Evidence-based medicine

Evidence-based medicine is defined as "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.". An alternative definition is "the process of systematically finding, appraising, and using contemporaneous research findings as the basis for clinical decisions". Better known as EBM, evidence based medicine began being discussed in the early 1990s.

This article discusses the field of evidence based medicine. Background in the history of medicine, clinical epidemiology, and the ethics of medical experimentation is included. Evidenced-based practice is not restricted to medicine among the health sciences, dentistry, nursing and other allied health science are adopting "evidence based medicine" as well.Evidence-Based Health Care or evidence-based practice extends the concept of EBM to all health professions, including purchasing and management [1].

Why do we need evidence-based medicine?

Why should such an approach to clinical medicine merit its own name, let alone another acronym in the medical literature? Don't physicians ordinarily conscientiously and judiciously use scientific evidence in treating patients? Isn't that simply routine medical care?

In fact, most of the specific practices of physicians and surgeons are based on traditional techniques learned from their seniors in the care of patients during training, that are modified with personal clinical experience and information gleaned from the medical literature and continuing education courses. Although these practices almost always have a rational basis in biology, the actual efficacy of treatments is rarely explicitly proven by experimental trials in people. Further, even when the results of experimental trials or other evidence has first been reported, there is a lag time between accepting changes in procedures, treatments and tests in medical care at centers where such research is carried out or reviewed, and establishing them as routine practice generally in clinical care.

Evidence-based medicine seeks to promote practices that has been shown, through the scientific method to have validity by empiric proof. As such, it currently encompasses only a very small minority of actual practices in clinical medicine and surgery. More often, recommendations are made on the basis of best evidence that are reasonable, but not proven. Evidence-based medicine is also a philosophy, however, that seeks to validate practices by finding proof.

Steps in evidence-based medicine

1. "Ask" - Formulate a well-structured clinical questions
2. "Acquire". Systematically search for an answer.
3. "Appraise". Appraise the quality of the answer found.
4. "Apply". Apply the answers to a patient.
5. "Assess". Evaluate one's performance

Classification

Two types of evidence-based medicine have been proposed.

Evidence-based guidelines

Evidence-based guidelines (EBG) is the practice of evidence-based medicine at the organizational or institutional level. This includes the production of guidelines, policy, and regulations.

Evidence-based individual decision making

Evidence-based individual decision (EBID) making is evidence-based medicine as practiced by the individual health care provider and an individual patient. There is concern that current evidence-based medicine focuses excessively on EBID.

Evidence-based individual decision making can be further divided into three modes, "doer", "user", "replicator" by the intensity of the work by the individual. This categorization somewhat parallels the theory of Diffusion of innovations, but without pejorative terms, in which adopters of innovation are categorized as innovators, early adopters, early majority, late majority and laggards. This categorization for doctors is supported by a preliminary empirical study of Green et al that grouped doctors into Seekers, Receptives, Traditionalists, and Pragmatists. The study of Green et al has not been externally validated.

Doer

The "doer" of evidence-based medicine does at least the first four steps (above) of evidence-based medicine are performed

If the Doers are the same as the "Seekers" in the study of Green, then this group may be 3% of physicians.

User

For the "user" of evidence-based medicine, "[literature] searches are restricted to evidence sources that have already undergone critical appraisal by others, such as evidence-based guidelines or evidence summaries". More recently, the 5S search strategy, which starts with the search of "summaries" (evidence-based textbooks) is a more practical approach.

If the Users are the same as the "Receptives" in the study of Green, then this group may be 57% of physicians.

Replicator

For the "replicator", "decisions of respected opinion leaders are followed"

If the Replicators are the same as the "Traditionalists" and "Pragmatists" combined in the study of Green, then this group may be 40% of physicians.

Metrics used in evidence-based medicine

Diagnosis

• Sensitivity and specificity
• Likelihood ratios

Interventions

Relative measures

• Relative risk ratio
• Relative risk reduction

Absolute measures

• Absolute risk reduction
• Number needed to treat
• Number needed to screen
• Number needed to harm

Health policy

• Cost per year of life saved
• Years (or months or days) of life saved. "A gain in life expectancy of a month from a preventive intervention targeted at populations at average risk and a gain of a year from a preventive intervention targeted at populations at elevated risk can both be considered large."

