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Evidence-based medicine (EBM) is a branch of medicine that emphasizes using clinical and research evidence in making decisions about patients. [1]]


Largely due to the work of a group of epidemiologists, such as Sir Austin Bradford Hill, Archie Cochrane, and Richard Doll.

Epistemology of EBM

The principles of EBM are founded upon the premise that medical knowledge grows at a faster rate than health care providers can absorb. To resolve this dilemma, the principles of EBM seek to concentrate the salient points from medical research, via systematic review and meta-analyses, into a more easily accessible format for health care providers with a scarcity of time.

To achieve the goals of EBM, the medical evidence must be evaluated. This evaluation is primarily based upon research study design parameters (population size, types of controls, analytic methodologies, etc.). The randomized-controlled trial is considered to yield the strongest evidence within medical research.

There exists a recognized delay between the time that medical research discovers a profound truth to the time this truth is actually applied within the clinical environment. The lag has been reported as up to 7 years. The reasons for this delay range from the systemic to the philosophical. Even with a summary of relevant research, many providers are still unable to allocate the necessary time to acquire and implement this knowledge. Some providers discount the entire premise of EBM. It is likely that some combination of time-constraints and knowledge management primarily contribute to this lag time.

EBM is awash in opportunities for Healthcare Information Technology solutions. Pattern-recognition and algorithm management are IT tools that may dramatically improve the collection of evidence and the application of consistent, high-quality health care services. A serious evaluation of where and how HIT can be inserted into the process of medical knowledge acquisition and application is urgently needed, as of 04/19/2006.

Evidenced Based Medicine (EBM) includes the use of the published, medical literature to guide medical practice. Inherent in this, is the ability to judge the quality of the medical literature, to understand what statements can rationally be made from the medical literature, to appreciate the strength of those inferences, and to realistically apply them to a particular patient or clinical situation.

The EBM Process can be summarized by four steps:

  1. Formulate a sensible, focused clinical question.
  2. Search the medical literature for evidence related to the focused, clinical question.
  3. Rate the quality of the available studies.
  4. Apply the evidence to a particular patient or clinical situation.

In the first step, the clinician must decide explicitly what patient population he or she is interested in, what tests, treatments, and alternatives he or she is considering, what the outcome of interest is (and how is it to be measured). These questions can be remembered with the mnemonic "PICO": Patient, Intervention(s),Comparisons, and Outcomes.

The second step of the EBM process is to search the medical literature. Aside from understanding the methods, strengths, and weaknesses of various search strategies and search engines, this step also involves looking for the highest level of evidence. In general, Systematic Reviews (not to be confused with general Review Articles) are considered the highest level of evidence, followed by Randomized Controlled Trials (RCT), then Case-Control Studies, followed by Expert Opinion and then, lastly, anecdotal evidence. More information on searching can be found in this Clinfowiki article http://www.clinfowiki.org/wiki/index.php/Searching_for_Evidence [2]

The third step--rating the quality of the available studies--involves a knowledge of research methodology that is important to make valid conclusions. For example (for RCTs): Was a control group used? Was assignment to an experimental vs. control group truly random? Were patients, treatment providers, and outcome assessors blinded to group assignment? What is the risk of a Type I or Type II error? What is the effect size? Or for Systematic Reviews: Was the literature review truly comprehensive (and how can you know)? Was the assessment of study quality rigorous and subjectively graded? Can numerical assessments be statistically combined (a "meta-analysis") to increase statistical power? The answer to these questions often depends on the particular parameters decided in the first step.

The last step of the EBM process is the ability to translate the ideal findings of carefully controlled studies to the less-ideal and less-carefully-controlled situation of a particular patient. What are the particular risks and benefits for this patient? What are his or her preferences? What are the costs, alternatives, and availability of particular treatments? Even for a statistically significant finding, is the effect size practically significant? Does the practitioner have the necessary skill or resources to deliver a treatment or to monitor the outcomes?

As medicine has continued to grow and become more complicated, the number of medical specialties has increased and their depth matures. At the same time, the amount and complexity of the medical literature has similarly grown. In this sense, Evidenced Based Medicine can be considered a burgeoning medical specialty, with the medical literature itself as the object of study.



HIT’s Role in EBM

The link below describes a process for building health science knowledgebases used by evidence-based decision support tools. This gives an expanded view of the processes corresponding to the quality metrics, practice guidelines, knowledge services and tools, and CQI feedback loops.

