Evidence-based medicine
Encyclopedia
Evidence-based medicine or evidence-based practice (EBP) aims to apply the best available evidence
gained from the scientific method
to clinical decision making
. It seeks to assess the strength of evidence of the risks and benefits of treatments
(including lack of treatment) and diagnostic tests. Evidence quality can be assessed based on the source type (from meta-analyses and systematic reviews of double-blind
, placebo-controlled clinical trials at the top end, down to conventional wisdom
at the bottom), as well as other factors including statistical validity, clinical relevance, currency, and peer-review acceptance.
EBM/EBP recognizes that many aspects of health care depend on individual factors such as quality-
and value-of-life
judgments, which are only partially subject to scientific methods. EBP, however, seeks to clarify those parts of medical practice that are in principle subject to scientific methods and to apply these methods to ensure the best prediction
of outcomes in medical treatment, even as debate continues about which outcomes are desirable.
Because this approach is used in allied related fields, including dentistry
, nursing
, and psychology
, evidence-based practice is a more encompassing term.
. There is concern that current evidence-based medicine focuses excessively on EBID.
The American Academy of Family Physicians
(AAFP) says that DynaMed may be of assistance to family physicians in answering clinical questions with high-quality evidence.
, engineering
, and statistics
, such as the systematic review of medical literature
, meta-analysis
, risk-benefit analysis
, and randomized controlled trial
s (RCTs), EBM aims for the ideal that healthcare professionals should make "conscientious, explicit, and judicious use of current best evidence" in their everyday practice. Ex cathedra
statements by the "medical expert" are considered to be least valid form of evidence. All "experts" are now expected to reference their pronouncements to scientific studies.
The systematic review
of published research studies is a major method used for evaluating particular treatments. The Cochrane Collaboration
is one of the best-known, respected examples of systematic reviews. Like other collections of systematic reviews, it requires authors to provide a detailed and repeatable plan of their literature search and evaluations of the evidence. Once all the best evidence is assessed, treatment is categoried as "likely to be beneficial", "likely to be harmful", or "evidence did not support either benefit or harm".
A 2007 analysis of 1016 systematic reviews from all 50 Cochrane
Collaboration Review Groups found that 44% of the reviews concluded that the intervention was "likely to be beneficial", 7% concluded that the intervention was "likely to be harmful", and 49% concluded that evidence "did not support either benefit or harm". 96% recommended further research. A 2001 review of 160 Cochrane systematic reviews (excluding complementary treatments) in the 1998 database revealed that, according to two readers, 41.3% concluded positive or possibly positive effect, 20% concluded evidence of no effect, 8.1% concluded net harmful effects, and 21.3% of the reviews concluded insufficient evidence. A review of 145 alternative medicine
Cochrane reviews using the 2004 database revealed that 38.4% concluded positive effect or possibly positive (12.4%) effect, 4.8% concluded no effect, 0.69% concluded harmful effect, and 56.6% concluded insufficient evidence.
Generally, there are three distinct, but interdependent, areas of EBM. The first is to treat individual patients with acute or chronic pathologies by treatments supported in the most scientifically valid medical literature. Thus, medical practitioners would select treatment options for specific cases based on the best research for each patient they treat. The second area is the systematic review
of medical literature to evaluate the best studies on specific topics. This process can be very human-centered, as in a journal club
, or highly technical, using computer programs and information techniques such as data mining
. Increased use of information technology
turns large volumes of information into practical guides. Finally, evidence-based medicine can be understood as a medical "movement" in which advocates work to popularize the method and usefulness of the practice in the public, patient communities, educational institutions, and continuing education
of practicing professionals .
with allocation concealment and complete follow-up involving a homogeneous patient population and medical condition. In contrast, patient testimonials, case reports, and even expert opinion have little value as proof because of the placebo effect, the biases inherent in observation and reporting of cases, difficulties in ascertaining who is an expert, and more.
uses a similar system with categories labeled A, B, C, and D. The above Levels are only appropriate for treatment or interventions; different types of research are required for assessing diagnostic accuracy or natural history and prognosis, and hence different "levels" are required. For example, the Oxford Centre for Evidence-based Medicine suggests levels of evidence (LOE) according to the study designs and critical appraisal of prevention, diagnosis, prognosis, therapy, and harm studies:
"Extrapolations" are where data is used in a situation which has potentially clinically important differences than the original study situation. Thus, the quality of evidence to support a clinical decision is a combination of the quality of research data and the clinical 'directness' of the data.
Despite the differences between systems, the purposes are the same: to guide users of clinical research information about which studies are likely to be most valid. However, the individual studies still require careful critical appraisal.
Note: The all or none principle is met when all patients died before the Rx became available, but some now survive on it; or when some patients died before the Rx became available, but none now die on it.
. The differences in likelihood ratio between clinical tests can be used to prioritize clinical tests according to their usefulness in a given clinical situation.
curve (AUC-ROC) reflects the relationship between sensitivity and specificity
for a given test. High-quality tests will have an AUC-ROC approaching 1, and high-quality publications about clinical tests will provide information about the AUC-ROC. Cutoff values for positive and negative tests can influence specificity and sensitivity, but they do not affect AUC-ROC.
or Number needed to harm
are ways of expressing the effectiveness and safety of an intervention in a way that is clinically meaningful. In general, NNT is always computed with respect to two treatments A and B, with A typically a drug and B a placebo (in our example above, A is a 5-year treatment with the hypothetical drug, and B is no treatment). A defined endpoint has to be specified (in our example: the appearance of colon cancer in the 5 year period). If the probabilities pA and pB of this endpoint under treatments A and B, respectively, are known, then the NNT is computed as 1/(pB-pA). The NNT for breast mammography is 285; that is, 285 mammograms need to be performed to diagnose one breast cancer. As another example, an NNT of 4 means if 4 patients are treated, only one would respond.
An NNT of 1 is the most effective and means each patient treated responds, e.g., in comparing antibiotics with placebo in the eradication of Helicobacter pylori
. An NNT of 2 or 3 indicates that a treatment is quite effective (with one patient in 2 or 3 responding to the treatment). An NNT of 20 to 40 can still be considered clinically effective.
