PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
It is a set of guidelines for reporting systematic reviews and meta-analyses in the field of healthcare and medical sciences. The PRISMA statement provides a structured framework that assists researchers and authors in openly and thoroughly describing their research methods, findings, and results. PRISMA's primary aim is to enhance the quality reproducibility and transparency of systematic reviews and meta-analyses, ultimately improving the credibility and usability of research findings.
PRISMA uses a flow diagram to visualise the process of selecting and including studies in a systematic review or meta-analysis. It provides a clear picture of how studies are identified, screened, assessed for eligibility, and ultimately included or excluded at each stage of the review process.
Multiple other guidelines have been developed for example PRISMA-S for searching and PRISMA Extensions for abstracts, harms, protocols and scoping reviews.
PRISMA guidelines provide a clear structure for reporting research accurately, which helps researchers share unbiased and complete information with decision makers. Following PRISMA shows that the whole review process is transparent and trustworthy, which builds a strong base for making well-informed choices in various areas.
Before using PRISMA, read the official PRISMA statement and familiarise yourself with the PRISMA flow diagram. This will help you understand the guidelines and what you need to include in your report.
Clearly defining your research question and objectives is an essential step. Start with writing a protocol outlining the methods you'll use for searching, selecting, and analysing studies. This will help in maintaining transparency and reducing bias in your review. It is very important to finalise your search strategy before filling in the flow diagram, since even minor changes to the keywords can yield different results forcing you to start over.
This is the step in which you will start filling in your PRISMA flow diagram. Make sure you take notes of result numbers after each database search. Search for relevant studies using well-defined search strategies across multiple databases. Screen and select studies based on predetermined inclusion and exclusion criteria. Document your decisions and reasons for excluding studies.
Create a PRISMA flow diagram that depicts the flow of studies through the different phases of your review (e.g., identification, screening, eligibility, inclusion).
The flow diagram registers the initial number of studies identified through database and registers searches, as well as websites, organisations and other resources. It also tracks how many of these results were removed prior to screening, either due to deduplication or other reasons. After the initial screening, done by reviewing abstracts and titles, some records can be excluded, and the corresponding number must be included in the diagram.
Following the initial screening, authors need to retrieve full-text publications for further review. There might be cases where it's not possible to retrieve all records; in such instances, PRISMA guidelines require noting the number of records that couldn't be retrieved.
The remaining records undergo an assessment for eligibility. During this stage, the author should document the number of excluded records along with the reasons for exclusion. The last step of this process is to provide a final number of studies that will be included in the review.
Systematically extract relevant data from selected studies. This includes information about study characteristics, methodology, participants, interventions, outcomes, and results.
Evaluate the quality and risk of bias in the included studies. This step involves assessing factors such as study design, sample size, randomisation, blinding, and other relevant aspects e.g. Cochrane Risk of Bias tool.
More on quality and risk assessment tools.
Analyse and synthesise the data from the selected studies. This could involve qualitative synthesis, quantitative synthesis (meta-analysis), or a combination of both, depending on the nature of the studies and data.
Follow the PRISMA checklist and flow diagram to organise your report. PRISMA checklist includes 27 items targeting essential parts of the systematic review report, such as the introduction, methodology, results and discussion.
Interpret the findings of the included studies, discuss their implications, and highlight any limitations. Emphasise the implications for practice, policy, and further research.
When submitting your systematic review or meta-analysis for publication, make sure to adhere to the PRISMA guidelines in the preparation of your manuscript. Include the PRISMA flow diagram and checklist in your submission.
Compiled by:
Agata Scicluna Derkowska - Senior Assistant Librarian, University of Malta.
Emanuel Schembri - Visiting lecturer at the Department of Physiotherapy, Faculty of Health Sciences, University of Malta.
Last updated: 17 Nov, 2023
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. (2021a). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. Journal of Clinical Epidemiology; J Clin Epidemiol, 134, 178-189. https://doi.org/10.1016/j.jclinepi.2021.03.001
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. (2021b). PRISMA 2020 explanation and elaboration: updated guidance and exemplars for reporting systematic reviews. BMJ (Online); BMJ, 372, n160. https://doi.org/10.1136/bmj.n160