Evidence Based Medicine, Hierarchy of evidence

Evidence Based Medicine
Evidence based medicine (EBM) is an approach to medical practice that consists of the use of results of documented previous research in order to treat patients in the most accurate and efficient way possible. Even though modern medicine is profoundly based on empirical (scientifically proven by experiment) facts, Evidence Based Medicine extends further, rating the findings from the experiments by different measures (for example, the number of people the trial was performed on, the randomness of the testing etc.). This classification allows a researcher to yield the strongest, most reliable results one can work with. The results of randomized controlled trials and meta-analysis will be considered the strongest, most recommended evidence to rely on, while the researches that are considered to have “weaker” or results which are less credible will be case-controlled studies or experiments with an unknown origin.

The main concept of evidence-based medicine is to prove that medical practice should not be based solely on the treating physician’s personal knowledge or experience but it should be more definitely based on solid, reliable, carefully gathered evidence. This approach supports the belief that one may never fully know the extent of the clinician’s knowledge on a certain subject, nonetheless be able to assess it, and therefore the solid facts should always be the main guideline to treatment, whether discussing medical education, the treatment of individuals, or establishing policies that may concern whole populations.

When gathering medical evidence, the method of choice is the Scientific Method. It standardizes the gathering of evidence, regardless of the type of evidence, by following a strict set of steps. The goal of this method is to test a given theory (hypothesis).

Guidelines of Medical Based Medicine
EBM guidelines are essentially documents issued by respected medical society in the particular field (e.g. American Society of Hematology) that aim to guide decisions and criteria regarding practice, diagnosis, and decisions in various clinical instances. Modern medical guidelines are based on an examination of current evidence within the format of evidence-based medicine. Continuously updated, EBM Guidelines follows the latest developments in clinical medicine and brings evidence into practice.

Scientific databases
There is a huge amount of scientific evidence and the number is still increasing, therefore an abstracting and indexing services that serves for searching in the evidence have grown up in the last decades. The services are sometimes called scientific databases. The most important acientific databasesbstracting and indexing services in the field of medicine are following:
 * Web of Science (Web of knowledge) – general interest database
 * Scopus – general interest database
 * PubMed – medical database
 * Medline – medical database
 * Embase –medical database

Hierarchy of Medical Evidence and Evidence Pyramid
The hierarchy of medical evidence is the distinguishable levels of evidence that can be obtained through various methods, and placing them in an order based on their credibility. For any given topic, the highest level of evidence is not always obtainable in which case a researcher would move down the pyramid.
 * At the bottom of the pyramid is lab testing and animal research. While this is not necessarily an optimal method in order to validate a certain therapy, it can be used as an indicator about the adverse effects of a treatment, and may signal that the therapy will be injurious to the quality of evidence. In the middle of the evidence pyramid or case reports and case studies that outline treatment on patients, yet yield no verifiable evidence as they can only show causation, and not correlation. Furthermore, case studies use past medical documents to retrospectively look for evidence as opposed to cohort studies which prospectively follows a large number of patients in an attempt to find an outcome. In broad categories, all of the aforementioned should not be regarded as being of very high in credibility in clinical practice.
 * Randomized control trials is used to reduce bias and begins by selecting cases in to the two separate groups (it must be completely random - therefore "randomized" CT). The goal is to make two evenly distributed groups on which the drug effects make little difference based on individual factors and two obtain results that are not influenced by assumptions of those conducting the study.
 * Systematic review is the Review of the RCTs or other high-evidence articles and is regarded as the key in evidence-based medicine. It is high on the Evidence Pyramid and is classified as “filtered” evidence, having undergone analysis.
 * Meta-Analysis is the quantitative and statistical analysis of the data acquired in all different methods of testing throughout the research period. All results are compared, and all corresponding results are put together statistically to reach more conclusions. The stronger correlation between different methods about one topic, for example the hearts response to a drug, the more likely it is to be true. This is the highest level of evidence and conclusions can be drawn one this evidence has been acquired.

Clinical trials - Types of clinical trials
Clinical trials are research studies that evaluate the efficiency of new medical approaches. A study might, for example, try to provide better ways to prevent, screen for, diagnose or treat a disease.
 * Controled trial - the effect of the therapy is controlled by the control group (participants that do not recieve a treatment)


 * Randomized CT - randomization means that the participants are assigned into the groups (treated vs. placebo goup) randomly. So the patient does not know if he/she is treated or not and therefore they are not able to influence the outcome. Placebo is a substance similar in appearance to the experimental drug is used, not containing the active ingredients of the latter
 * Blinded or double blinded or tripple blinded CT - The participant or both the doctor and participant or all three the doctor, participant and statistician do not know how were the patients divided into the groups, so they do not know if the particular patient is in the treated group or in the placebo goroup
 * Multi-center; the study is carried out in multiple locations (e.g. in different towns or even in more than one countries)