Literature Review How to...

Critical Review

Extensive search and evaluation of the literature on a topic.

• Goes beyond description of the literature; includes some analysis.
• Search is performed until saturation is reached.
• Results in a hypothesis or model.
• Identifies areas of significance.
• Evaluates the literature according to contribution to the topic.
• Results are explained in chronological or conceptual order.
• Goals is to identify significant contributions that lead to a new theory.

Scoping Review

Assesses the size and scope of research literature on a topic.

• Seeks to identify the nature and estimate the scale of research evidence available on the topic.
• Search must be structured and clear.
• Literature includes both published and unpublished studies.
• Comprehensiveness of the search is determined by time and scope constraints.
• Can included original ongoing research studies.
• Can include handsearching and interviews of experts.
• Does not provide assessment of the quality of the studies found.
• Results can be a explained using combinations of charts/graphs and narrative.

Narrative Review        (also known as Traditional Literature Review)

Comprehensive review of a body of literature on a topic.

• Requires a focused research question.
• Literature includes information resources concerning existing theories and models.
• Literature includes original research studies (RCTs, Observational studies, qualitative studies and quantitative studies)
• Literature can include editorials by experts and opinion leaders.
• The search is formalized and structured.
• The search can include reference lists until saturation.
• Citing sources and documenting search strategies are growing in adoption.
• Results are presented in narrative that summarizes findings and draws conclusions, identifies gaps and inconsistencies.
• Weakness: resulting narrative is subject to bias.

Narrative Synthesis        (also known as Textual Narrative Synthesis)

Literature review targeting the highest quality evidence.

• All literature is considered, but the highest quality is given priority.
• Search is comprehensive using systematic search methods.
• Requires identification of quantitative and qualitative studies.
• Information sources are limited to evidential information only.
• Search strategies are explicit - clear and detailed.
• Grey literature may or may not be included.
• Results are explained in narrative as well as charts and graphs.

Integrative Review       (also known as Integrative Synthesis)

Review of the literature on a topic to capture a diverse range of studies on a topic to understand a phenomenon or healthcare problem.

• Literature retrieved consists of diverse types of research (experimental and non-experimental; qualitative and quantitative) and study methods (RCTs, Observational studies, Qualitative studies, etc.), hence the label integrative.
• Literature includes primary studies, research registries, reference lists, hand-searched journals, gray literature and interviews of experts.
• Have the potential to develop new theories, inform research, impact practice, and inform policy issues.
• Results are displayed in narrative as well as graphs, charts, and tables.

Mapping / Descriptive Reviews      (also known as an Evidence Map, Systematic Map, or Systematic Mapping Review)

Maps and categorizes literature visually to answer a question on the breadth of a topic.

• Identifies where literature is found on a topic and where gaps in the literature are located.
• Comprehensiveness is determined by the project scope: publication date range, publication type, geography, language, and other criteria.
• Search utilizes a range of databases.
• Search can include Cochrane Database of Systematic Reviews and PROSPERO.
• Literature includes published and unpublished studies, reviews, gray literature and ongoing research.
• Searches can include internet resources and specialist organizations.
• The literature itself is not analyzed critically.
• Results are displayed in graphs, charts, etc.
• Answers questions concerning structure, location, quantity and quality of the literature on a topic generally,
  • Analysis of the literature can be grouped by study design or other feature.
  • Analysis can indicate the need for additional primary or secondary research.

Umbrella Review         

An aggregation of review literature into one document.

• Focuses on research of one condition or problem with competing interventions.
• Targets reviews only; search for primary studies is unusual.
  • May include evidence syntheses and other study designs as appropriate.
  • May include 2-3 grey literature resources.
• Utilizes systematic search methods, and database systematic review filters, but comprehensiveness can vary.
• Reference lists and literature mapping may be used to uncover additional studies.
• Provides assessment of quality on individual reviews as well as all the reviews as a whole.
• Results are displayed in graphs and charts as well narrative.
• Goal
  • to identify what is known on the topic, then make practice recommendations
  • to identify what is NOT known, then make recommendations for future research.

Review of Reviews

An aggregation of systematic reviews only.

