Evidence Based Medicine, Hierarchy of evidence
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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
  • Ombase –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.

  • Randomized CT - randomization means that the patients are divided 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.
  • Blinded or double blinded CT - The doctor or both the doctor and statistican do not know how was 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

Cohort Studies

Any group of people linked in some way is a cohort. In cohort studies researches follow and observe a group of patients, over time, who are undergoing a certain treatment or have an exposure. Researchers then compare the patients’ outcomes to a similar group who have not been exposed. An example of a cohort study would be, following a group of children from their birth, and record various information (exposures) about them. [5]

Clinical trials may be categorized according to various criteria.

Firstly, according to their objectives & the way they are organized:

  • Interventional (treatment) trials; aiming to test methods of treatment not yet approved
  • Prevention trials; attempting to prevent particular conditions or reoccurring of such
  • Observational trials; investigating health issues in greater groups of people (participants provide information, blood samples etc.)
  • Diagnostic and screening trials; attempting to find new and more effective ways of detecting and diagnosing medical conditions (e.g. better and more effective tests/procedures)

Secondly, according to the group of people likely to benefit from the study:

  • Therapeutic; the investigated treatment is expected to benefit the participants (as in the case of a drug trial)
  • Non-therapeutic; the trial is unlikely to benefit the participants but will yield information which could contribute towards further understanding a condition and future development of new treatments

Finally, according to way of organization that could affect the participants (especially regarding the inclusion of a placebo group). The most common results of this classification are:

  • Randomized; participants are assigned into separate groups randomly
  • Placebo; a substance similar in appearance to the experimental drug is used, not containing the active ingredients of the latter
  • Add-on; all participants receive existing therapy. Then, some receive the experimental drug, while others do not, or receive a placebo
  • Open label; both researchers and participants are aware of the administered drug
  • Blind; the participants are not aware of whether they are in the treatment or placebo group
  • Double blind; neither participants nor researchers know which participants are in the treatment and which in the placebo group, until the end of the study
  • Single-center; the study is carried out in a single location
  • Multi-center; the study is carried out in multiple locations (e.g. in different towns or even in more than one countries)[2] Controlled; a comparison (control) group is included. The latter receives a placebo, a different treatment, or no treatment at all.[3]


References

http://www.fao.org/docrep/005/AC665E/ac665e06.htm [1] produced by natural resources management of environment department.

Evidence-Based Medicine Working Group (November 1992). "Evidence-based medicine. A new approach to teaching the practice of medicine". JAMA. 268 (17): 2420–5 Epling J, Smucny J, Patil A, Tudiver F (October 2002). "Teaching evidence-based medicine skills through a residency-developed guideline". Fam Med. 34 (9): 646–8 https://www.essentialevidenceplus.com/product/features_ir.cfm?show=ebmg http://onlinelibrary.wiley.com/book/10.1002/0470057203 http://www.merckmanuals.com/professional/special-subjects/clinical-decision-making/evidence-based-medicine-and-clinical-guidelines http://ktdrr.org/ktlibrary/guidelines.html Center on Knowledge Translation for Disability and Rehabilitation Research (KTDRR) is housed at SEDL. Copyright ©2016 SEDL, an affiliate of American Institutes for Research.

https://www.nih.gov/health-information/nih-clinical-research-trials-you/basics.

Council of Europe. Developing a methodology for drawing up guidelines on best medical practice. Recommendation Rec(2001)13 and explanatory memorandum. Strasbourg: Council of Europe Publishing, 2002 Burgers JS, Grol R, Klazinga NS, Mäkelä M, Zaat J, for the AGREE Collaboration. Towards evidence-based clinical practice: an international survey of 18 clinical guideline programs. Int J Qual Health Care 2003 Wilson W; Taubert KA; Gewitz M; et al. (October 2007). "Prevention of infective endocarditis: guidelines from the American Heart Association" Fang Gao Smith, FRCA MPhil MD Jeffrey L Tong, FRCA John E Smith Continuing Education in Anaesthesia, Critical Care & Pain | Volume 6 Number 4 2006 © The Board of Management and Trustees of the British Journal of Anaesthesia [2006]

Darrel W, Krueger Library, In Libris Libertas, Winona State University, http://libguides.winona.edu/c.php?g=11614&p=61584 University of California, San Francisco Library and Center for Knowledge Management Content adapted with permission from Connie Schardt of the Duke University Medical Center Library. June 2006

Moher D,Hopewell S, Explanation and elaboration: Updated guidelines for reporting parallel group randomized trials, 2010

[1] https://medlineplus.gov/clinicaltrials.html U.S. National Library of Medicine, National Institutes of Health, 2016, [2]http://www.alzheimer-europe.org/Research/Understanding-dementia-research/Clinical-trials/Types-of-clinical-trials Alzheimer Europe, 2009 [3]https://www.cancer.gov/publications/dictionaries/cancer-terms?cdrid=44014 National Institutes of Health, National Cancer Institute

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