" for clinical practice there are a number of limitations and criticisms of its use.
do not remove the problem of extrapolation to different populations or longer timeframes. Even if several top-quality studies are available, questions always remain about how far, and to which populations, their results are "generalizable". Furthermore, skepticism about results may always be extended to areas not explicitly covered: for example, a drug may influence a "secondary endpoint" such as test result (blood pressure, glucose, or cholesterol levels) without having the power to show that it decreases overall mortality or morbidity in a population.
The quality of studies performed varies, making it difficult to compare them and generalize about the results.
Certain groups have been historically under-researched (racial minorities and people with many co-morbid diseases), and thus the literature is sparse in areas that do not allow for generalizing.
and retrieval bias is required.
Failure to publish negative trials is the most obvious gap. Clinical Trials Registers have been established in a number of countries, and the Declaration of Helsinki 2008 (Principle 19) requires that "every clinical trial must be registered in a publicly accessible database before recruitment of the first subject". Changes in publication methods, particularly related to the Web, should reduce the difficulty of obtaining publication for a paper on a trial that concludes it did not prove anything new, including its starting hypothesis.
Treatment effectiveness reported from clinical studies may be higher than that achieved in later routine clinical practice due to the closer patient monitoring during trials that leads to much higher compliance rates.
The studies that are published in medical journals may not be representative of all the studies that are completed on a given topic (published and unpublished) or may be unreliable due to conflicts of interest. Thus the array of evidence available on particular therapies may not be well-represented in the literature. A 2004 statement by the International Committee of Medical Journal Editors (that they will refuse to publish clinical trial results if the trial was not recorded publicly at its outset) may help with this, although this has not yet been implemented.
David Sackett
writes that "the practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research".
is being suspended from most of the top-ranked medical literature
. Thus data of rare medical
situations, in which large randomized double-blind placebo-controlled trials cannot be conducted, may be rejected from publication and be restricted from the medical community.
proponents), we must focus more on a claim's prior plausibility rather than prioritizing just the volume of evidence. To differentiate this approach from the approach normally taken when evaluating plausible scientific claims some have labelled this science based medicine. It could be argued that proper use of the evidence based medicine model should produce the same conclusions.
Science based medicine is based upon the idea that we can make logical and rational judgements about what is likely to be true based on what is already well established scientific “fact”. This does not imply that new or radical ideas are implicitly thrown out, just that the standard of evidence must be increasingly high the more extraordinary the claims.
, have been criticized as incompletely justified by evidence. In many cases, it is unknown whether a particular "disease" has one, several, or no underlying biological causes (with controversy arising over whether some diseases are merely an artifact of the attempt to construct a unified classification scheme, rather than a "real" disease).
While some experts point to statistics in support of the idea that a lack of adoption of research findings results in suboptimal treatment for many patients, others emphasize the importance of the skill of the practitioner and the customization of the treatment to fit individual needs. There is some controversy over whether mental illnesses is too complex for broad population studies to be helpful.
, Although testing medical interventions for efficacy
has existed since the time of Avicenna
's The Canon of Medicine
in the 11th century, it was only in the 20th century that this effort evolved to impact almost all fields of health care and policy. Professor Archie Cochrane
, a Scottish
epidemiologist, through his book Effectiveness and Efficiency: Random Reflections on Health Services (1972) and subsequent advocacy, caused increasing acceptance of the concepts behind evidence-based practice.
Cochrane's work was honoured through the naming of centres of evidence-based medical research — Cochrane Centres — and an international organization, the Cochrane Collaboration
. The explicit methodologies used to determine "best evidence" were largely established by the McMaster University
research group led by David Sackett
and Gordon Guyatt
. Guyatt later coined the term “evidence-based” in 1990. The term "evidence-based medicine" first appeared in the medical literature in 1992 in a paper by Guyatt et al. Relevant journals include the British Medical Journal's Clinical Evidence, the Journal Of Evidence-Based Healthcare and Evidence Based Health Policy. All of these were co-founded by Anna Donald
, an Australian pioneer in the discipline.
Some people are willing to take their chances to gamble their health on the success of new drugs or old drugs in new situations which may not yet have been fully tested in clinical trials. However insurance companies are reluctant to take on the job of funding such treatments, preferring instead to take the safer route of awaiting the results of clinical testing and leaving the funding of such trials to the manufacturer seeking a license.
Sometimes caution errs in the other direction. Kaiser Permanente
did not change its methods of evaluating whether or not new therapies were too "experimental" to be covered until it was successfully sued twice: once for delaying in vitro fertilization treatments for two years after the courts determined that scientific evidence of efficacy and safety had reached the "reasonable" stage; and in another case where Kaiser refused to pay for liver transplantation in infants when it had already been shown to be effective in adults, on the basis that use in infants was still "experimental." Here again, the problem of induction plays a key role in arguments.
General:
Evidence
Evidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either presumed to be true, or were themselves proven via evidence, to demonstrate an assertion's truth...
gained from the scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of...
to clinical decision making
Decision making
Decision making can be regarded as the mental processes resulting in the selection of a course of action among several alternative scenarios. Every decision making process produces a final choice. The output can be an action or an opinion of choice.- Overview :Human performance in decision terms...
. It seeks to assess the strength of evidence of the risks and benefits of treatments
Therapy
This is a list of types of therapy .* Adventure therapy* Animal-assisted therapy* Aquatic therapy* Aromatherapy* Art and dementia* Art therapy* Authentic Movement* Behavioral therapy* Bibliotherapy* Buteyko Method* Chemotherapy...
(including lack of treatment) and diagnostic tests. Evidence quality can be assessed based on the source type (from meta-analyses and systematic reviews of double-blind
Double-blind
A blind or blinded experiment is a scientific experiment where some of the people involved are prevented from knowing certain information that might lead to conscious or subconscious bias on their part, invalidating the results....
