intervention under investigation over a long period, for example headache tablets with a new active ingredient. Another group acts as the control and receives a sham intervention (placebo). If the aim is to find out whether the new active ingredient is better than those used previously, another group will receive the current usual treatment. Comparing the results from the groups provides information on how great the benefit of the new treatment is and what side effects occur and how often they occur. 

Since there are numerous research studies of this type and their number is increasing rapidly, the results of multiple clinical trials on specific questions are gathered together in summaries, for example “What active ingredients are best for migraine?” 
Researchers conduct systematic reviews to combine the results of individual studies into this question. Meta-analyses involve analyzing the findings from these studies to work out the overall result and produce a scientifically sound statement.

In evidence-based medicine the following steps are taken to come to a decision in favor of or against a specific medical intervention:

• First, the medical question is formulated, for instance “Does active ingredient X provide more headache relief than active ingredient Y?”
• This is followed by a comprehensive literature search to identify suitable clinical trials on this question.
• Sources are subjected to a critical appraisal: are they representative? How credible are the results? Are there any flaws in the methods used? Can the results be applied to other patient groups?
• The insights gained are then put into practice based on each individual patient’s situation.
• Finally, the outcome of the procedure is subjected to appraisal and adjusted as necessary: evidence-based appraisals of clinical practice and new therapeutic approaches provide an important basis for patient safety.

In practice, evidence-based medicine is used by doctors to supplement their own experiences with findings from the latest research. They will usually do this by consulting aids such as medical guidelines or reviews of the latest research. 

They then relate these to their patient’s situation. They arrange an appointment with the patient to explain the options available and the advantages and disadvantages of a specific treatment or investigation.

What are medical guidelines?

Guidelines help doctors to make the right decisions on specific medical issues. A guideline on a specific subject is developed by a specially convened panel of experts made up of medical research associations and, where appropriate, other professionals and patient organizations. The panel issues recommendations based on scientific findings in line with a specified procedure. The recommendations are updated regularly.

In Germany, guidelines are developed under the coordination of the Association of the Scientific Medical Societies in Germany (AWMF). They are divided into the following categories: 

• S1 – A group of experts provides a recommendation without following a formal procedure.
• S2k – A specially selected panel follows a formal procedure to arrive at a joint recommendation (“k” stands for consensus).
• S2e – An evidence-based guideline based on a systematic search, selection and critical appraisal of scientific evidence (“e” stands for evidence).
• S3 – This is the highest level of guideline and combines the qualities of the S2k and S2e guidelines.

Strictly speaking, only S2e and S3 categories are evidence-based and rely on scientific findings that have been systematically reviewed by experts.

Patients are involved in evidence-based medicine: they can share the decision on what treatment they prefer and what treatment they reject. This is important because people do not all have the same wishes and goals.
This type of decision is easier to make if you are well informed. This includes reliable answers to questions such as “What treatment options are there?”, “Which therapy is the most suitable for me?”, “What are the risks?” or “Do I have an alternative?” 

For informed decision-making it’s important for doctors to explain potential treatment options and their consequences. Other important sources of information include advice centers such as the Independent Patient Advice Service for Germany (Unabhängige Patientenberatung Deutschland – UPD), self-help organizations, health insurance providers and reliable health information on the internet. All this information contributes to good health literacy that helps people to cope better with their condition.

Clear patient guidelines are available at patienten-information.de.

The German Health Competence Network (DNGK) provides a list of reliable health portals on the internet. 

Comprehensive explanations of evidence-based medicine and the procedure are provided on the website of the German Evidence-Based Medicine Network (Deutsches Netzwerk Evidenzbasierte Medizin e.V.).

The Association of the Scientific Medical Societies in Germany (AWMF) provides a summary of medical guidelines and patient guidelines.

Guidelines and patient guidelines on cancer are also available on the website of the German Guideline Program in Oncology which is run jointly by the AWMF, the German Cancer Society (Deutsche Krebsgesellschaft) and the German Cancer Aid Foundation (Stiftung Deutsche Krebshilfe).

More evidence-based information on common diseases, diagnoses and health-related issues, as well as information on evidence-based medicine, is provided by the Institute for Quality and Efficiency in Health Care (IQWiG) on the https://www.gesundheitsinformation.de/ website.