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Systematic Reviews

What does it take to do a systematic review?

Time: On average, systematic reviews require 18 months of preparation.

A teamA systematic review can't be done alone! You need to work with subject experts to clarify issues related to the topic: librarians to develop comprehensive search strategies and identify appropriate databases; reviewers to screen abstracts and read the full text; a statistician who can assist with data analysis; and a project leader to coordinate and write the final report.

A clearly defined question: Clarify the key question(s) of you systematic review and the rationale for each question. Use the PICO framework to identify key concepts or aspects of the question. Determine inclusion/exclusion criteria.

A written protocol: You need to write a protocol outlining the study methodology. The protocol should include the rationale for the systematic review, key questions broken into aspects or "PICO components", inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence for each key question. Need help writing a protocol? See the University of Warwick's protocol template.

A registered protocol: After you write the protocol, you should register it with PROSPERO, an International Prospective Register of Systematic Reviews. Registration is free and open to anyone undertaking systematic reviews of the effects of interventions and strategies to prevent, diagnose, treat, and monitor health conditions, for which there is a health related outcome.

Comprehensive literature searches: First, identify systematic reviews that may address your key questions. Then, identify appropriate databases and conduct comprehensive and detailed literature searches that can be documented and duplicated.

Citation management: You should have working knowledge of EndNote to help manage citations retrieved from literature searches.

Follow reporting guidelines: Use appropriate guidelines for reporting your review for publication.

For more information about the nuances of conducting systematic reviews, contact your Medical Information Specialist.

A review plan or protocol

A major cause of bias in a systematic review is answering a different question to that being originally asked. This is why it is important to develop a review plan or protocol.

The benefits of having a protocol before the beginning of a review:

  • relate to the validity and merit of a research process that reduces risk of bias
  • promotes a systematic rather than ad hoc approach to the review process
  • facilitates communication with others and promotes consistency between review team members
  • support the reliability and usefulness of reviews to health professionals

Steps for a protocol and conducting a systematic review

  1. Check existing reviews/protocols - a decision needs to be made whether to abort the review or amend the question.
  2. Formulate a specific question - PICO (for a quantitative review) - PICo (for a qualitative review)
  3. Inclusion criteria – puts the question into operation (population, intervention or comparison, outcome, study design, language, publication)
  4. Exclusion criteria for not including certain studies e.g. specific populations, language, setting
  5. Eligibility criteria for including studies– qualitative and quantitative (study design, language, date of publication, duplicate data)
  6. Search strategy - explicit and reproducible (must include grey literature)
  7. Critical appraisal - Assess risk of bias in individual studies
  8. Synthesis of results (interpret/analyse results/determining the applicability of results
  9. Report - comprehensive report on all steps of the systematic review and presents results

Tip: read the PRISMA statement!

PRISMA statement

Where to register your protocol?

Once you've developed your protocol, register it. This is a basic requirement for a trial or systematic review, to check if your study has already been done by someone else, and whether your proposed review is necessary.

Where to register your protocol: