What is a systematic review?
A systematic review attempts to gather all the empirical evidence that fits pre-specified eligibility criteria to answer a specific research question.
It uses explicit, systematic methods that are selected with a view to minimizing bias, thus providing more reliable findings from which conclusions can be drawn and decisions made.
The key characteristics of a systematic review are:
- a clearly stated set of objectives with pre-defined eligibility criteria for studies
- an explicit, reproducible methodology
- a systematic search that attempts to identify all studies that would meet the eligibility criteria
- an assessment of the validity of the findings of the included studies, for example through the assessment of risk of bias
- a systematic presentation, and synthesis, of the characteristics and findings of the included studies
Sources
- Higgins, J.P.T., Thomas, J., Chandler, J., Cumpston, M., Li, T., Page, M. J., & Welch, V. A. (Eds.). (2023). Cochrane Handbook for Systematic Reviews of Interventions, version 6.4. https://www.training.cochrane.org/handbook.
- Page, M. J., McKenzie, J. E., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., … Moher, D. (2021). The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ (Online), 372, n71–n71. https://www.bmj.com/content/372/bmj.n71
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Page, M. J., Moher, D., Bossuyt, P. M., Boutron, I., Hoffmann, T. C., Mulrow, C. D., Shamseer, L., Tetzlaff, J. M., Akl, E. A., Brennan, S. E., Chou, R., Glanville, J., Grimshaw, J. M., Hróbjartsson, A., Lalu, M. M., Li, T., Loder, E. W., Mayo-Wilson, E., McDonald, S., … McKenzie, J. E. (2021). PRISMA 2020 explanation and elaboration: updated guidance and exemplars for reporting systematic reviews. BMJ (Online), 372, n160–n160. https://doi.org/10.1136/bmj.n160
Steps of a systematic review
Researchers conducting a systematic review need to follow various predetermined yet flexible and iterative stages that describe necessary steps required to produce a rigorous synthesis of the literature.
Steps include:
- Planning a systematic review
- Identifying studies and sources
- Evaluating and appraising results
- Collecting and combining data
- Explaining the synthesis
- Summarizing the findings
Acknowledgement: This guide is based on the PIECES acronym developed by M. J. Foster and S. T. Jewell in their book Assembling the PIECES of a systematic review: A guide for librarians (Rowman & Littlefield, 2017).