Evidence-Based Practice for Nurses

The Cochrane Library (2017) stated, “A systematic review attempts to iden-

tify, appraise and synthesize all the empirical evidence that meets prespecified

eligibility criteria to answer a given research question.” A systematic review of

the literature includes both a systematic approach to obtaining the literature

and a systematic approach to conducting the review of the literature after it

is obtained. “Researchers conducting systematic reviews use explicit methods

aimed at minimizing bias, in order to produce more reliable findings that can

be used to inform decision making” (Cochrane Library, 2017).

Understanding the critical steps to these processes assists in evaluating the

quality of a systematic review. The Cochrane Library offers specific guidelines

for conducting systematic reviews. There are three types of Cochrane systematic

reviews: (1) intervention reviews to assess the benefits and harms of interventions

used in health care and health policy, (2) diagnostic test accuracy reviews to

assess how well a diagnostic test performs in diagnosing and detecting a par-

ticular disease, and (3) methodology reviews to address issues relevant to how

systematic reviews and clinical trials are conducted and reported. The Cochrane

Handbook for Systematic Reviews of Interventions and the Cochrane Handbook

for Diagnostic Test Accuracy Reviews offer specific guidance for these reviews.

Before beginning the systematic review process, the author of the review

clarifies the problem and the questions to be answered (Cochrane Library,

2017; Cooper, 1998). Questions that can be answered by a systematic review

include: What is the state of the theoretical knowledge in this area? What are

the methodological gaps in the current studies? What is the impact of interven-

tions on patient outcomes from these studies? What should be the focus of the

next research study? and How are two bodies of literature related or unrelated?

Because the systematic review can assist in answering many types of questions,

the author must define what variables and/or concepts are important to the

problem or question. Furthermore, the author may also identify the relation-

ships between variables if these relationships are important to the problem

being investigated.

The author must decide what kinds of studies to include in the systematic

review. Therefore, inclusion and exclusion criteria must be established based

on the problem and question to be answered. For example, if the question

relates to a particular age group, then research reports that include only that

particular age group would be included in the systematic review. If studies

with a particular design are the target—for example, a randomized controlled

trial—then only reports with this design would be included. The inclusion and

exclusion criteria must logically flow from the problem and questions.

After the problem and question to be answered by the systematic review

are clarified and the inclusion and exclusion criteria are identified, the author

314 CHAPTER 12 Other Sources of Evidence