The Evidence-Based Practice Movement


The Cochrane Collaboration was an early contributor to the EBP movement. The collaboration was founded in the United Kingdom based on the work of British epidemiologist Archie Cochrane. Cochrane published an influential book in the 1970s that drew attention to the dearth of solid evidence about the effects of health care. He called for efforts to make research summaries of clinical trials available to health care providers. This eventually led to the development of the Cochrane Center in Oxford in 1993, and an international partnership called the Cochrane Collaboration, with centers established in locations throughout the world. Its aim is to help providers make good decisions about health care by preparing and disseminating systematic reviews of the effects of health care interventions.

At about the same time, a group from McMaster Medical School in Canada (including Dr. David Sackett) developed a clinical learning strategy they called evidence-based medicine. The evidence-based medicine movement has shifted to a broader conception of using best evidence by all health care practitioners (not just physicians) in a multidisciplinary team. EBP is considered a major shift for health care education and practice. In the EBP environment, a skillful clinician can no longer rely on a repository of memorized information but rather must be adept in accessing, evaluating, and using new evidence.

The EBP movement has advocates and critics. Supporters argue that EBP is a rational approach to providing the best possible care with the most cost-effective use of resources. Advocates also note that EBP provides a framework for self-directed lifelong learning that is essential in an era of rapid clinical advances and the information explosion. Critics worry that the advantages of EBP are exaggerated and that individual clinical judgments and patient inputs are being devalued. They are also concerned that insufficient attention is being paid to the role of qualitative research. Although there is a need for close scrutiny of how the EBP journey unfolds, an EBP path is the one that health care professions will almost surely follow in the years ahead.

TIP: A debate has emerged concerning whether the term “evidence-based practice” should be replaced with evidence-informed practice (EIP). Those who advocate for a different term have argued that the word “based” suggests a stance in which patient values and preferences are not sufficiently considered in EBP clinical decisions (e.g., Glasziou, 2005). Yet, as noted by Melnyk (2014), all current models of EBP incorporate clinicians’ expertise and patients’ preferences. She argued that “changing terms now … will only create confusion at a critical time where progress is being made in accelerating EBP” (p. 348). We concur and we use EBP throughout this book.

Knowledge Translation

Research utilization and EBP involve activities that can be undertaken at the level of individual nurses or at a higher organizational level (e.g., by nurse administrators), as we describe later in this chapter. In the early part of this century, a related movement emerged that mainly concerns system-level efforts to bridge the gap between knowledge generation and use.  Knowledge translation (KT)  is a term that is often associated with efforts to enhance systematic change in clinical practice.

It appears that the term was coined by the Canadian Institutes of Health Research (CIHR) in 2000. CIHR defined KT as “the exchange, synthesis, and ethically-sound application of knowledge—within a complex system of interactions among researchers and users—to accelerate the capture of the benefits of research for Canadians through improved health, more effective services and products, and a strengthened health care system” (CIHR, 2004, p. 4).

Several other definitions of KT have been proposed. For example, the World Health Organization (WHO) (2005) adapted the CIHR’s definition and defined KT as “the synthesis, exchange and application of knowledge by relevant stakeholders to accelerate the benefits of global and local innovation in strengthening health systems and improving people’s health.” Institutional projects aimed at KT often use methods and models that are similar to institutional EBP projects.

TIP: Translation science (or implementation science) has emerged as a discipline devoted to developing methods to promote knowledge translation. In nursing, the need for translational research was an important impetus for the development of the Doctor of Nursing Practice degree. Several journals have emerged that are devoted to this field (e.g., the journal Implementation Science).


Before describing procedures relating to EBP in nursing, we briefly discuss some important issues, including the nature of “evidence” and challenges to pursuing EBP, and resources available to address some of those challenges.

Types of Evidence and Evidence Hierarchies

There is no consensus about the definition of evidence nor about what constitutes usable evidence for EBP, but most commentators agree that findings from rigorous research are paramount. Debate continues, however, about what constitutes rigorous research and what qualifies as best evidence.

At the outset of the EBP movement, there was a strong bias toward reliance on information from studies called randomized controlled trials (RCTs). This bias stemmed from the fact that the Cochrane Collaboration initially focused on the effectiveness of therapies rather on other types of health care questions. RCTs are, in fact, very well suited for drawing conclusions about the effects of health care interventions ( Chapter 9 ). The bias in ranking sources of evidence in terms of questions about effective treatments led to some resistance to EBP by nurses who felt that evidence from qualitative and non-RCT studies would be ignored.

Positions about the contribution of various types of evidence are less rigid than previously. Nevertheless, many published  evidence hierarchies  rank evidence sources according to the strength of the evidence they provide, and in most cases, RCTs are near the top of these hierarchies. We offer a modified evidence hierarchy that looks similar to others, but ours illustrates that the ranking of evidence-producing strategies depends on the type of question being asked.

