9.1 Conducting systematic literature reviews
3 min read•august 9, 2024
Systematic literature reviews are a crucial tool in nursing research. They involve a comprehensive analysis of all available research on a specific topic, following a structured protocol to minimize bias. This process ensures a thorough examination of existing evidence to inform clinical practice.
Planning, conducting, and analyzing are key steps in a . Researchers define criteria, develop a protocol, craft search strategies, and select appropriate sources. They then extract data, assess study quality, and synthesize findings to draw meaningful conclusions for nursing practice.
Planning the Review
Defining Systematic Review and Criteria
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- Systematic review involves comprehensive analysis of all available research on a specific topic
- Follows structured, predefined protocol to minimize bias and ensure reproducibility
- specify characteristics studies must meet to be included in review
- May include factors like publication date, study design, population, interventions
- outline reasons for rejecting studies from review
- Can include factors such as language restrictions, small sample sizes, poor methodological quality
- statement provides guidelines for conducting and reporting systematic reviews
- Consists of 27-item checklist and flow diagram to enhance transparency and completeness
Developing a Review Protocol
- Protocol outlines entire review process before it begins
- Includes , search strategy, inclusion/exclusion criteria, methods
- Helps prevent bias by establishing methods prior to knowing study results
- Can be registered with organizations like PROSPERO to increase transparency
- May undergo peer review to ensure quality and comprehensiveness
Conducting the Search
Crafting an Effective Search Strategy
- Search strategy involves developing comprehensive list of relevant search terms
- Includes keywords, subject headings, and synonyms related to research question
- May use controlled vocabulary (MeSH terms) for more precise searching
- Boolean operators (AND, OR, NOT) combine search terms to refine results
- AND narrows search (diabetes AND exercise)
- OR broadens search (heart attack OR myocardial infarction)
- NOT excludes terms (cancer NOT lung)
- Truncation () and wildcards (?) capture variations of terms (nurs for nurse, nursing, nurses)
Selecting Appropriate Information Sources
- Database selection crucial for comprehensive coverage of relevant literature
- Common databases include , , ,
- encompasses non-commercially published materials
- Includes conference proceedings, dissertations, government reports
- Helps reduce by including unpublished studies
- Hand-searching key journals and reference lists of included studies
- Contacting experts in the field for additional relevant studies or unpublished data
Analyzing the Results
Extracting and Organizing Data
- Data extraction involves systematically collecting relevant information from included studies
- Develop standardized form to ensure consistent data collection across all studies
- Extract key information such as:
- Study characteristics (authors, publication year, design)
- Participant demographics
- Interventions and comparators
- Outcome measures and results
- Potential sources of bias
- Use data management software (Excel, RevMan) to organize and store extracted data
- by two independent reviewers reduces errors and bias
Assessing Study Quality and Bias
- Quality assessment evaluates methodological rigor and potential for bias in included studies
- Various tools available depending on study design:
- for randomized controlled trials
- for observational studies
- for different study types
- Assess factors such as randomization, blinding, allocation concealment, attrition
- Consider how study quality impacts strength of evidence and conclusions drawn
- Use quality assessment results to conduct sensitivity analyses or subgroup analyses
- or combines results across studies to draw overall conclusions
Key Terms to Review (21)
CASP Checklists: CASP Checklists are tools developed by the Critical Appraisal Skills Programme that provide a systematic way to evaluate the trustworthiness, relevance, and results of published research. These checklists help researchers and practitioners assess the quality of evidence in various types of studies, including randomized controlled trials, cohort studies, and qualitative research, ensuring that their findings are based on sound methodologies.
CINAHL: CINAHL, or the Cumulative Index to Nursing and Allied Health Literature, is a comprehensive database that provides access to nursing and allied health literature. It serves as an essential tool for conducting systematic literature reviews by offering a wide range of peer-reviewed articles, books, and evidence-based resources relevant to the nursing field and related disciplines.
Cochrane Library: The Cochrane Library is a comprehensive online resource that contains high-quality systematic reviews and meta-analyses of healthcare interventions. It plays a crucial role in evidence-based practice, providing healthcare professionals with reliable information to make informed decisions about patient care and treatment options.
Cochrane Risk of Bias Tool: The Cochrane Risk of Bias Tool is a systematic method for assessing the risk of bias in randomized controlled trials (RCTs), focusing on various domains that can affect the credibility of study findings. This tool aids researchers in evaluating the quality of evidence in systematic reviews and informs decisions on the reliability of trial results. By identifying potential biases, it enhances transparency and rigor in research appraisal and synthesis.
Confidence Interval: A confidence interval is a statistical range, derived from sample data, that is likely to contain the true population parameter with a specified level of confidence, typically expressed as a percentage. It helps researchers understand the precision of their estimates and the uncertainty involved in sampling, providing valuable insights when evaluating the strength and reliability of evidence in research findings.
