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Analyzing the Evidence in the Literature: Introduction
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The third element in the effective integration of evidence-based principles into physical therapist practice is the use of scientifically derived evidence. Over the past two decades, studies suggest that health-care practitioners have difficulty changing their methods of practice from those they were taught in school and in enhancing their knowledge with newly developed scientific findings. Accessing and evaluating the quality of scientific evidence has become a challenge for busy practitioners. Each year brings new and better tools to help clinicians integrate evidence into their clinical practice.
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Although there are numerous excellent textbooks available for physical therapists with an in-depth approach to accessing and evaluating scientific evidence, this section of our text will present a broader perspective on integrating evidence. We are strongly influenced in our framework for this section by the work of R. Brian Haynes, who has recommended a hierarchical model for organizing information of value to clinicians in making clinical decisions.1,2 The pyramidal format (Fig. 1) is based on the relative value of various sources of evidence to clinicians. It is not based on the strength of the original evidence, such as the pyramid found in Chapter 11 of this section, but is based upon the value-added aspects that come with filtered and enhanced sources of evidence. Haynes' evidence pyramid acknowledges the value to the clinician when evidence from single studies has undergone secondary review and synthesis by experts.
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Haynes recommends that clinicians work from the top down in this model, trying first to obtain the most limited but the most valuable of the evidence-based information sources available to them. In presenting the chapters in this section, we will work from the bottom of the pyramid, which is more familiar to most and where the volume of available resources is greatest, and then move upward.
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Chapter 10 sets out the first step in using any source of evidence, asking a sound clinical question that is based on the needs of patients and the judgment of the clinician. These questions guide the search for new knowledge about the diagnosis, prognosis, or treatment of patients. Knowing what you are looking for in the evidence will enhance the likelihood that the evidence you find will fit your purpose. In Chapter 11, Connie Schard discusses current resources and methods to access unfiltered evidence contained in original scientific studies. The chapter also describes access to databases of filtered syntheses, synopses, and summaries. Chapter 12 reviews the value of original experimental research by highlighting the methodological and statistical principles that represent ...