Figure 2.1  shows that  systematic reviews  are at the pinnacle of the hierarchy (Level I), regardless of the type of question, because the strongest evidence comes from careful syntheses of multiple studies. The next highest level (Level II) depends on the nature of inquiry. For Therapy questions regarding the efficacy of an intervention (What works best for improving health outcomes?), individual RCTs constitute Level II evidence (systematic reviews of multiple RCTs are Level I). Going down the “rungs” of the evidence hierarchy for Therapy questions results in less reliable evidence—for example, Level III evidence comes from a type of study called quasi-experimental. In-depth qualitative studies are near the bottom, in terms of evidence regarding intervention effectiveness. (Terms in  Figure 2.1  will be discussed in later chapters.)



Evidence hierarchy: levels of evidence.

For a Prognosis question, by contrast, Level II evidence comes from a single prospective cohort study, and Level III is from a type of study called case control (Level I evidence is from a systematic review of cohort studies). Thus, contrary to what is often implied in discussions of evidence hierarchies, there really are multiple hierarchies. If one is interested in best evidence for questions about Meaning, an RCT would be a poor source of evidence, for example. We have tried to portray the notion of multiple hierarchies in  Figure 2.1 , with information on the right indicating the type of individual study that would offer the best evidence (Level II) for different questions. In all cases, appropriate systematic reviews are at the pinnacle. Information about different hierarchies for different types of cause-probing questions is addressed in  Chapter 9 .

Of course, within any level in an evidence hierarchy, evidence quality can vary considerably. For example, an individual RCT could be well designed, yielding strong Level II evidence for Therapy questions, or it could be so flawed that the evidence would be weak.

Thus, in nursing, best evidence refers to research findings that are methodologically appropriate, rigorous, and clinically relevant for answering persistent questions—questions not only about the efficacy, safety, and cost-effectiveness of nursing interventions but also about the reliability of nursing assessment tests, the causes and consequences of health problems, and the meaning and nature of patients’ experiences. Confidence in the evidence is enhanced when the research methods are compelling, when there have been multiple confirmatory studies, and when the evidence has been carefully evaluated and synthesized.

Of course, there continue to be clinical practice questions for which there is relatively little research evidence. In such situations, nursing practice must rely on other sources—for example, pathophysiologic data, chart review, quality improvement data, and clinical expertise. As Sackett and colleagues (2000) have noted, one benefit of the EBP movement is that a new research agenda can emerge when clinical questions arise for which there is no satisfactory evidence.

Evidence-Based Practice Challenges

Nurses have completed many studies about the use of research in practice, including research on barriers to EBP. Studies on EBP barriers, conducted in several countries, have yielded similar results about constraints on clinical nurses. Most barriers fall into one of three categories: (1) quality and nature of the research, (2) characteristics of nurses, and (3) organizational factors.

With regard to the research, one problem is the limited availability of high-quality research evidence for some practice areas. There remains an ongoing need for research that directly addresses pressing clinical problems, for replication of studies in a range of settings, and for greater collaboration between researchers and clinicians. Another issue is that nurse researchers need to improve their ability to communicate evidence, and the clinical implications of evidence, to practicing nurses.

Nurses’ attitudes and education are also potential barriers to EBP. Studies have found that some nurses do not value or know much about research, and others simply resist change. Fortunately, many nurses do value research and want to be involved in research-related activities. Nevertheless, many nurses do not know how to access research evidence and do not possess the skills to critically evaluate research findings—and even those who do may not know how to effectively incorporate research evidence into clinical decision making. Among nurses in non-English-speaking countries, another impediment is that most research evidence is reported in English.

Finally, many of the challenges to using research in practice are organizational. “Unit culture” can undermine research use, and administrative and other organizational barriers also play a major role. Although many organizations support the idea of EBP in theory, they do not always provide the necessary supports in terms of staff release time and availability of resources. Nurses’ time constraints are a crucial deterrent to the use of evidence at the bedside. Strong leadership in health care organizations is essential to making evidence-based practice happen.


The translation of research evidence into nursing practice is an ongoing challenge, but resources to support EBP are increasingly available. We urge you to explore other ideas with your health information librarian because the list of resources is growing as we write.

Preappraised Evidence

Research evidence comes in various forms, the most basic of which is in individual studies.  Primary studies  published in professional journals are not preappraised for quality or use in practice.  Chapter 5 discusses how to access primary studies for a literature review.

Preprocessed (preappraised) evidence is evidence that has been selected from primary studies and evaluated for use by clinicians. DiCenso and colleagues (2005) have described a hierarchy of preprocessed evidence. On the first rung above primary studies are synopses of single studies, followed by systematic reviews, and then synopses of systematic reviews. Clinical practice guidelines are at the top of the hierarchy. At each successive step in the hierarchy, the ease in applying the evidence to clinical practice increases. We describe several types of preappraised evidence sources in this section.

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