Evidence-based HealthCare Decision Support System

Registration of Randomized Clinical Trials

Randomized clincal trials are the primary method of testing the safety and efficacy of new medical treatments. Thus they are the foundation of evidence-based medicine, and they are critical in the creation of clinical guidelines. There is concern in the medical community about publication bias of clinical trial results. The results of many trials are never published, and positive results are more likely to be published than negative results. The American Medical Association has written

“Unfortunately, selective reporting of trials does occur, and it distorts the body of evidence available for clinical decision-making. … The case against selective reporting is particularly compelling for research that tests interventions that could enter mainstream clinical practice. Rather than a single trial, it is usually a body of evidence, consisting of many studies, that changes medical practice. When research sponsors or investigators conceal the presence of selected trials, these studies cannot influence the thinking of patients, clinicians, other researchers, and experts who write practice guidelines or decide on insurance-coverage policy.” (2)

In an effort to eliminate publication bias, the American Medical Association advocates mandatory registration of all clinical trials in public trial registries. To encourage this practice, the International Committee of Medical Journal Editors (ICMJE) requires researchers to register clinical trials in a clinical trial registry, such as ClinicalTrials.gov, as a condition of publication in their member journals. The ICMJE requires that general information about the trial, such as its hypothesis, outcome measures, schedule, target number of subjects, and funding source be entered into a registry. However, the ICMJE does not currently require that the results of clinical trials be published in a registry. (2)

Some in the medical community want to take the registration of clinical trials one step further – they want the results of clinical trials to be publically available in registries. They feel this step will “improve research transparency and will ultimately strengthen the validity and value of the scientific evidence base.” (4) Thus, there are efforts underway to store clinical trial results in registries, such as the WHO International Clinical Trials Registry. (4) There are also initiatives to store clinical trial results in registries in computer-understandable formats to allow easy querying about trials or results and to allow data mining.

One such initiative is the Global Trial Bank of the American Medical Informatics Association (AMIA). AMIA’s goal is to create “the world’s peer-reviewed repository of protocols and results from clinical trials of all types.” AMIA hopes to store results from trials conducted by universities, government agencies, and the pharmaceutical/biotechnology industry. Most importantly, the results in the Global Trial Bank will contain data coded using SNOMED-CT so that “decision support systems can directly access the knowledge over the Internet.” (1)

Another initiative is the Trial Bank Project created by Ida Sim of the University of California San Francisco. Dr. Sim stores the “design, execution and result information from randomized clinical trials (RCTs) directly into computer-understandable ‘trial banks’". The clinical trials data is organized into a hierarchical data schema. The schema is available for viewing at http://rctbank.ucsf.edu/ontology/outline/index.htm . In addition, the public can browse the design and results data for trials in the Trial Bank Project at http://rctbank.ucsf.edu/Presenter/. Dr. Sim is collaborating with JAMA and the Annals of Internal Medicine journals to store the randomized clinical trial results that they publish. (3)

Searching for Evidence

see Searching for Evidence

Pubmed’s new evidence based searching utility

On pop up windows during drug order entry displaying the latest evidence-based medicine articles from pubmed.

Statement of the problem: there is a lack clinician’s access to contextual information at the point of drug order entry in most CPOEs.

Background information: In the mid-1990s, PubMed introduced it’s search engine. This search engine is a web-based information portal for all types of medically-related journals, which now includes a category for evidence based medicine (EBM). PubMed later introduced limits and automatic web service interfacing to view returns via a web page from a program written in java. Thus, it is possible to build a program that would return the latest evidence based medicine articles limited to those published in the last year to the clinician automatically during drug-order entry on Windows and Unix based CPOE clients. This may be useful in cases where a clinician has incomplete knowledge of a drug’s important recent studies and access to the articles is only provided through a button on the CPOE entry screen.

A description of any alternatives: Alternatives are limiting drug decision support to guidelines.

Major conclusions: With Pubmed’s new evidence based searching utility, one may ask, is it worthwhile to put up a link to PubMed articles for the most recent year during drug order entry? This would be a teaching aid as well, given that only the most recent EBM article would be returned. This would be useful in case of perhaps, when the entering clinical is a pharmacist.--Crawford 18:59, 5 November 2007 (CST)


  1. American Medical Informatics Association (2006). Global Trial Bank. http://www.amia.org/gtb/. Accessed on May 20, 2007.
  2. DeAngelis, C., Drazen, J., et al. (2004). Clinical Trial Registration – A Statement from the International Committee of Medical Journal Editors. Journal of the American Medical Association. September 15, 2004, Vol. 292, No. 11. Available at http://jama.ama-assn.org/cgi/content/full/292/11/1363 .
  3. Sim, I. (2007). The Trial Bank Project. http://rctbank.ucsf.edu/ . Accessed on May 20, 2007.
  4. World Health Organization (2007). International Clinical Trials Registry Platform. http://www.who.int/ictrp/en/