Experimental trials: producing the evidence

Randomized controlled clinical trials

"A clinical trial is defined as a prospective scientific experiment that involves human subjects in whom treatment is initiated for the evaluation of a therapeutic intervention. In a randomized controlled clinical trial, each patient is assigned to receive a specific treatment intervention by a chance mechanism."(Stanley K. Design of randomized controlled trials. Circulation. 115(9):1164-9, 2007 Mar 6. UI: 17339574) The theory behind these trials is that the value of a treatment will be shown in an objective way, and, though usually unstated, there is an assumption that the results of the trial will be applicable to the care of patients who have the condition that was treated.

Ethics in randomization

Is it ethical to treat patients according to a randomization schedule? The answer is:sometimes, depending on the choice of treatments, the medical condition of the patient, and whether the patient has a choice in the matter. Take a university professor who has just received the devastating diagnosis of a malignant brain tumor. Let us say that this particular tumor is resistant to radiation treatment and has infiltrated too much of the brain to be surgically removed, the professor has a fatal disease. There is one drug (Drug A) that has shown a limited benefit in clinical practice to retarding the growth of this tumor, but there not only no known cure for the professor's condition, there is not even a truly effective treatment to slow the progression of the disease. There is a thoeretical reason to believe that Drug B may be curative-or at least helpful, and Drug B has been tested in animal studies that indicate it should be reasonably safe in humans. In this situation, asking the professor to participate in a trial of Drug A, versus Drug B, in which the choice will be according to a code generated by a computer program is not unethical, assuming that the professor understands and agrees. However, let's change the scenerio. If there is a treatment that has some benefit, is it ethical then to ask for the professor's participation in this study? Let's go further, perhaps there is a treatment that has been reported to cure 10% of patients?

In most randomized trials, there is

Evidence synthesis: summarizing the evidence

Systematic review

Meta-analysis

Systematic reviews that quantitatively pool results from research studies are called meta-analyses.

Incorporating evidence into clinical care

Practicing clinicians usually cite the lack of time for reading newer textbooks or journals. However, the emergence of new types of evidence can change the way doctors treat patients. Unfortuantely the recent scientific evidence gathered through well controlled clinical trials usually do not reach the busy clinicians in real time. Another potential problem lies in the fact that there may be numerous trials on similar interventions and outcomes but they are not systematically reviewed or meta-analyzed.

Medical informatics

An essential adjunct to the practice of evidence-based medicine (EBM) is medical informatics (MI) which focuses on creating tools to access and apply the best evidence for making decisions about patient care [Sackett et al, 2000].

Before practicing EBM, informaticians (or informationists) must be familiar with medical journals, literature databases, medical textbooks, practice guidelines, and the growing number of other dedicated evidence-based resources, like the Cochrane Database of Systematic Reviews and Clinical Evidence [Mendelson and Carino 2005].

Similarly, for practicing medical informatics properly, it is essential to have an understanding of EBM, including the ability to phrase an answerable question, locate and retrieve the best evidence, and critically appraise and apply it [Hersh 2002, Shearer et al., 2001].

Studies of the effectiveness of teaching evidence-based medicine

A systematic review of the effectiveness of teaching concluded "standalone teaching improved knowledge but not skills, attitudes, or behaviour. Clinically integrated teaching improved knowledge, skills, attitudes, and behaviour."

Two systematic reviews of provide the framework below for measuring outcomes.

Information retrieval

Increasing use of information

A randomized controlled trial of volunteer senior medical students found that access to information portal on a handheld computer increased self-reported use of information. The information portal contained multiple pre-appraised resources, including a textbook and drug resource, and would best resemble the "user" mode. The study was not able to isolate with resources in the portal had increased use. It is possible that the benefit was solely due to the textbook or drug resource.

A randomized controlled trial of teaching and encouraging use of MEDLINE by medical resident physicians showed increased searching for evidence during 6-8 weeks of observation. Based on the median number of searches and hours spent searching, each search averaged 22 minutes, which may not be sustainable over long term.