, placebo-controlled clinical trials at the top end, down to conventional wisdom
Conventional wisdom
Conventional wisdom is a term used to describe ideas or explanations that are generally accepted as true by the public or by experts in a field. Such ideas or explanations, though widely held, are unexamined. Unqualified societal discourse preserves the status quo. It codifies existing social...
at the bottom), as well as other factors including statistical validity, clinical relevance, currency, and peer-review acceptance.
EBM/EBP recognizes that many aspects of health care depend on individual factors such as quality-
Quality of life
The term quality of life is used to evaluate the general well-being of individuals and societies. The term is used in a wide range of contexts, including the fields of international development, healthcare, and politics. Quality of life should not be confused with the concept of standard of...
and value-of-life
Value of life
The potency of life is an economic value assigned to life in general, or to specific living organisms. In social and political sciences, it is the marginal cost of death prevention in a certain class of circumstances. As such, it is a statistical term, the cost of reducing the number of deaths by...
judgments, which are only partially subject to scientific methods. EBP, however, seeks to clarify those parts of medical practice that are in principle subject to scientific methods and to apply these methods to ensure the best prediction
Prediction
A prediction or forecast is a statement about the way things will happen in the future, often but not always based on experience or knowledge...
of outcomes in medical treatment, even as debate continues about which outcomes are desirable.
Because this approach is used in allied related fields, including dentistry
Dentistry
Dentistry is the branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the oral cavity, maxillofacial area and the adjacent and associated structures and their impact on the human body. Dentistry is widely considered...
, nursing
Nursing
Nursing is a healthcare profession focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life from conception to death....
, and psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
, evidence-based practice is a more encompassing term.
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. This approach has also been called evidence based healthcare.Evidence-based individual decision making
Evidence-based individual decision (EBID) making is evidence-based medicine as practiced by the individual health care providerHealth care provider
A health care provider is an individual or an institution that provides preventive, curative, promotional or rehabilitative health care services in a systematic way to individuals, families or communities....
. There is concern that current evidence-based medicine focuses excessively on EBID.
The American Academy of Family Physicians
American Academy of Family Physicians
The American Academy of Family Physicians was founded in 1947 to promote the science and art of family medicine. It is one of the largest medical organizations in the United States, with over 100,000 members...
(AAFP) says that DynaMed may be of assistance to family physicians in answering clinical questions with high-quality evidence.
Process and progress
Using techniques from scienceScience
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
, engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
, and statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
, such as the systematic review of medical literature
Medical literature
Medical literature refers to articles in journals and texts in books devoted to the field of medicine.Contemporary and historic views regarding diagnosis, prognosis and treatment of medical conditions have been documented for thousands of years. The Edwin Smith papyrus is the first known medical...
, meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
, risk-benefit analysis
Risk-benefit analysis
Risk–benefit analysis is the comparison of the risk of a situation to its related benefits. Exposure to personal risk is recognized as a normal aspect of everyday life. We accept a certain level of risk in our lives as necessary to achieve certain benefits. In most of these risks we feel as though...
, and randomized controlled trial
Randomized controlled trial
A randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
s (RCTs), EBM aims for the ideal that healthcare professionals should make "conscientious, explicit, and judicious use of current best evidence" in their everyday practice. Ex cathedra
Ex Cathedra
Ex Cathedra is a British choir and early music ensemble based in Birmingham in the West Midlands, England. It performs choral music spanning the 15th to 21st centuries, and regularly commissions new works....
statements by the "medical expert" are considered to be least valid form of evidence. All "experts" are now expected to reference their pronouncements to scientific studies.
The systematic review
Systematic review
A systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
of published research studies is a major method used for evaluating particular treatments. The Cochrane Collaboration
Cochrane Collaboration
The Cochrane Collaboration is a group of over 28,000 volunteers in more than 100 countries who review the effects of health care interventions tested in biomedical randomized controlled trials. A few more recent reviews have also studied the results of non-randomized, observational studies...
is one of the best-known, respected examples of systematic reviews. Like other collections of systematic reviews, it requires authors to provide a detailed and repeatable plan of their literature search and evaluations of the evidence. Once all the best evidence is assessed, treatment is categoried as "likely to be beneficial", "likely to be harmful", or "evidence did not support either benefit or harm".
A 2007 analysis of 1016 systematic reviews from all 50 Cochrane
Archie Cochrane
Archibald Leman Cochrane was a Scottish doctor whose name is synonymous with scientific method in medicine.-Biography:Cochrane was born in Kirklands, Galashiels, Scotland...
Collaboration Review Groups found that 44% of the reviews concluded that the intervention was "likely to be beneficial", 7% concluded that the intervention was "likely to be harmful", and 49% concluded that evidence "did not support either benefit or harm". 96% recommended further research. A 2001 review of 160 Cochrane systematic reviews (excluding complementary treatments) in the 1998 database revealed that, according to two readers, 41.3% concluded positive or possibly positive effect, 20% concluded evidence of no effect, 8.1% concluded net harmful effects, and 21.3% of the reviews concluded insufficient evidence. A review of 145 alternative medicine
Alternative medicine
Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....
Cochrane reviews using the 2004 database revealed that 38.4% concluded positive effect or possibly positive (12.4%) effect, 4.8% concluded no effect, 0.69% concluded harmful effect, and 56.6% concluded insufficient evidence.
Generally, there are three distinct, but interdependent, areas of EBM. The first is to treat individual patients with acute or chronic pathologies by treatments supported in the most scientifically valid medical literature. Thus, medical practitioners would select treatment options for specific cases based on the best research for each patient they treat. The second area is the systematic review
Systematic review
A systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
of medical literature to evaluate the best studies on specific topics. This process can be very human-centered, as in a journal club
Journal club
A journal club is a group of individuals who meet regularly to critically evaluate recent articles in scientific literature. Journal clubs are usually organized around a defined subject in basic or applied research. For example, the application of evidence-based medicine to some area of medical...
, or highly technical, using computer programs and information techniques such as data mining
Data mining
Data mining , a relatively young and interdisciplinary field of computer science is the process of discovering new patterns from large data sets involving methods at the intersection of artificial intelligence, machine learning, statistics and database systems...