• Focuses on systematic reviews on one condition or problem with competing interventions.
• The systematic search strategy and search method strictly follows systematic review guidelines with explicit documentation.
• Database searching may utilize systematic review filters.
• May include searches for recent primary studies published since review study publications.
• May use CDSR, DARE, or PROSPERO.
• May include handsearching, reference lists, interviews of experts, and citation mapping.

Rapid Review:         (also known as Rapid Evidence Synthesis)

Uses systematic review methods to critically appraise what is already known about a topic within the time constraints of the reviewer (often less than 5 weeks.

• Explores a narrow research question, but comprehensiveness is determined by short deadlines.
• Search process can vary from fairly exhaustive to much simpler (omits stages of the systematic review search; less rigorous).
• Search limitations must be documented and explicit, noting inclusion and exclusion criteria.
• Quality assessment is limited by time constraints.
• Results are displayed in charts and graphs as well as narrative.
• Goal: to identify quantity and overall quality of the literature to the extent time will allow.

Systematic Review

An exhaustive, formal search of the literature seeking to answer a narrowly defined research question.

• Comprehensive, rigorous review of the literature following proscribed guidelines and standards (PRISMA, JBI, Cochrane, etc.) and for appraisal.
• Requires an exhaustive, complete search and appraisal including explicit documentation (clear and detailed).
• Handsearching, reference lists, and internet searching may or may not be included.
• Requires pre-set inclusion/exclusion criteria.
• Literature includes a wide range of publication types (RCTs, Observational studies, Case Reports, etc.).
• In-depth quality assessment is performed on included studies only.
• Results are explained in narrative with accompanying tables.
• Identifies what is known and what remains unknown.
• Offers recommendations for areas of future research.

Qualitative Systematic Review        (also known as Qualitative Evidence Synthesis)

• Search follows standard systematic review methods (PRISMA, Cochrane, JBI, etc.)
• Searches utilize multiple databases.
• Search strategy must be documented clearly and in detail.
• Included studies must follow recognized qualitative methods of data collection and data analysis.
• Literature may include theses and book chapters.
• May include reference lists, citation mapping, and repositories.

Meta Analysis Review

Summative review of literature where statistical results from individual research studies are combined using statistical normalization to provide a precise quantitative answer to a focused research question.

• Designed to be an exhaustive search of a wide range of literature.
• Search process is documented and explicit (clear and detailed), following an official protocol or guideline (PRISMA, JBI, Cochrane, etc.).
• Search sources can include handsearching, reference lists, and internet searching.
• Pre-set inclusion/exclusion criteria assist in quality assessment of individual studies.
• Statistical results are displayed graphically in charts, graphs, funnel plots, etc.
• Analysis of measures of effects assuming absence of heterogeneity is described and explained.

Mixed Method Review           (also known as Mixed Methods Synthesis)

Broad search of the literature that is methodologically inclusive.

• Review may be conducted utilizing three separate searches
  • Quantitative search filter search
  • Qualitative search filter search
  • Mix-methods search
  • Or may be conducted in one comprehensive search without study filters.
• Findings answer multiple research questions through the combination of 2 or more qualitatitive and quantitative studies within a single study (trials registers and theses, reference lists, interviews with experts, and gray literature, etc.).
• Results determine both the effect and appropriateness of interventions as well as identify gaps in knowledge.

Additional Literature Types

• State of the Art Review
• Cochrane Review of Effects
• Comparative Effectiveness Review
• Diagnostic Systematic Review
• Network Meta Analysis
• Prognostic Review
• Psychometric Review
• Review of Economic Evaluations
• Systematic Review of Epidemiology Studies
• Rapid Evidence Assessment
• Rapid Realist Synthesis
• Qualitative Evidence Synthesis
• Qualitative Meta Synthesis
• Qualitative Research Synthesis
• Best Fit Framework Synthesis
• Framework Synthesis
• Meta Aggregation
• Meta Ethnography
• Meta Interpretation
• Meta Narrative Review
• Meta Study
• Meta Summary
• Thematic Synthesis
• Bayesian Meta Analysis
• EPPI Centre Review
• Critical Interpretive Synthesis
• Realist Synthesis (Realist Review)
• Concept Synthesis (Concept analysis)
• Methodological Review