Narrative Synthesis in Systematic Reviews

1
Narrative Synthesis in Systematic Reviews

• An ESRC Research Methods Programme project
• Mark Rodgers
• Lisa Arai, Nicky Britten, Mark Petticrew, Jennie
  Popay, Helen Roberts, Amanda Sowden

2
Structure of the Presentation

• What is narrative synthesis?
• Where does narrative synthesis (NS) fit in a
  systematic review?
• Why do we need guidance?
• Developing a framework for NS
• Building on the framework

3
What Is a Narrative Synthesis?

• NS are findings summarised and explained in words
• As used here, NS refers to the approach adopted
  to bringing together the findings from studies
  included in a systematic review
• No clear definition of NS
• Not a meta-analysis
• Can be alternative or complementary to MA

4
Where does it fit?

• Typical systematic review process
• Define review question
• Literature search
• Study selection
• Data extraction
• Study appraisal
• Synthesis
• Conclusions/recommendations

5
Why Do We Need Guidance?

• NS lacks transparency
• NS lacks reproducibility
• Variations in practice
• No coherent guidance currently exists

6
Developing guidance for NS

• Difficult (impossible?) to produce prescriptive
  guidance on the conduct of NS
• Most appropriate approach depends on context
• A NS toolkit may be better than traditional
  guidance
• Requires a structure

7
A framework for NS

• An descriptive framework of the NS process
• Developing a theory
• Developing a preliminary synthesis
• Exploring relationships in the data
• Assessing the robustness of the synthesis

8
Developing a theory

• Theory of change linking resources, activities,
  intermediate outcomes and ultimate goals
• How the intervention works, why and for whom
• Has implications for review question and
  inclusion criteria as well as interpretation
• Consider early in the review process
• Can be presented in narrative and/or diagrammatic
  form

9
Developing a preliminary synthesis

• Initial description of the results of included
  studies
• Organise results to describe patterns, e.g. in
• size/direction of effects
• factors/processes impacting on implementation
• quality
• Product of this process is preliminary and should
  be interrogated further

10
Exploring relationships in the data

• Explore relationships
• Between study characteristics and their findings
• Between the findings of different studies
• Explore influence of heterogeneity
• Variations in outcomes, methods, populations,
  interventions, settings etc
• Theory may help develop plausible explanations
  for observed differences
• Investigation of context partly dependent upon
  reporting of included studies

11
Assessing the robustness of the synthesis

• Robustness of NS depends on two related elements
• Methodological quality of included studies
• Trustworthiness of the synthesis product
• Availability of key information in primary
  studies
• Overall assessment of the strength of evidence
  available to support conclusions

12
Building on the framework (1)

• Populated framework with range of tools and
  techniques (e.g. tabulation, idea
  webbing/conceptual mapping, transforming and
  translating data)
• Allow reviewer to select tools/techniques most
  appropriate to the data being synthesised
• Not necessarily linear or sequential process
  reviewers will move iteratively between elements

13
Building on the framework (2)

• Conducted two test NS of domestic smoke alarm
  promotion interventions one effects, one
  implementation
• Qualified success - the approach can be further
  developed and refined
• Would benefit from application to a wider range
  of syntheses
• http//www.lancs.ac.uk/fass/projects/nssr/