. Increased use of information technology
Information technology
Information technology is the acquisition, processing, storage and dissemination of vocal, pictorial, textual and numerical information by a microelectronics-based combination of computing and telecommunications...
turns large volumes of information into practical guides. Finally, evidence-based medicine can be understood as a medical "movement" in which advocates work to popularize the method and usefulness of the practice in the public, patient communities, educational institutions, and continuing education
Continuing education
Continuing education is an all-encompassing term within a broad spectrum of post-secondary learning activities and programs. The term is used mainly in the United States and Canada...
of practicing professionals .
Ranking the quality of evidence
Evidence-based medicine categorizes different types of clinical evidence and rates or grades them http://www.essentialevidenceplus.com/product/ebm_loe.cfm?show=grade according to the strength of their freedom from the various biases that beset medical research. For example, the strongest evidence for therapeutic interventions is provided by systematic review of randomized, triple-blind, placebo-controlled trialsPlacebo-controlled studies
A Placebo-controlled study is a way of testing a medical therapy in which, in addition to a group of subjects that receives the treatment to be evaluated, a separate control group receives a sham "placebo" treatment which is specifically designed to have no real effect...
with allocation concealment and complete follow-up involving a homogeneous patient population and medical condition. In contrast, patient testimonials, case reports, and even expert opinion have little value as proof because of the placebo effect, the biases inherent in observation and reporting of cases, difficulties in ascertaining who is an expert, and more.
US Preventive Services Task Force
Systems to stratify evidence by quality have been developed, such as this one by the U.S. Preventive Services Task Force for ranking evidence about the effectiveness of treatments or screening:- Level I: Evidence obtained from at least one properly designed randomized controlled trialRandomized controlled trialA randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
. - Level II-1: Evidence obtained from well-designed controlled trials without randomizationRandomizationRandomization is the process of making something random; this means:* Generating a random permutation of a sequence .* Selecting a random sample of a population ....
. - Level II-2: Evidence obtained from well-designed cohortCohort studyA cohort study or panel study is a form of longitudinal study used in medicine, social science, actuarial science, and ecology. It is an analysis of risk factors and follows a group of people who do not have the disease, and uses correlations to determine the absolute risk of subject contraction...
or case-controlCase-controlA case-control study is a type of study design in epidemiology. Case-control studies are used to identify factors that may contribute to a medical condition by comparing subjects who have that condition with patients who do not have the condition but are otherwise similar .Case-control studies are...
analytic studies, preferably from more than one center or research group. - Level II-3: Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled trials might also be regarded as this type of evidence.
- Level III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
National Health Service
The UK National Health ServiceNational Health Service
The National Health Service is the shared name of three of the four publicly funded healthcare systems in the United Kingdom. They provide a comprehensive range of health services, the vast majority of which are free at the point of use to residents of the United Kingdom...
uses a similar system with categories labeled A, B, C, and D. The above Levels are only appropriate for treatment or interventions; different types of research are required for assessing diagnostic accuracy or natural history and prognosis, and hence different "levels" are required. For example, the Oxford Centre for Evidence-based Medicine suggests levels of evidence (LOE) according to the study designs and critical appraisal of prevention, diagnosis, prognosis, therapy, and harm studies:
- Level A: Consistent Randomised Controlled Clinical TrialRandomized controlled trialA randomized controlled trial is a type of scientific experiment - a form of clinical trial - most commonly used in testing the safety and efficacy or effectiveness of healthcare services or health technologies A randomized controlled trial (RCT) is a type of scientific experiment - a form of...
, cohort studyCohort studyA cohort study or panel study is a form of longitudinal study used in medicine, social science, actuarial science, and ecology. It is an analysis of risk factors and follows a group of people who do not have the disease, and uses correlations to determine the absolute risk of subject contraction...
, all or none (see note below), clinical decision rule validated in different populations. - Level B: Consistent Retrospective Cohort, Exploratory Cohort, Ecological Study, Outcomes Research, case-control study; or extrapolations from level A studies.
- Level C: Case-series study or extrapolations from level B studies.
- Level D: Expert opinion without explicit critical appraisal, or based on physiologyPhysiologyPhysiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
, bench research or first principles.
GRADE Working Group
A newer system is by the GRADE Working Group and takes in account more dimensions than just the quality of medical evidence."Extrapolations" are where data is used in a situation which has potentially clinically important differences than the original study situation. Thus, the quality of evidence to support a clinical decision is a combination of the quality of research data and the clinical 'directness' of the data.
Despite the differences between systems, the purposes are the same: to guide users of clinical research information about which studies are likely to be most valid. However, the individual studies still require careful critical appraisal.
Note: The all or none principle is met when all patients died before the Rx became available, but some now survive on it; or when some patients died before the Rx became available, but none now die on it.
Categories of recommendations
In guidelines and other publications, recommendation for a clinical service is classified by the balance of risk versus benefit of the service and the level of evidence on which this information is based. The U.S. Preventive Services Task Force uses:- Level A: Good scientific evidence suggests that the benefits of the clinical service substantially outweigh the potential risks. Clinicians should discuss the service with eligible patients.
- Level B: At least fair scientific evidence suggests that the benefits of the clinical service outweighs the potential risks. Clinicians should discuss the service with eligible patients.
- Level C: At least fair scientific evidence suggests that there are benefits provided by the clinical service, but the balance between benefits and risks are too close for making general recommendations. Clinicians need not offer it unless there are individual considerations.
- Level D: At least fair scientific evidence suggests that the risks of the clinical service outweighs potential benefits. Clinicians should not routinely offer the service to asymptomatic patients.
- Level I: Scientific evidence is lacking, of poor quality, or conflicting, such that the risk versus benefit balance cannot be assessed. Clinicians should help patients understand the uncertainty surrounding the clinical service.
Statistical measures
Evidence-based medicine attempts to express clinical benefits of tests and treatments using mathematical methods. Tools used by practitioners of evidence-based medicine include:Likelihood ratio
The pre-test odds of a particular diagnosis, multiplied by the likelihood ratio, determines the post-test odds. (Odds can be calculated from, and then converted to, the [more familiar] probability.) This reflects Bayes' theoremBayes' theorem
In probability theory and applications, Bayes' theorem relates the conditional probabilities P and P. It is commonly used in science and engineering. The theorem is named for Thomas Bayes ....
