Monday, February 1, 2010

How to Find the Best Evidence

Keeping up with the current best evidence is a difficult process for all of us. New knowledge is expanding at a frightening rate, and it is easy for us to become overwhelmed by it. The authors of the small text Evidence-Based Medicine: How to Practice and Teach EBM (1) suggest that one method by which we can remain up-to-date is to use a form of “learning by inquiry.” This is based on the idea that when we are confronted with a clinical question where we are unsure of the answer, we develop methods for finding the current best answer as efficiently as possible. The authors remind us that there is a hierarchy of evidence that exists, which they base on the concept of the 4S (see below). We need to be able to develop a clinical question which will also allow us to do an efficient and effective search, no matter that the search is done on a web-based database or simply by hand searching a textbook or pocket manual. With regard to orienting ourselves to evidence-based information sources, the authors suggest the following:

1. Burn your traditional textbooks. This hurts, of course, because I have developed and published textbooks, but I also recognize the truth here. I know that the first textbook I wrote took 4 years to complete; by the time I was done, it was out of date. And this is endemic to most textbook publishing. But part of the problem is that not everything in the text is out of date; just some of it is. But we don’t know which parts, making it a less trustworthy source of clinical information. They note that textbooks are good at answering what are called “background” questions, questions such as, say, information about pathophysiology, but they are not good at “foreground” questions concerning causal factors, risks, and management.

2. Take a “4S” approach to evidence-based information. They note the rapid evolution of information services occurring at present. Thus, they suggest noting the presence of a 4S hierarchical structure, where studies lie at the base of a pyramid, with syntheses on top of that, synopses higher yet, and systems at the pinnacle. You should always try to locate information that will answer your question that is located at the highest level of this pyramid. A system would “integrate and concisely summarize all relevant and important research evidence about a clinical problem” and would help link you to the relevant information. Systems do not tell you what to do, but need to be integrated with the specifics of the patient’s situation. Some systems do exist; one noted in the text is Clinical Evidence (, also available in Ovid). PIER (Physician’s Information and Evidence Resource)is another (http://pier.acponline.,org/index.html). These are, unlike textbooks, regularly updated. Synopses are reviews of individual studies and reviews. A perfect synopsis would provide just the information you need to support your clinical action. A synthesis is useful when no systems or synopses are available. The Cochrane database is one example of a repository of syntheses. These look for evidence and then summarize the findings.Finally, studies are, of course, individual pieces of research on a topic. If no systems, synopses or syntheses exist, one can rely on studies to help guide action.

3. Organize access to evidence-based information services. Most of the references we use can be found on the internet. And because we work at an academic institution, we are provided access to a rich database of resources, but we need to keep mindful that not all of these resources are useful or appropriate for our needs. We have to determine what we want. And for those not in academia, they may be limited to open access resources such as Biomed Central (, which offers access to all its publications at no cost to the consumer.

4. Is it time to change how you seek best evidence? How many of us use the 4S approach? How often is that instead we use the basic idea that systematic reviews are the pinnacle of information we need? Can we change our behavior to use better resources?

This is simply a guide to doing just that, to looking at the use of systems as the pinnacle of information seeking for clinical guidance.

1. Struas S, Richardson WS, Glasziou P, Haynes RB. Evidence-Based Medicine: How to Practice and Teach EBM, 3rd edition. New York, NY: Elsevier, 2005:31

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