Data extraction: Data extraction is the process of retrieving relevant information from various sources, particularly during systematic literature reviews. It involves identifying, organizing, and recording key data points from selected studies to facilitate analysis and synthesis, ensuring that the review is comprehensive and accurate.
Double data extraction: Double data extraction is a method used in systematic literature reviews where two independent reviewers extract data from the same set of studies to enhance accuracy and minimize bias. This approach helps to ensure that the data collected is reliable and comprehensive, as discrepancies between the reviewers can be identified and resolved, leading to a more rigorous review process.
Effect Size: Effect size is a quantitative measure that reflects the magnitude of a phenomenon or the strength of a relationship between variables in research. It provides a way to understand how meaningful the results of a study are, beyond just statistical significance. By measuring effect size, researchers can compare the effectiveness of different interventions and make sense of the practical implications of their findings.
Exclusion criteria: Exclusion criteria refer to specific characteristics or conditions that disqualify individuals or studies from being included in a systematic literature review. This concept is crucial as it helps to narrow down the focus of research by ensuring that only relevant and appropriate studies are considered, thereby improving the overall quality and reliability of the review findings.
Grey literature: Grey literature refers to research outputs and documents that are not formally published through traditional channels, such as academic journals or books. This can include reports, theses, conference papers, and other types of content that may not undergo rigorous peer review but can provide valuable insights and data for systematic literature reviews.
Inclusion Criteria: Inclusion criteria are specific characteristics or conditions that a study participant must meet to be eligible for inclusion in a research study. These criteria help define the target population and ensure that the findings of the study are relevant and applicable to that specific group. By setting clear inclusion criteria, researchers can reduce variability among participants, which enhances the reliability and validity of the study results.
Meta-analysis: Meta-analysis is a statistical technique used to combine and analyze data from multiple studies in order to derive a more precise estimate of effects or outcomes. It enhances the overall strength of evidence by synthesizing findings across various research, which can help inform practice and policy decisions.
Narrative synthesis: Narrative synthesis is a method used to integrate and summarize findings from multiple studies in a systematic way, often focusing on qualitative data to provide a coherent and comprehensive overview. This approach allows researchers to present a collective understanding of research outcomes and identify patterns or themes without relying solely on statistical techniques. It emphasizes the importance of context and the richness of the information gathered from different sources.
Newcastle-Ottawa Scale: The Newcastle-Ottawa Scale (NOS) is a tool used for assessing the quality of non-randomized studies, particularly cohort and case-control studies, in systematic reviews. It evaluates studies based on three main criteria: selection of study groups, comparability of groups, and the assessment of outcomes or exposure. This scale helps researchers determine the risk of bias in studies included in systematic reviews, ensuring that conclusions drawn from the evidence are reliable and valid.
PRISMA: PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. It is an evidence-based set of guidelines designed to help researchers improve the reporting of systematic reviews and meta-analyses, ensuring that these studies are conducted transparently and comprehensively. By following the PRISMA guidelines, researchers can enhance the clarity and reproducibility of their reviews, thus supporting high-quality evidence synthesis in various fields.
Publication bias: Publication bias occurs when the likelihood of research findings being published is influenced by the nature and direction of the results. This often leads to a disproportionate representation of positive or significant findings in the literature, while studies with negative or inconclusive results may remain unpublished. Such bias can distort the overall understanding of a topic, impacting systematic reviews, synthesis of findings, statistical analyses, and the integrity of published research in nursing and other fields.
PubMed: PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. It serves as a crucial tool for healthcare professionals and researchers in locating scientific literature, especially when conducting systematic literature reviews that require comprehensive and relevant studies.
Research Question: A research question is a clear, focused, and concise inquiry that guides a research study, helping to define the purpose and scope of the investigation. It serves as the foundation for the research process, allowing researchers to identify relevant literature, design appropriate methodologies, and analyze data effectively. Formulating a strong research question is essential for driving the entire study and ensuring meaningful results.
Risk of bias: Risk of bias refers to the potential for systematic errors in the design, conduct, or reporting of research that can lead to misleading results or conclusions. It is crucial to identify and minimize risk of bias when conducting systematic literature reviews, as it affects the validity and reliability of the findings being synthesized. By addressing risk of bias, researchers can enhance the quality and credibility of their review outcomes.
Systematic review: A systematic review is a structured and comprehensive synthesis of research studies that aim to answer a specific research question by systematically searching, evaluating, and summarizing all relevant studies on a given topic. This method helps in assessing the strength of evidence by minimizing bias and providing clear conclusions based on the aggregate findings of multiple studies.
Web of Science: Web of Science is a comprehensive research database that provides access to a wide range of scholarly articles, conference proceedings, and other academic resources. It is widely used by researchers to conduct systematic literature reviews as it enables them to efficiently search for relevant literature, analyze citation patterns, and track the impact of research across various disciplines.