Evidence-based practice (EBP) has been defined as the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. Evidence-based practice integrates all the knowledge that the health professional has attained through

• formal education
• personal experience
• the experience of mentors and other colleagues
• the results of relevant clinical studies that have been reported in the literature.

Another important component of evidence-based practice is that it takes into account the preferences and wishes of the patient.

Nurses generally do not have the same level of autonomy as physicians in making decisions about patient care. Therefore, nurses may use the evidence-based approach more as a way to determine certain areas of care that might be good candidates for research, or for a change of treatment protocol.

In many ways, evidence-based practice is really an extension of the idea of critically evaluating resources, as discussed in Section V. A health professional who is able to search for relevant studies in the literature, critically appraise those studies, and apply the results of that appraisal in the treatment of a patient, is practicing evidence-based health care.

Evidence-based practice has also been described in terms of a five-step process that begins and ends with the patient. The five steps are as follows:

1. Construct a relevant, answerable question derived from a clinical case--that is, from a patient.

An effective EBP search begins with a clear idea as to the type of information you are looking for. You can start this thought process by applying a set of questions to the clinical problem. One method of asking yourself these questions is called PICO, an acronym for:

P--Patient or population. How would you describe the patient in terms of age, sex, race, past medical history, or other personal characteristics?

I--Intervention. What sort of action do you wish to explore--a treatment or therapy, a diagnostic test, a screening procedure, etc.?

C--Comparison. To what do you want to compare your proposed course of action--doing nothing, placebo, the current "gold standard" diagnostic tool or treatment, or some other intervention?

O--Outcomes. What is the effect of the intervention--higher or lower rate of cure, decreased or increased likelihood of a particular side effect, mortality after a particular time period, more or fewer subsequent hospitalizations?

There are many books and websites with information about constructing good clinical questions. Among the many books owned by Perry Library that you might find helpful is

Melnyk, Bernadette Mazurek and Ellen Fineout-Overholt (2005). Evidence-Based Practice in Nursing & Healthcare : a Guide to Best Practice. Philadelphia : Lippincott Williams & Wilkins.
This book has a chapter devoted to "Asking Compelling Clinical Questions."

The Duke University Medical Center Library and the Health Sciences Library at UNC-Chapel Hill have produced an excellent tutorial on EBP that you may wish to go through in its entirety. The section on "The Well-Built Clinical Question" is particularly worthwhile.

2. Select the appropriate resource(s) and conduct a search of the literature for external evidence to incorporate with your existing knowledge.

Information providers have developed a number of products that allow health professionals to search the literature of their fields for evidence-based articles and literature reviews. Evidence-based literature exists in a hierarchy from single studies, to synopses of single studies, to syntheses, to synopses of syntheses, to systems at the highest level. Depending on your particular clinical question, the resources available at one level of the hierarchy may be better suited to your need than those at another level.

• EBP Databases: The Cochrane Collaboration, an international not-for-profit organization, has developed several databases that allow users to search the evidence-based literature. These are:
  
  
  --Cochrane Database of Systematic Reviews
  --Cochrane Central Register of Controlled Trials
  --Database of Abstracts of Reviews of Effects (DARE)
  --ACP Journal Club
  
  For the Cochrane Database of Systematic Reviews, the database producer contracts with a group of reviewers to develop a literature search strategy or "protocol" on a specific topic. Once the proposed search protocol is accepted, the reviewers conduct the search and write a "review" of the clinical studies retrieved by the search. In the review, the authors discuss and compare the results of clinical trials, and attempt to discriminate between research studies that are of high quality and those that may contain flaws in design or interpretation.
  
  The Cochrane Central Register of Controlled Trials (CCTR) is an indexing and abstracting service covering journal articles that report or otherwise discuss the results of individual clinical trials. For trials that are currently being conducted, the database offers information on the stages that have been completed and that are now underway. CCTR contains over 300,000 bibliographic references to controlled trials in health care.
  
  Cochrane's Database of Abstracts of Reviews of Effects (DARE) is a Full Text database containing critical assessments of systematic reviews from a variety of medical journals. DARE consists of structured abstracts of systematic reviews from all over the world. DARE records cover topics such as diagnosis, prevention, rehabilitation, screening, and treatment.
  
  The ACP Journal Club Collection consists of two journals, ACP Journal Club, a publication of the American College of Physicians, and Evidence-Based Medicine, a joint publication with the British Medical Journal Group. The editors screen the top clinical journals to identify studies that are both methodologically sound and clinically relevant. They write an enhanced abstract of the chosen articles and provide a commentary on the value of the article for clinical practice.
  
  Finally, Cochrane's Evidence-Based Reviews Multifile allows you to search all of the Cochrane databases simultaneously, so that you can discover evidence-based literature at all levels of the hierarchy.

Outside of the Cochrane products, there are a number of methods for searching other bibliographic databases to identify journal articles with a strong basis in clinical evidence. These methods include:

• EBP Filters for Abstracting & Indexing Databases: Medical librarians and other informatics specialists have developed "filters" that can be applied to an indexing and abstracting database (such as CINAHL or Medline). The filter executes a pre-designed search strategy containing EBP terms that can be added to a keyword search for any disease, medical condition, patient age group, etc. For example, PubMed (the public version of Medline) has PubMed Clinical Queries with filters you can use to search for etiology, diagnosis, therapy, prognosis, or clinical prediction guidelines.

• EBP Subject Headings Searches: The CINAHL database uses "evidence-based" as a subject heading, so you can do a search for that term as "Word in Subject Heading."

• EBP Limit Searches: CINAHL also allows you to "Limit your results" to an Area of Interest, one of which is Evidence-based Practice.
  
  
• Journals: There are now a number of scholarly journals devoted entirely to publishing articles on evidence-based practice.
  

Once you have conducted your search and identified literature of interest, you will go on to:

3. Appraise that evidence for both its applicability to your clinical case and for validity.

4. Taking patient wishes and preferences into account, integrate that evidence with your clinical expertise and apply it to the care of the patient.

5. Evaluate your performance with this patient.

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