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Systematic Reviews

Problem Formulation

Developing your protocol (i.e. research plan) involves:

  • developing the research questions
  • developing eligibility criteria (inclusion / exclusion criteria)
  • developing a coding manul for data extraction
  • determining how to manage the data (e.g. Endnote, RefWorks)

Research Question

Developing a research question for a systematic review requires an understanding of the existing literature, including gaps and uncertainties, definitions, and terminologies
Questions often use the PICO(S) framework:
  • Population/Participants
  • Interventions
  • Comparisons
  • Outcomes
  • Study design
PICO(s) statement:
To assess the effects of [intervention] compared to [comparison/control]  for [condition/problem] in [population] in [context] on [outcomes].
 
 
Examples of PICO(s):

In post-cardiac arrest patients with return of spontaneous circulation (P), does therapeutic hypothermia (I) compared with usual care (C), improve morbidity or mortality (O)? 

 

Eligibility Criteria

Study selection criteria determines which studies will be included in the systematic review.

Also called:

  • eligibility criteria
  • inclusion / exclusion criteria
Study eligibility criteria:
  • Clearly defines which subjects or studies will be included in the review
  • Essential for determining relevant and irrelevant studies
  • Determined by the research question
  • MUST be defined before data collection (i.e. conducting the search)

Resources Discussing Inclusion/Exclusion Criteria:

Study Eligibility Criteria is a workshop developed by the Agency for Healthcare Research and Quality (AHRQ) and provides an overview of eligibility criteria for systematic reviews.

Meline, T. (2006). Selecting studies for systematic review: Inclusion and exclusion criteria. Contemporary Issues in Communication Science and Disorders, 33(21-27).

Bibliographic Data Management

Use bibliographic management software to:

  • Maintain a searchable database of references related to the systematic review
  • Store all references selected for the systematic review
  • Keep track of number of references from each database
  • Determine number of duplicate references
  • Store all discarded references
  • Create citations and bibliography when writing up the results of the SR
Determine at the beginning of the research planning, what bibliographic management software you will use to manage and track data (i.e. references, citations)
  • Endnote ($)
    • UofC Library supports
  • Refworks (free)
    • UofC Library supports
  • Mendeley (free)
    • UofC Library supports
  • Others

 

Library workshops for bibliographic management software.

 

Lorenzetti, D. L., & Ghali, W. A. (2013). Reference management software for systematic reviews and meta-analyses: an exploration of usage and usability. BMC medical research methodology, 13(1), 141.

Documenting the Systematic Review

PRISMA - Preferred Reporting Items for Systematic Reviews and Meta-Analyses

A systematic review requires transparency and rigourness with the methodology.  It is therefore essential to document  the process from the beginning of the project.  PRISMA is one way of doing this.

  • It is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.
  • The aim of the PRISMA Statement is to help authors improve the reporting of systematic reviews.
  • The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram.
    • Use the PRISMA flow diagram to document your systematic review process
    • Use the 27-item checklist as a guide throughout the systematic review process

Cochrane Handbook - Documenting and Reporting the Search Process
(go to section 6.6.1)

"The search process needs to be documented in enough detail throughout the process to ensure that it can be reported correctly in the review, to the extent that ll the searches of all the databases are reproducible" (Cochrane Handbook, 2008, p. 144)

Coding System

Data extraction

A coding system to extract data (i.e. study details) from each study needs to be developed prior to collecting data (i.e. searching)

Standardized data extraction provides consistency, thereby potentially reducing bias, improving validity and reliability
  • Ensures that the same information is obtained (extracted) from each study
  • Identifies key components of the research including interventions, subjects, and methods
  • Should be developed early in the project
  • Pilot the data extraction form with a sample of studies
  • Keep track of revisions, corrections, amendments
  • If possible, pilot the exporting, analysis, and outputs of the data extraction form

 

Data Extraction Resources

Software for data extraction
Elamin, Mohamed B, et al. "Choice of data extraction tools for systematic reviews depends on resources and review complexity." Journal of clinical epidemiology 62.5 (2009):506-510. This article reviews different data extraction tools and offers advice on which tool to use to extract data.

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