. The differences in likelihood ratio between clinical tests can be used to prioritize clinical tests according to their usefulness in a given clinical situation.
AUC-ROC
The area under the receiver operating characteristicReceiver operating characteristic
In signal detection theory, a receiver operating characteristic , or simply ROC curve, is a graphical plot of the sensitivity, or true positive rate, vs. false positive rate , for a binary classifier system as its discrimination threshold is varied...
curve (AUC-ROC) reflects the relationship between sensitivity and specificity
Sensitivity and specificity
Sensitivity and specificity are statistical measures of the performance of a binary classification test, also known in statistics as classification function. Sensitivity measures the proportion of actual positives which are correctly identified as such Sensitivity and specificity are statistical...
for a given test. High-quality tests will have an AUC-ROC approaching 1, and high-quality publications about clinical tests will provide information about the AUC-ROC. Cutoff values for positive and negative tests can influence specificity and sensitivity, but they do not affect AUC-ROC.
Number needed to treat / harm
Number needed to treatNumber needed to treat
The number needed to treat is an epidemiological measure used in assessing the effectiveness of a health-care intervention, typically a treatment with medication. The NNT is the average number of patients who need to be treated to prevent one additional bad outcome...
or Number needed to harm
Number needed to harm
The number needed to harm is an epidemiological measure that indicates how many patients need to be exposed to a risk-factor over a specific period to cause harm in one patient that would not otherwise have been harmed. It is defined as the inverse of the attributable risk...
are ways of expressing the effectiveness and safety of an intervention in a way that is clinically meaningful. In general, NNT is always computed with respect to two treatments A and B, with A typically a drug and B a placebo (in our example above, A is a 5-year treatment with the hypothetical drug, and B is no treatment). A defined endpoint has to be specified (in our example: the appearance of colon cancer in the 5 year period). If the probabilities pA and pB of this endpoint under treatments A and B, respectively, are known, then the NNT is computed as 1/(pB-pA). The NNT for breast mammography is 285; that is, 285 mammograms need to be performed to diagnose one breast cancer. As another example, an NNT of 4 means if 4 patients are treated, only one would respond.
An NNT of 1 is the most effective and means each patient treated responds, e.g., in comparing antibiotics with placebo in the eradication of Helicobacter pylori
Helicobacter pylori
Helicobacter pylori , previously named Campylobacter pyloridis, is a Gram-negative, microaerophilic bacterium found in the stomach. It was identified in 1982 by Barry Marshall and Robin Warren, who found that it was present in patients with chronic gastritis and gastric ulcers, conditions that were...
. An NNT of 2 or 3 indicates that a treatment is quite effective (with one patient in 2 or 3 responding to the treatment). An NNT of 20 to 40 can still be considered clinically effective.
Quality of clinical trials
Evidence-based medicine attempts to objectively evaluate the quality of clinical research by critically assessing techniques reported by researchers in their publications.- Trial design considerations. High-quality studies have clearly defined eligibility criteria, and have minimal missing data.
- Generalizability considerations. Studies may only be applicable to narrowly defined patient populations, and may not be generalizable to other clinical contexts.
- Followup. Sufficient time for defined outcomes to occur can influence the study outcomes and the statistical powerStatistical powerThe power of a statistical test is the probability that the test will reject the null hypothesis when the null hypothesis is actually false . The power is in general a function of the possible distributions, often determined by a parameter, under the alternative hypothesis...
of a study to detect differences between a treatment and control arm. - Power. A mathematical calculation can determine if the number of patients is sufficient to detect a difference between treatment arms. A negative study may reflect a lack of benefit, or simply a lack of sufficient quantities of patients to detect a difference.
Limitations
Although evidence-based medicine is becoming regarded as the "gold standardGold standard (test)
In medicine and statistics, gold standard test refers to a diagnostic test or benchmark that is the best available under reasonable conditions. It does not have to be necessarily the best possible test for the condition in absolute terms...
" for clinical practice there are a number of limitations and criticisms of its use.
Ethics
In some cases, such as in open-heart surgery, conducting randomized, placebo-controlled trials is commonly considered to be unethical, although observational studies may address these problems to some degree.Cost
The types of trials considered "gold standard" (i.e. large randomized double-blind placebo-controlled trials) are expensive, so that funding sources play a role in what gets investigated. For example, public authorities may tend to fund preventive medicine studies to improve public health, while pharmaceutical companies fund studies intended to demonstrate the efficacy and safety of particular drugs.Time
The conduction of a randomized controlled trial takes several years until being published, thus data is restricted from the medical community for long years and may be of less relevance at time of publication.Generalizability
Furthermore, evidence-based guidelinesGuideline (medical)
A medical guideline is a document with the aim of guiding decisions and criteria regarding diagnosis, management, and treatment in specific areas of healthcare...
do not remove the problem of extrapolation to different populations or longer timeframes. Even if several top-quality studies are available, questions always remain about how far, and to which populations, their results are "generalizable". Furthermore, skepticism about results may always be extended to areas not explicitly covered: for example, a drug may influence a "secondary endpoint" such as test result (blood pressure, glucose, or cholesterol levels) without having the power to show that it decreases overall mortality or morbidity in a population.
The quality of studies performed varies, making it difficult to compare them and generalize about the results.
Certain groups have been historically under-researched (racial minorities and people with many co-morbid diseases), and thus the literature is sparse in areas that do not allow for generalizing.
Publication bias
It is recognised that not all evidence is made accessible, that this can limit the effectiveness of any approach, and that efforts to reduce publication biasPublication bias
Publication bias is the tendency of researchers, editors, and pharmaceutical companies to handle the reporting of experimental results that are positive differently from results that are negative or inconclusive, leading to bias in the overall published literature...
and retrieval bias is required.
