EBM is defined as “the conscientious, explicit and judicious use of the current best evidence in making decisions about the care of individual patients.” Essentially, EBM is a method of making clinical decisions by integrating clinical expertise, patient’s preferences, circumstances and values, and judicious application of the best available research evidence.

The steps involved in EBM are: (a) formulating a focused and answerable clinical question; (b) identifying the “best evidence” (articles, studies) to answer the question; (c) appraising (reading and analyzing) the studies critically; and (d) integrating the evidence with clinical expertise, patient’s (parents’) values, preferences, and circumstances.

Background questions (why, what, when, how, who) ask about the general knowledge of a disease and can be answered using textbooks and classical review articles. An example of a background question is “What are the complications of gastroesophageal reflux disease?” Foreground questions, however, are answered using EBM skills. The four essential components of foreground questions have been given the acronym PICO: Patient and/or problem (P), the intervention (I), comparison intervention (if relevant) (C), and clinical outcomes (O). The outcomes should be “patient-oriented outcomes that matter” rather than “disease-oriented outcomes.” An example of a foreground question is “In a 6-month-old infant with gastro-esophageal reflux, do prokinetic agents reduce the frequency of vomiting?”

Clinical foreground questions fall into four categories: therapy (intervention), harm (etiology), diagnosis, and prognosis. A hierarchical classification of evidence according to its strength has been proposed: For example, the hierarchy of evidence regarding therapy questions ranges from unsystematic clinical observations at the bottom (weakest) to systematic reviews at the top (strongest).

The type of question, the topic, and the time available determine the selection of an evidence source. To answer general background clinical questions, a well-referenced and regularly updated textbook is recommended. However, for focused fore-ground therapy questions, prefiltered, evidence-based resources (e.g., Clinical Evidence, Cochrane Library) are preferred.

Until recently, EBM was a technical, time consuming, and labor intensive endeavor that few physicians had the interest, skills, and will to pursue. But today, with new technologies, many excellent EBM resources are available on the Internet, making EBM more accessible and “doable” in daily medical practice (Box 4.1).

Because the volume of material is large and time is limited, a method is necessary to identify which articles are worth screening and which among those screened are worth appaising critically. The two major types of studies reported in the medical literature are (a) primary or analytic and (b) secondary or integrative. Primary studies, which can be observational, experimental, or interventional, report original research. Box 4.2 depicts the classification of research designs in primary studies. Secondary (integrative) studies summarize or draw conclusions from the original research (systematic reviews, meta-analyses, clinical guidelines).

A number of formats, guides, questions, checklists, and resources are available for critically appraising the medical literature (Boxes 4.3, 4.4 and 4.5 and Table 4.1). One of the more user-friendly and popular is the Users’ Guides to the Medical Literature, developed by Haynes, Sackett, and Tugwell at McMaster University, Canada. These guides, initially published in The Journal of the American Medical Association, have been revised and compiled in a textbook. Other formats include the traditional pre-EBM journal club method and the “How to Read a Paper” series by Greenhalgh, initially published in The British Medical Journal and now compiled in a textbook. The Consolidated Standards of Reporting Trials (CONSORT) statement is a checklist for writing, reviewing, and evaluating reports of parallel-group randomized clinical trials. Recently, the Quality of Reports of Meta-analyses (QUOROM) statement was developed and published to improve the quality of the reporting of meta-analyses of randomized controlled trials.

The basic structure of a medical journal article is shown in Box 4.6. Critical appraisal, an essential component of EBM, is a method of assessing the validity, results, and relevance of a medical journal article. The following is offered as one approach to reading the medical literature, based on a series of questions.