Improving clinical care

A controlled trial of teaching the "user" mode (see above) was negative. However, this study encouraged the use of syntheses and synopses and did not encourage the more practical "summaries" (evidence-based textbooks) of the "5S" search strategy.

Information awareness

Increasing use of information

A cluster randomized trial of McMaster Premium LiteratUre Service (PLUS) led to " increased the utilization of evidence-based information from a digital library by practicing physicians."

Improving clinical care

No controlled studies have addressed improving clinical care by use of information awareness strategies.

Clinical reasoning

Improving clinical care

A controlled trial of teaching Bayesian principles (probabilistic reasoning) "improves the efficiency of test ordering."

References

1. Sackett DL, Straus SE, Richardson WS, Rosenberg W, Haynes RB. Evidence-based medicine: how to practice and teach EBM. 2nd ed. New York, NY: Churchhill Livingstone, 2000.
2. Mendelson D, Carino TV, Evidence-Based Medicine In The United States-De Rigueur Or Dream Deferred? Health Affairs, 2005, 24: 133 - 136. doi: 10.1377/hlthaff.24.1.133
3. Hersh W, Medical informatics education: an alternative pathway for training informationists, J Med Libr Assoc, 2002, 90(1): 76 - 79.
4. Shearer BS, Seymour A, Capitani C. Bringing the best of medical librarianship to the patient team, J Med Libr Assoc 2001; 90: 22-31.

See also

• Clinical decision support system
• Marsha Angell

External links

• ACC.org - 'What Is Evidence-Based Medicine?' American College of Cardiology
• AHRQ.gov - 'U.S. Preventive Services Task Force (USPSTF)', Agency for Health Care Research and Quality
• BEEMCourse.com - 'The Best Evidence In Emergency Medicine (BEEM) Team' Group based out of McMaster University (Hamilton, Ontario, Canada) that actively reviews the best emerging evidence based research in emergency medicine.
• BMJ.com - 'Evidence based medicine: what it is and what it isn't: It's about integrating individual clinical expertise and the best external evidence', (editorial) British Medical Journal, vol 312, p 71-72 (January 13, 1996)
• BMJ.com - 'Evidence based medicine: Socratic dissent', (Education and debate) British Medical Journal, vol 310, p 1126-1127 (April 29, 1995)
• CEBM.net - Oxford Centre for Evidence-Based Medicine (UK)
• CMAJ.ca - 'Evidence-based medicine: a commentary on common criticisms', Dr. Sharon E. Straus, Dr. Finlay A. McAlister, Canadian Medical Association Journal, Vol 163, No 7, pp 837 - 841 (October 3, 2000)
• Cochrane.org - 'The Cochrane Collaboration: The reliable source for evidence in healthcare' (systematic reviews of the effects of health care interventions), Cochrane Library
• EBOnCall.org - 'Evidence compendia' (evidence-based summaries of 38 on-call medical conditions), Evidence-Based On-Call (EBOC)
• Evidence-based medicine, What is ? - The What is...? series explains the key concepts in a clear, concise and accessible format.
• GPNoteBook.co.uk - 'Evidence-based medicine (EBM)', General Practice Notebook
• HERTS.ac.uk - Evidence-Based Medicine', University of Hertfordshire
• JournalReview.org - 'An unbiased forum for review of the medical literature', An On-Line journal club
• JR2.ox.ac.uk - 'Bandolier: Evidence-based thinking about health care', Bandolier (journal)
• medlib.bu.edu = 'Introduction to Evidence-Based Medicine' Boston University Medical Center Library
• MJA.com.au - 'Evidence-based medicine: useful tools for decision making', Jonathan C. Craig, Les M. Irwig, Martin R. Stockler, Medical Journal of Australia, vol 174, p 248-253 (2001)
• SHEF.ac.uk - 'Netting the Evidence: A ScHARR Introduction to Evidence Based Practice on the Internet' (resource directory), University of Sheffield
• TRIP Database - 'TRIP Database - EBM search engine' (resource directory), TRIP Knowledge Service
• BMJ.BMJjournals.com - 'Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials', Gordon C S Smith, Jill P Pell, British Medical Journal, Vol 327, pp 1459-1461 (20 December, 2003) (An entertaining study showing that situations still exist where RCTs are unnecessary.)