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A systematic review is an important process in nursing practice that involves writing a critical synthesis of the available literature in a methodical manner. A systematic review is conducted to identify, select, synthesize, and appraise high-quality studies relevant to a specific clinical question. High-quality studies must have a rigorous and explicit design allowing findings to be probed against research intentions and clear contexts. When conducting systematic reviews nurses and other health care professionals should be aware that there is a hierarchy of evidence. It is also important for nurses to understand that any empirical evidence should be derived from studies that involved designs that are both rigorous and explicit. However, there are differences between systematic and narrative reviews.
A systematic review is guided by a specific question while a narrative review is not necessarily guided by a question. The selection process in a systematic review is usually explicit and clear, while in a narrative review, the selection process is not described. Additionally, a peer review protocol is included in a systematic review while a narrative review has no protocol. The purpose of systematic reviews in nursing practice is to facilitate the use of best available research evidence in decision-making processes. In this article, the steps involved when writing a nursing systematic literature review are discussed.
Developing the Review Question
In the first step, a person conducting a systematic review should select a topic area. The process of selecting a topic can be influenced by different triggers such as medical problems encountered and contemporary issues. Nurses should choose a topic from topics related to their professional nursing practice background or specialization. One should identify an area of interest, a question, issues relating to the question, gains associated with the investigation of the question, rationale for asking the question, and gap in knowledge in the selected area.
The selected topic area should be narrowed to a specific focused and answerable review question. The importance of the question is to guide the systematic literature review. The question should be in PICO format and should contain the following variables: Population (P), intervention (I), comparative interventions (C) and the outcomes (O). The formulation of the review question is important because it supports all aspects of the review methodology. Every step of the systematic literature review is influenced by the review question. When conducting the systematic literature review one should consider how the question is related to the research design of the studies to be included in the review process. The main quantitative research designs include case-control studies, case reports and case series, randomized controlled trials, cohort studies, systematic reviews, and meta-analysis. The main qualitative research designs include ethnographic research design, phenomenological research design, and grounded theory research design.
Writing the Plan and Background to the Review
A plan helps to describe the review question and the rationale for the method to use to conduct a systematic review. When creating a plan for the systematic literature review, the researcher should include information relating to how studies will be retrieved, appraised, and synthesized. The methods of retrieving, appraising, and synthesizing studies should be described in advance to try and minimize bias. The method selected by the researcher to review the papers cannot be changed. For instance, if the researcher indicates in the plan that only randomized controlled trials (RCTs) will be reviewed; another type of study cannot be included.
Specifying Objectives, and Inclusion and Exclusion Criteria
This step of the systematic review involves clarifying problem statements, aims and objectives, and review questions. An example of a problem statement is: It is not known if the treatment approach1 or treatment approach 2 is more effective for treating adult patients with Chronic Obstructive Pulmonary Disease (COPD). An example of a review question is: Is treatment approach 1 or treatment approach 2 more effective for treating adult patients with COPD. The aim of the study can be derived from the problem statement. For instance, the aim of the study is: To investigate if there is a difference between treatment approach 1 or treatment approach 2 for adult patients with COPD.
At this stage, the researcher should explain the inclusion and exclusion criteria, sources of evidence, keywords, and the documentation of the search. The choice of relevant articles is based on sensitivity and specificity concepts. Sensitivity can be realized by ensuring that the total numbers of studies that meet the inclusion criteria are recorded. However, some studies are discarded later due to a lack of relevancy. Specificity can be realized by excluding non-relevant studies. The relevance of the selected studies can be determined by exploring the title, abstract, or full-text article.
Conducting a Comprehensive and Systematic Literature Search
The process of conducting a comprehensive and systematic literature review is to retrieve all studies that relate to the review question. The focus of the researcher in this stage is to search for relevant studies from different databases and internet search engines. The main objective of the search is to obtain a comprehensive list of both published and unpublished primary studies. It is important to use all the synonyms relating to the review question and combine them using Boolean operators ‘OR,’ ‘AND,’ and ‘NOT.’ The use of the Boolean operators helps to retrieve relevant studies relating to the review question.
Working with Primary Papers
The focus of this step is to select appropriate papers that meet predetermined selection criteria to answer the review question. This stage is conducted in two parts: The focus of the first part is sifting through the articles’ titles and abstracts, screening them and selecting those that meet the inclusion criteria. The second part involves reading the full text of every identified article to determine the one that meets the set inclusion criteria. The inclusion and exclusion criteria may involve the use of PICO components.
The researcher should appraise the quality of selected articles to assess how differences in quality might influence the study results. Appraisal involves the process of systematically and carefully examining studies to assess their value, trustworthiness, and relevance in relation to the review question. Among the aspects to explore when appraising a study are whether the title reflects the content, authors are credible, abstract involves a summary of key components, the aim of the research is clearly stated, ethical issues are identified and addressed, and the methodology is identified and justified. Other aspects to check relate to whether the discussion and conclusion are comprehensive.
The focus of data extraction is collecting findings from all relevant studies that meet the selection criteria. Relevant information that provides an answer to the review question is extracted from the selected article. Different data extraction tools, such as the Joanna Briggs Institute tools, can be used.
Synthesizing, Summarizing, and Presenting Findings
In this section, the researcher attempts to find the answer to the review question. In a quantitative review, all similar results, in regards to the designs, interventions, and outcomes, can be combined by conducting a statistical procedure, such as a meta-analysis. In a qualitative review, combined results of all the studies that are included can be synthesized under one theme or sub-themes. Syntheses can be done through charts, textual descriptions, by the grouping of similar data, transforming data into a common rubric, and translating data either by the content or thematic analysis.
The findings of the comprehensive search can be presented either in a table or textually. The researcher can write a narrative summary using structured headings. When using structured headings, the researcher should make sure that all the details relating to the intervention, population, or exposure and outcomes are included.
The summary of the findings extracted from the selected studies depends on the type of data that the researcher is handling. When synthesizing quantitative data, the summary can involve the use of either in a tabular, chart or graphical format. Qualitative data can be summarized by using themes and sub-themes.
Writing the Discussion Section and Completing the Review
It is important to start writing the discussion section by providing a summary of the review findings. The discussion of findings should be in the same order as they were presented in the previous section. The discussion should focus on comparing and contrasting study findings of the studies, discussing the results with respect to practice, and stating some overall conclusions about the study.
Systematic reviews are important processes in nursing practice because they facilitating the use of best available research evidence in decision-making processes. Professional nursing writers understand that when conducting systematic reviews, hierarchy of evidence is of utmost importance. Nurses and other health care professionals should follow the required steps when writing a nursing systematic literature review. The main steps involved in writing a systematic literature review are developing a review question, writing the plan and background to the review, specifying objectives and inclusion and exclusion criteria, and conducting a comprehensive and systematic literature search. Other steps include selecting, appraising, and extracting data; synthesizing, summarizing, and presenting findings; and writing the discussion and completing the review.