Failure to publish negative trials is the most obvious gap. Clinical Trials Registers have been established in a number of countries, and the Declaration of Helsinki 2008 (Principle 19) requires that "every clinical trial must be registered in a publicly accessible database before recruitment of the first subject". Changes in publication methods, particularly related to the Web, should reduce the difficulty of obtaining publication for a paper on a trial that concludes it did not prove anything new, including its starting hypothesis.
Treatment effectiveness reported from clinical studies may be higher than that achieved in later routine clinical practice due to the closer patient monitoring during trials that leads to much higher compliance rates.
The studies that are published in medical journals may not be representative of all the studies that are completed on a given topic (published and unpublished) or may be unreliable due to conflicts of interest. Thus the array of evidence available on particular therapies may not be well-represented in the literature. A 2004 statement by the International Committee of Medical Journal Editors (that they will refuse to publish clinical trial results if the trial was not recorded publicly at its outset) may help with this, although this has not yet been implemented.
Populations, clinical experience, and dubious diagnoses
EBM applies to groups of people but this does not preclude clinicians from using their personal experience in deciding how to treat the person in front of them. In The limits of evidence-based medicine, Tonelli advises that "the knowledge gained from clinical research does not directly answer the primary clinical question of what is best for the patient at hand." and suggests that evidence-based medicine should not discount the value of clinical experience.David Sackett
David Sackett
David Lawrence Sackett, OC, FRSC is a Canadian medical doctor and a pioneer in evidence-based medicine. He founded the first department of clinical epidemiology in Canada at McMaster University, and the Oxford Centre for Evidence-Based Medicine...
writes that "the practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research".
Illegitimacy of other types of medical reports
Although has some usefulness in clinical practice, the case reportCase report
In medicine, a case report is a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient. Case reports may contain a demographic profile of the patient, but usually describe an unusual or novel occurrence....
is being suspended from most of the top-ranked medical literature
Medical literature
Medical literature refers to articles in journals and texts in books devoted to the field of medicine.Contemporary and historic views regarding diagnosis, prognosis and treatment of medical conditions have been documented for thousands of years. The Edwin Smith papyrus is the first known medical...
. Thus data of rare medical
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
situations, in which large randomized double-blind placebo-controlled trials cannot be conducted, may be rejected from publication and be restricted from the medical community.
Political criticism
There is a good deal of criticism of evidence based medicine, which is suspected of being — as against what the phrase suggests — in essence a tool not so much for medical science as for health managers, who want to introduce managerialist techniques into medical administration. Thus Dr Michael Fitzpatrick writes: "To some of its critics, in its disparagement of theory and its crude number-crunching, EBM marks a return to 'empiricist quackery' in medical practice . Its main appeal, as Singh and Ernst suggest, is to health economists, policymakers and managers, to whom it appears useful for measuring performance and rationing resources."Science Based Medicine
Some have suggested that when examining implausible claims (such as those made by some alternative medicineAlternative medicine
Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....
proponents), we must focus more on a claim's prior plausibility rather than prioritizing just the volume of evidence. To differentiate this approach from the approach normally taken when evaluating plausible scientific claims some have labelled this science based medicine. It could be argued that proper use of the evidence based medicine model should produce the same conclusions.
Science based medicine is based upon the idea that we can make logical and rational judgements about what is likely to be true based on what is already well established scientific “fact”. This does not imply that new or radical ideas are implicitly thrown out, just that the standard of evidence must be increasingly high the more extraordinary the claims.
In psychiatry
Standard knowledge about mental illnesses, such as the Diagnostic and Statistical Manual of Mental DisordersDiagnostic and Statistical Manual of Mental Disorders
The Diagnostic and Statistical Manual of Mental Disorders is published by the American Psychiatric Association and provides a common language and standard criteria for the classification of mental disorders...
, have been criticized as incompletely justified by evidence. In many cases, it is unknown whether a particular "disease" has one, several, or no underlying biological causes (with controversy arising over whether some diseases are merely an artifact of the attempt to construct a unified classification scheme, rather than a "real" disease).
While some experts point to statistics in support of the idea that a lack of adoption of research findings results in suboptimal treatment for many patients, others emphasize the importance of the skill of the practitioner and the customization of the treatment to fit individual needs. There is some controversy over whether mental illnesses is too complex for broad population studies to be helpful.
History
Traces of evidence-based medicine's origin can be found in ancient GreeceAncient Greece
Ancient Greece is a civilization belonging to a period of Greek history that lasted from the Archaic period of the 8th to 6th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Included in Ancient Greece is the...
, Although testing medical interventions for efficacy
Efficacy
Efficacy is the capacity to produce an effect. It has different specific meanings in different fields. In medicine, it is the ability of an intervention or drug to reproduce a desired effect in expert hands and under ideal circumstances.- Healthcare :...
has existed since the time of Avicenna
Avicenna
Abū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...
's The Canon of Medicine
The Canon of Medicine
The Canon of Medicine is an encyclopedia of Galenic medicine in five books compiled by Ibn Sīnā and completed in 1025. It presents a clear and organized summary of all the medical knowledge of the time...
in the 11th century, it was only in the 20th century that this effort evolved to impact almost all fields of health care and policy. Professor Archie Cochrane
Archie Cochrane
Archibald Leman Cochrane was a Scottish doctor whose name is synonymous with scientific method in medicine.-Biography:Cochrane was born in Kirklands, Galashiels, Scotland...
, a Scottish
Scottish people
The Scottish people , or Scots, are a nation and ethnic group native to Scotland. Historically they emerged from an amalgamation of the Picts and Gaels, incorporating neighbouring Britons to the south as well as invading Germanic peoples such as the Anglo-Saxons and the Norse.In modern use,...
epidemiologist, through his book Effectiveness and Efficiency: Random Reflections on Health Services (1972) and subsequent advocacy, caused increasing acceptance of the concepts behind evidence-based practice.
Cochrane's work was honoured through the naming of centres of evidence-based medical research — Cochrane Centres — and an international organization, the Cochrane Collaboration
Cochrane Collaboration
The Cochrane Collaboration is a group of over 28,000 volunteers in more than 100 countries who review the effects of health care interventions tested in biomedical randomized controlled trials. A few more recent reviews have also studied the results of non-randomized, observational studies...
