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Systematic Reviews - Research Guide

Overview

Overview of systematic reviews

A systematic review analyses evidence from the literature in order to answer a specific research question.

It begins with the researcher formulating a question or hypothesis without knowing the conclusion.
The systematic review:

  • describes the search process
  • presents all evidence and/or data sourced from the search (including positive and negative results)
  • is transparent in that its search and analysis methods can be replicated to achieve the same results
  • is structured as an experimental report
  • has an abstract
  • offers an answer.

Source: Davina French, 2018

 

The Cochrane Collaboration is an important research organisation that provides support and guidance for researchers undertaking systematic reviews. The Cochrane Handbook for Systematic Reviews of Interventions (Section 1.2) defines a systematic review as follows:

A systematic review attempts to identify, appraise and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question. Researchers conducting systematic reviews use explicit methods aimed at minimizing bias, in order to produce more reliable findings that can be used to inform decision making.

 

A quantitative systematic review includes studies that have numerical data.
A qualitative systematic review includes data from observations, diaries, interviews, or other verbal interactions and focusses on the interpretation of, and significance given to, the data collected by the participants.

Conducting a systematic review will require you to follow this process:

  1. Start a systematic review

  • Check existing reviews/protocols - ensure the proposed study is unique.    

  

  2. Develop your clinical question

  • Develop a specific question so your search will be relevant - use PICO or PICo.
  • Devise a protocol - determine the inclusion/exclusion and eligibility criteria for further studies.

  

  3. Source the literature

  • Conduct a comprehensive search - your search strategy must be explicit and reproducible.

  

  4. Appraise your results

  • Select studies against eligibility criteria - follow your protocol.
  • Appraise studies - assess risk of bias in each study.
  • Extract relevant data for analysis.

  

  5. Document your review

  • Document the search process.
  • Prepare a comprehensive report on all of the steps of your systematic review and present results.   

Scoping review

Assesses emerging evidence and determines the scope of literature on a given topic. A scoping review should clearly indicate the volume of literature and studies available, as well as an overview of the review topic. Scoping reviews are useful for examining emerging evidence when it is unclear what specific clinical questions could be posed and addressed by a systematic review.

For more information on conducting a scoping review, see the following:

 

Umbrella review

Compares and contrasts the findings of previous reviews relevant to a review question.  An umbrella review synthesises only the highest level of evidence produced by other systematic reviews and meta-analyses.

 

Rapid review

Speeds up the systematic review process by omitting some stages of the systematic review. While less rigorous, rapid reviews provide more timely information for clinical decision-making compared with standard systematic reviews.

 

More information on review typologies

Literature or narrative review

Abdel-Moneim, A. S. (2014). Middle East respiratory syndrome coronavirus (MERS-CoV): Evidence and speculations. Archives of Virology, 159(7), 1575-1584. doi:10.1007/s00705-014-1995-5

Systematic review

Davlin, S.L., & VonVille, H.M. (2012). Canine rabies vaccination and domestic dog population characteristics in the developing world: A systematic review. Vaccine, 30(24), 3492-3502. doi:10.1016/j.vaccine.2012.03.069

Halton, K., Sarna, M.,Barnett, A., Leonardo, L., & Graves, N. (2013). A systematic review of community based interventions for emerging zoonotic infectious diseases in South East Asia. JBI Database of Systematic Reviews and Implementation Reports, 11(2), 1-235.

Cochrane review

Yamato, T. P., Maher, C. G., Saragiotto, B. T., Hancock, M. J., Ostelo, R. W. J. G., Cabral, C. N. M., ... Costa, L. O. P. (2015) Pilates for low back pain. Cochrane Database of Systematic Reviews.  doi:10.1002/14651858.CD010265.pub2

Systematic review protocol

Downes, M. J., Dean, R. & Bath-Hextall, F. J. (2013). Animal-assisted therapy for people with serious mental illness. The Cochrane Library.  doi: 10.1002/14651858.CD010818 

Review article

>Duclos, C., Beauregard, M.-P., Bottari, C. Ouillet, M.-C., & Gosselin, N. (2015).  The impact of poor sleep on cognition and activities of daily living after traumatic brain injury: A review. Australian Occupational Therapy Journal. 62(1), 2-12. doi: 10.1111/1440-1630.12164

Systematic review Literature (or narrative) review

A clearly defined topic or question is examined.

An overview of a topic is provided.

An explicit search plan or protocol is used to minimise bias.

An explicit search protocol or plan is not used.

A comprehensive search is undertaken to identify all potentially relevant studies.

The search process may or may not include all potentially relevant studies.

An explicit, predetermined protocol that specifies inclusion and exclusion criteria is used to select studies for the review.

An explicit, predetermined protocol is not used to select the studies that support the reviewer's recommendations.

The quality of individual studies is rigorously appraised in a meta-analysis, and a systematic synthesis of the results of included studies is undertaken with evidence "grades" applied to individual studies.

A level of evidence rating system may be used to "grade" the quality and strength of individual studies.

Evidence (research) is provided.

The review may be evidence-based but does not constitute evidence (research).

Authors usually recommend further research when evidence is lacking.

When evidence is lacking, authors make recommendations based on their opinions and experience.

A literature review can involve a systematic approach without being a full systematic review - see the Systematic Literature Review page of the Literature Reviews Research Guide. The Literature Reviews Research Guide provides more information on conducting a literature review.