Teaching evidence-based medicine
Robert G. Badgett, M.D.
Teaching evidence based medicine (EBM) is essential and core competencies have been recommended.
Most of this article is about teaching evidence-based individual decision making and not about evidence-based medicine at the institutional level. This first part of this article covers studies or reports of methods in EBM. The second part reviews studies on the effectiveness of teaching evidence-based medicine. Both sections may guide the teacher of EBM in selecting strategies, but the teacher should note that only ideas on the second section have empiric data on effectiveness.

# Methods for teaching EBM
A multinational European group has used the Delphi method to design a comprehensive EBM course based on five steps of EBM. The course is clinically integrated. Its effectiveness is at least as good as traditional teaching. Their proposed  learning objectives are available online:
- 'generate structured questions arising from clinical problems in practice'
- 'search relevant literature, identifying systematic reviews wherever possible'
- 'assess the quality (validity) of systematic reviews and primary research included within them'
- 'assess the applicability of research findings in clinical practice'
- 'effectively implement the output from above activities into clinical practice'
The 6Ts Teaching Tips have been recommended by experienced teachers of evidence-based medicine:
- Time management. Plan in advance how class time will be used.
- Teamwork. Encourage all of the class to participate.
- Tools. Use audio, visual, and multimedia to improve learning.
- Triage. Be prepared to triage class content and to eliminate content if time is short.
- Tone. Create a respectful and non-threatening tone in the class.
- Take home messages. End with take home messages.

## Formulation of the clinical question ('PICO')
The 'PICO' format, which is mnemonic for:
- P - patients, problems, or population
- I - intervention, exposure, or test
- C - comparison
- O - outcome
Although PICO cannot represent all clinical question, especially questions that are not about interventions, use of PICO may improve the precision of searches.

## Search strategies
A strategy for information retrieval similar to the 5S strategy should be taught for use when the searcher has limited time available during clinical care. This is based on one positive study of its use and two negative studies of teaching the use using secondary and primary publications. In addition, indirect evidence on the time needed to search also supports the emphasis on using tertiary publications. Doctors may have two minutes available to search, whereas using MEDLINE may take 20 minutes or more.
Teaching MEDLINE searching would be appropriate for Doers who might be willing to invest time in searching MEDLINE when not hurried by clinical care. Based on studies of common errors in searching MEDLINE, learners should be taught Medical Subject Headings (MeSH) terms and their explosion, appropriate limits, and best evidence to search for. The mnemonic PEARL may guide how to each. PEARL stands for:
- "Choose a 'Preplanned search intervention'"
- "Allow learners to 'Execute the search,' thus committing themselves"
- "'Allow learners to teach other learners' about their search process
- "'Review the quality of evidence' for the information found"
- "Discuss 'Lessons of the search.'"
A subsequent negative study has been published about the effect of a single session of learning to search.

## Critical appraisal
It is very common to read only the abstract of an article. However, many abstracts contain errors compared to the body of the article. Fortunately, these are usually errors of omission rather than contradiction.
One strategy for teaching critical appraisal has been to make a goal of a journal club include the goal "composing, editing, and submitting a  letter to the editor

## Clinical reasoning
There are various methods of clinical reasoning include probabilistic (Bayesian), causal (physiologic), and deterministic (rule-based).  In addition, medical experts rely more on pattern recognition which is faster; however, clinical experts seem flexible and may use whichever method of reasoning most easily represents and solves a given problem. When confronted with non-challenging cases physicians may use 'nonanalytical reasoning' such as pattern recognition; however, during more difficult cases physicians may switch to 'reflective reasoning'. Reflective reasoning may especially help complex cases. Explicit Bayesian thinking with precise numbers is rarely done. Basic science knowledge is probably "encapsulated" into clinical knowledge.
Successfully distilling complex information into a short summary, perhaps using semantic qualifiers, may help diagnostic accuracy.
Possible strategies to improve clinical reasoning have been reviewed and using problem-based learning, include teaching appropriate problem representation creating a one-sentence summary of a case, standardized patients, teaching hypothetico-deductive reasoning, cognitive forcing strategies to avoid premature closure, teaching the competing-hypotheses heuristic, using fuzzy-trace theory and mixed-methods interventions. Studies are unclear about  teaching logic. Regarding hypothetico-deductive reasoning, an observational study on the methods used by experts solving clinicopathological exercises reported that these experts use the following six steps:
- aggregation of groups of findings into patterns
- selection of a "pivot" or key finding
- generation of a cause list
- pruning of the cause list
- selection of a diagnosis
- validation of the diagnosis
Scales to measure clinical reasoning have been proposed.

### Numeracy
Various methods have been proposed for improving quantitative literacy. For diagnosis, likelihood ratios or sensitivity and specificity are two methods. It is unclear which method is better according to the results of a controlled trial.
Studies are inconclusive on using cognitive feedback..
Framing bias is best avoided by using numeracy with absolute measures of efficacy.

# Assessing the teaching of evidence-based medicine
Two systematic reviews of EBM provide the framework below for measuring outcomes. Two instruments, the Berlin questionnaire and the Fresno test are the most validated. These questionnaires have been used in diverse settings. The Fresno test is more thorough but the Berlin Questionnaire is easier to administer.

# Studies of the effectiveness of teaching evidence-based medicine
A systematic review of the effectiveness of teaching EBM concluded "standalone teaching improved knowledge but not skills, attitudes or behaviour. Clinically integrated teaching improved knowledge, skills, attitudes and behaviour." A second review concluded improvements in unvalidated measures of "knowledge, skills, attitudes or behavior." Neither review examined improvements in clinical care.

## 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 which 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 the long term.
A randomized controlled trial studied the effect of a searching tutorial that met for up to 6 1-hour small group sessions to search for answers to questions about their hospitalized patients. The intervention did not improve their success or speed in completing an Objective Structured Searching Evaluation (OSSE).
An evidence-based medicine course consisting of six 2-hour workshop sessions shifted the types of resources learners used during a patient vignette.

### Improving clinical care
Teaching "user" mode only using syntheses and synopses, without summaries, has not shown benefit in two studies. 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. A quasi-randomized, controlled investigation of teaching medical students the use of studies, syntheses, and synopses using an automated search engine was negative.

## Information awareness
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."
No controlled studies have addressed improving clinical care by use of information awareness strategies.
A controlled trial of teaching Bayes Theorem (probabilistic reasoning) "improves the efficiency of test ordering."

## Clinical reasoning
Teaching Bayesian understanding of diagnostic testing improved actual test ordering in a controlled trial.
Improving physicians' probability judgments did not lead to improvements in clinical decision making in a controlled before and after study.
Encouraging the use of reflecting reasoning by suggesting to diagnosticians that a case is especially difficult may improve diagnositc accuracy.
Teaching the SNAPPS method of student and preceptor interaction may help:
- Summarize history and findings
- Narrow the differential
- Analyze the differential
- Probe preceptor about uncertainties
- Plan management
- Select case-related issues for self-study

## Critical appraisal
There are no studies that teaching critical appraisal (including journal clubs), in isolation, improves clinical care. A systematic review was inconclusive whether journal clubs improved information habits.
However, randomized controlled trials have found that the READER model (Relevance, Education, Applicability, Discrimination, overall Evaluation) and other methods increase the critical appraisal skills of learners.
If being a successful journal club is defined as one that has high attendance or is long-standing, then successful attributes are "associated with smaller residency programs, making attendance  mandatory, promoting a journal club independent of faculty,  providing formal teaching of critical appraisal skills, making food available,  and emphasizing original research articles."