. The explicit methodologies used to determine "best evidence" were largely established by the McMaster University
McMaster University
McMaster University is a public research university whose main campus is located in Hamilton, Ontario, Canada. The main campus is located on of land in the residential neighbourhood of Westdale, adjacent to Hamilton's Royal Botanical Gardens...
research group led by David Sackett
David Sackett
David Lawrence Sackett, OC, FRSC is a Canadian medical doctor and a pioneer in evidence-based medicine. He founded the first department of clinical epidemiology in Canada at McMaster University, and the Oxford Centre for Evidence-Based Medicine...
and Gordon Guyatt
Gordon Guyatt
Gordon Henry Guyatt is a physician and Professor of Clinical Epidemiology & Biostatistics at McMaster University in Hamilton, Ontario. He is known for his work on evidence-based medicine, a term that first appeared in a paper he published. He has published over 450 peer-reviewed articles in...
. Guyatt later coined the term “evidence-based” in 1990. The term "evidence-based medicine" first appeared in the medical literature in 1992 in a paper by Guyatt et al. Relevant journals include the British Medical Journal's Clinical Evidence, the Journal Of Evidence-Based Healthcare and Evidence Based Health Policy. All of these were co-founded by Anna Donald
Anna Donald
Anastasia Katherine "Anna" Donald was an Australian pioneer in the field of evidence-based medicine.-Education:...
, an Australian pioneer in the discipline.
EBM and ethics of experimental or risky treatments
Insurance companies in the United States and public insurers in other countries usually wait for drug use approval based on evidence-based guidelines before funding a treatment. Where approval for a drug has been given, and subsequent evidence based findings indicating that a drug may be less safe than originally anticipated, some insurers in the U.S. have reacted very cautiously and withdrawn funding. For example, an older generic statin drug had been shown to reduce mortality, but a newer and much more expensive statin drug was found to lower cholesterol more effectively. However, evidence came to light about safety concerns with the new drug which caused some insurers to stop funding it even though marketing approval was not withdrawn.Some people are willing to take their chances to gamble their health on the success of new drugs or old drugs in new situations which may not yet have been fully tested in clinical trials. However insurance companies are reluctant to take on the job of funding such treatments, preferring instead to take the safer route of awaiting the results of clinical testing and leaving the funding of such trials to the manufacturer seeking a license.
Sometimes caution errs in the other direction. Kaiser Permanente
Kaiser Permanente
Kaiser Permanente is an integrated managed care consortium, based in Oakland, California, United States, founded in 1945 by industrialist Henry J. Kaiser and physician Sidney Garfield...
did not change its methods of evaluating whether or not new therapies were too "experimental" to be covered until it was successfully sued twice: once for delaying in vitro fertilization treatments for two years after the courts determined that scientific evidence of efficacy and safety had reached the "reasonable" stage; and in another case where Kaiser refused to pay for liver transplantation in infants when it had already been shown to be effective in adults, on the basis that use in infants was still "experimental." Here again, the problem of induction plays a key role in arguments.
Application of the evidence based model on other public policy matters
There has been discussion of applying what has been learned from EBM to public policy. In his 1996 inaugural speech as President of the Royal Statistical Society, Adrian Smith held out evidence-based medicine as an exemplar for all public policy. He proposed that "evidence-based policy" should be established for education, prisons and policing policy and all areas of government.See also
- Clinical decision support systemClinical decision support systemClinical decision support system is an interactive decision support system Computer Software, which is designed to assist physicians and other health professionals with decision making tasks, as determining diagnosis of patient data. A working definition has been proposed by Dr...
(CDSS) - Consensus (medical)Consensus (medical)Medical consensus is a public statement on a particular aspect of medical knowledge available at the time it was written, and that is generally agreed upon as the evidence-based, state-of-the-art knowledge by a representative group of experts in that area...
- Cochrane CollaborationCochrane CollaborationThe Cochrane Collaboration is a group of over 28,000 volunteers in more than 100 countries who review the effects of health care interventions tested in biomedical randomized controlled trials. A few more recent reviews have also studied the results of non-randomized, observational studies...
- Dynamic treatment regimesDynamic treatment regimesIn medical research, a dynamic treatment regime or adaptive treatment strategy is a set of rules for choosing effective treatments for individual patients. The treatment choices made for a particular patient are based on that individual's characteristics and history, with the goal of optimizing...
- Evidence-based DentistryEvidence-based DentistryEvidence-based Dentistry is the concept of using current evidence to guide decision-making was first introduced by Gordon Guyatt and the Evidence-Based Medicine Working Group at McMaster University in Ontario, Canada in the 1990s...
- Evidence-based managementEvidence-based managementEvidence-based management is an emerging movement to explicitly use the current, best evidence in management decision-making. Its roots are in evidence-based medicine, a quality movement to apply the scientific method to medical practice....
- Evidence-based medical ethicsEvidence-based medical ethicsEvidence-based medical ethics is a form of medical ethics that uses knowledge from ethical principles, legal precedent, and evidence-based medicine to draw solutions to ethical dilemmas in the health care field. Sometimes this is also referred to as argument-based medical ethics. It is also the...
- Evidence-based nursingEvidence-Based NursingEvidence-Based Nursing or EBN is a type of evidence-based healthcare, drawing on some of the traditions of evidence-based medicine. It involves identifying solid research findings and implementing them in nursing practices, in order to increase the quality of patient care. The goal of EBN is to...
- Evidence-based pharmacy in developing countriesEvidence-based pharmacy in developing countriesMany developing nations have developed national drug policies, a concept that has been actively promoted by the WHO. For example, the national drug policy for Indonesia drawn up in 1983 had the following objectives:...
- Evidence based practiceEvidence based practiceEvidence-based practice is an interdisciplinary approach gaining ground after 1992. It started in medicine as evidence-based medicine and spread to other fields such as nursing, psychology, education, library and information science and other fields...
