Systematic reviews of quantitative studies often involve statistical integration of findings through meta-analysis, a procedure whose advantages include objectivity, enhanced power, and precision; meta-analysis is not appropriate, however, for broad questions or when there is substantial inconsistency of findings.

Chapter 29

Systematic Reviews of Research Evidence: Meta-Analysis,
Metasynthesis, and Mixed Studies Review

Question

Tell whether the following statement is true or false:

Evidence-based practice relies on rigorous integration of research evidence on a topic through systematic reviews.

Answer

True

Evidence-based practice relies on rigorous integration of research evidence on a topic through systematic reviews. A systematic review methodically integrates research evidence about a specific research question using carefully developed sampling and data collection procedures that are spelled out in advanced in a protocol.

Systematic Review

Integrates research evidence about research question
Carefully developed:
Sampling
Data collection procedures
Spelled out in advance in a protocol

Question

Tell whether the following statement is true or false:

Systematic reviews of qualitative studies often involve statistical integration of findings through meta-analysis.

Answer

False

Systematic reviews of quantitative studies often involve statistical integration of findings through meta-analysis, a procedure whose advantages include objectivity, enhanced power, and precision; meta-analysis is not appropriate, however, for broad questions or when there is substantial inconsistency of findings.

Meta-Analysis

Objectivity
Enhanced power
Precision
Not appropriate
Broad questions
Substantial inconsistency of findings

Criteria for Using Meta-Analytic Techniques in a Systematic Review

The research question being addressed or the hypothesis being tested across studies should be very similar, if not identical.
Concern regarding whether there is a sufficient base of knowledge for statistical integration
Consistency of evidence

Steps in a Meta-Analysis

Formulating the problem
Designing the meta-analysis study
Searching the literature for data
Evaluating study quality
Extracting and encoding data for analysis
Calculating effects
Analyzing the data
Writing a meta-analytic report

Question

Tell whether the following statement is true or false:

The steps in both quantitative and qualitative integration are similar.

Answer

True

The steps in both quantitative and qualitative integration are similar and involve formulating the problem, designing the study, searching the literature for a sample of primary studies, evaluating study quality, extracting and encoding data for analysis, analyzing the data, and reporting the findings.

Quantitative and Qualitative Research

Formulating the problem
Designing the study
Searching the literature for a sample of primary studies
Evaluating study quality
Extracting and encoding data for analysis
Analyzing the data
Reporting the findings

Question

Tell whether the following statement is true or false:

There is consensus on systematic reviews should include the grey literature.

Answer

False

There is no consensus on whether systematic reviews should include the grey literature—that is, unpublished reports.

Concerns

No consensus on whether systematic reviews should include the grey literature
Quantitative studies
Bias against the null hypothesis
Publication bias
Examined with funnel plot

Meta-Analysis

Effect size index: quantifies the magnitude and direction of relationship between variables
Two common effect size in nursing
Standardized mean difference
Odds ratio
Pooled to yield an estimate of the population effect size
Weighted average
Inverse variance

Statistical Heterogeneity

Fixed effects model: assumes a single true effect size
Random effects model: assumes a distribution of effects
Forest plot

Nonrandom Heterogeneity

Subgroup analyses
Meta regression
Purpose: identify clinical or methodologic features systematically related to variation in effects

Quality Assessments

Exclude weak studies from reviews
Differentially weight studies or sensitivity analyses: test whether including or excluding weaker studies changes conclusions

Question

Tell whether the following statement is true or false:

Metasyntheses are more than just summaries of prior quantitative findings; they involve a discovery of essential features of a body of findings and, typically, a transformation that yields new insights and interpretations.

Answer

False

Metasyntheses are more than just summaries of prior qualitative findings; they involve a discovery of essential features of a body of findings and, typically, a transformation that yields new insights and interpretations.

Undertaking Metasynthesis

“A family of methodologic approaches to developing new knowledge based on rigorous analysis of existing qualitative research findings”

Approaches

Meta-ethnography
Metastudy
Metasummary
Critical interpretive synthesis (CIS)
Grounded formal theory
Thematic synthesis

Metasynthesis Analysis

Analyzing and interpreting data

-Noblit and Hare approach

-Paterson and colleagues approach

-Sandelowski and Barroso approach

Paterson and Colleagues

Metadata analysis: the study of results in a specific substantive area through analysis of the processed data
Metamethod: the study of the studies’ methodologic rigor
Metatheory: the analysis of the theoretical underpinnings on which the studies are grounded

Sandelowski and Barroso

Summaries: descriptive synopses
Syntheses: interpretative explanations of the data

Metasummary

Developing a list of abstracted findings from the primary studies
Manifest effect sizes
Frequency effect size
Intensity effect size

Mixed Methods Research

Systematic mixed studies reviews
Systematic reviews
Disciplined
Auditable
Integrate and synthesize findings

Reporting Guidelines

PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) is useful for writing up a systematic review of RCTs.
MOOSE (Meta-analysis of Observational Studies in Epidemiology) guides reporting of meta-analyses of observational studies.

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