Brief review of evidence-based medicine | Evidence-based literature sources
Brief review of evidence-based medicineThe practice of evidence-based medicine has traditionally been defined as combining the best medical research findings with clinical judgment, expertise and experience. As the EBM concept has evolved, other key factors affecting clinical decision-making have been identified. The clinical setting, state and circumstances, as well as the individual preferences and values of the patient, are seen as playing a crucial role in decisions about patient care (Haynes, Devereaux, & Guyatt, 2002). Locating the best research evidence from the medical literature is a critical part of this complex process. “The systematic approach underlying EBM encourages the clinician to formulate specific and relevant questions, which are answered in an iterative manner through accessing the best available published evidence.” (Landry & Sibbald, 2001) Advances in research have produced a rich archive of patient-centered literature on the effectiveness of treatment options, the accuracy of diagnostic tools and the reliability of prognostic markers. With over 2 million articles published each year in about 20,000 biomedical journals, it has become more and more important to find efficient ways to locate the best evidence in a timely manner. According to Gordon Guyatt, “evidence may be published in a wide variety of sources, including original journal articles, reviews and synopses of primary studies, practice guidelines and traditional and innovative medical textbooks” (Guyatt, Rennie, Evidence-Based Medicine Working Group & American Medical Association, 2002). Many new information resource tools have been developed to help select out the most valuable evidence from this large and diverse collection of medical information. However, deciding how to choose the best resource to provide immediate answers to clinical questions remains a major challenge for the busy practitioner.
Evidence-based literature sourcesWhat EBM literature sources are available? The short answer is lots! Some resources, such as the Cochrane Database of Systematic Reviews, are well recognized and widely known. Others, such as PIER, are more specialized and still under development. To further complicate the picture, the “evidence-based” label has been applied to resources that use a variety of approaches and selection methods. Content ranges from original systematic reviews with thoroughly documented methodologies (such as Cochrane) to well-referenced topical summaries with loosely defined literature selection methods (UpToDate). Choosing an EBM literature sourceWhen faced with a clinical situation, how do you decide which of the many evidence-based literature resources to use? How do you assess the value and relative merits of these sources? Those decisions usually depend both on the time you have available and, most importantly, the nature of the question itself. Before turning to an abstracting service, a textbook, a review database or the primary research literature, it is important to analyze your clinical question. While somewhat simplistic, it can be useful to think about the idea of background versus foreground questions.
Categories of Clinical QuestionsTo summarize, think of these categories when you are faced with a clinical question: Background questions: use a reliable textbook such as Harrison’s Online for this kind of information. While based on expert opinion, a text such as Harrison’s is thoroughly referenced and regularly peer-reviewed. Another “textbook-like” resource, UpToDate, provides current, peer-reviewed topical summaries supported by selected references from the medical research literature. Foreground questions: use a “pre-filtered” EBM resource such as the Cochrane Database of Systematic Reviews or the ACP Journal Club to help answer this type of question. These resources select, analyze and summarize studies that are considered both methodologically sound and clinically relevant. The drawback here is the limited number of clinical topics that are covered in these pre-filtered resources. So you might also need to consult the primary literature for a foreground question. Questions involving the need for primary research literature: search the MEDLINE database for an original research article to address a more specialized clinical situation. There is one very important point to keep in mind, though: all of the articles included in MEDLINE are not evidence-based. Special search strategies and techniques are needed to filter through the millions of MEDLINE references to find patient-centered, systematically researched studies. One good option is using the built-in search filters known as PubMed Clinical Queries. Resources Examined in this TutorialWe will concentrate on using four of the key evidence-based resources:
Note: In the above table, click on the left-column names to go to the corresponding section in this tutorial. Click on the logos in the right column to view the Websites of the resources. We will look at what each resource has to offer and specific searching strategies using a sample clinical scenario. These four tools have been selected both for their recognized quality and to demonstrate options for locating background and foreground evidence-based literature. However, as we have pointed out previously, many, many other resource choices are available. For more information on these other choices, you may want to consult this detailed EBM Resource table or refer to some of the Resource Links sites listed at the end of this tutorial. |