- Guideline (medical)Guideline (medical)A medical guideline is a document with the aim of guiding decisions and criteria regarding diagnosis, management, and treatment in specific areas of healthcare...
- Guidelines International NetworkGuidelines International NetworkThe Guidelines International Network is an international scientific asssociation of organisations and individuals interested and involved in development and application of evidence based guidelines and health care information...
- Hospital accreditationHospital accreditationHospital accreditation has been defined as “A self-assessment and external peer assessment process used by health care organizations to accurately assess their level of performance in relation to established standards and to implement ways to continuously improve”...
- Medical algorithmMedical algorithmA medical algorithm is any computation, formula, statistical survey, nomogram, or look-up table, useful in healthcare. Medical algorithms include decision tree approaches to healthcare treatment and also less clear-cut tools aimed at reducing or defining uncertainty.-Scope:Medical algorithms are...
- NoceboNoceboIn medicine, a nocebo reaction or response refers to harmful, unpleasant, or undesirable effects a subject manifests after receiving an inert dummy drug or placebo...
- Improvement Science Research NetworkImprovement Science Research NetworkThe ' is a large-scale practice based research network and coordinating center that was created to accelerate inter-professional improvement science in a systems context across multiple hospital sites...
General:
- Critical appraisalCritical appraisalCritical appraisal is the use of explicit, transparent methods to assess the data in published research, applying the rules of evidence to factors such as internal validity, adherence to reporting standards, conclusions and generalizability. Critical appraisal methods form a central part of the...
- Evidence-based designEvidence-based designEvidence-based design often shortened to EBD is a field of study that emphasizes the importance of using credible data in order to influence the design process. The approach has become popular in Healthcare Architecture in an effort to improve patient and staff well-being, patient healing...
- Evidence based policy
- Policy-based evidence makingPolicy-based evidence makingThe term Policy based evidence making is a pejorative term which refers to the commissioning of research in order to support a policy which has already been decided upon. The name has been suggested as a corollary to evidence based policy making....
- Quality controlQuality controlQuality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects:...
- Source criticismSource criticismA source criticism is a published source evaluation . An information source may be a document, a person, a speech, a fingerprint, a photo, an observation or anything used in order to obtain knowledge. In relation to a given purpose, a given information source may be more or less valid, reliable or...
- Systematic reviewSystematic reviewA systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
External links
- evidence.nhs.uk NHS Evidence allows everyone working in health and social care to access a wide range of health information to help them deliver quality patient care. Launched in April 2009, NHS Evidence: has a fast, free and easy to use search engine to help users search for the information they want. Ranks search results from credible medical sources according to relevance and quality. Allows users – through My Evidence — to personalise a search and register to receive the latest health information alerts. Awards an Accreditation Mark to organisations who meet high quality standards in developing health information
- Institute of MedicineInstitute of MedicineThe Institute of Medicine is a not-for-profit, non-governmental American organization founded in 1970, under the congressional charter of the National Academy of Sciences...
Forum on Evidence Based Medicine' The IOM Roundtable on Evidence-Based Medicine brings together key stakeholders from multiple sectors—patients, health providers, payers, employers, manufacturers, policy makers, and researchers—for cooperative consideration of the ways that evidence can be better developed and applied to drive improvements in the effectiveness and efficiency of medical care in the United States. - Cochrane.org — 'The Cochrane Collaboration: The reliable source for evidence in healthcare' (systematic reviewSystematic reviewA systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
s of the effects of health care interventions), Cochrane LibraryCochrane LibraryThe Cochrane Library is a collection of databases in medicine and other healthcare specialties provided by the Cochrane Collaboration and other organisations. At its core is the collection of Cochrane Reviews, a database of systematic reviews and meta-analyses which summarize and interpret the...
Major source of rigorous EBM evaluations. - AHRQ.gov — 'U.S. Preventive Services Task Force (USPSTF)', Agency for Health Care Research and Quality. Major source of EBM evaluations
- 'What Is Evidence-Based Medicine?' — American College of CardiologyAmerican College of CardiologyThe American College of Cardiology is a nonprofit medical association established in 1949 to advocate for quality cardiovascular care through education, research promotion, development and application of standards and guidelines, and to influence health care policy...
- GPNoteBook.co.uk — 'Evidence-based medicine (EBM)', General Practice Notebook Free content
- JR2.ox.ac.uk — 'Bandolier: Evidence-based thinking about health care', BandolierBandolier (journal)Bandolier is an independent online electronic journal about evidence-based healthcare, written by Oxford University scientists. It was started in 1994 and the National Health Service paid for its distribution to all doctors in the UK until 2002. Publication of the printed version ceased in 2007 and...
Free reviews online - SHEF.ac.uk — 'Netting the Evidence: A ScHARR Introduction to Evidence Based Practice on the Internet' (resource directory), University of SheffieldUniversity of SheffieldThe University of Sheffield is a research university based in the city of Sheffield in South Yorkshire, England. It is one of the original 'red brick' universities and is a member of the Russell Group of leading research intensive universities...
Extensive bibliographies and links to online articles - TRIP Database — 'TRIP Database — EBM search engine' (resource directory), TRIP Knowledge Service. Free. (Editorial) (Education and debate)
- CEBM.net — OxfordOxfordThe city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...
Centre for Evidence-Based Medicine (UK) Some free content (Classic argument that situations still exist where RCTs are unnecessary.) - EBOnCall.org — 'Evidence compendia' (evidence-based summaries of 38 on-call medical conditions), Evidence-Based On-Call (EBOC) Free
- www.ebpom.org — Evidence Based Perioperative Medcicine
- DBSkeptic.com The limits of evidence-based medicine
- ProfessorEBM.com Evidence-based teaching guides for over 80 common internal medicine conditions
- The Users’ Guides to the Medical LiteratureUsers’ Guides to the Medical LiteratureThe Users’ Guides to the Medical Literature is a series of articles originally published in the Journal of the American Medical Association, now rewritten and compiled in a textbook format...
are a series of journal articles and more recently a comprehensive textbook, that provide invaluable tips for clinicians wishing to incorporate evidence-based medicine into their practices. - Improvement Science Research Network