PRISMA stands for Preferred Reporting Items for Systematic Reviews and Meta-Analyses. It is an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses.

An informative article in BMJ, 2021, The Prisma 2020 Statement: an updated guideline for reporting systematic reviews can assist in understanding PRISMA.

The aim of the PRISMA Statement is to help authors improve the reporting of systematic reviews and meta-analyses. We have focused on randomized trials, but PRISMA can also be used as a basis for reporting systematic reviews of other types of research, particularly evaluations of interventions. PRISMA may also be useful for critical appraisal of published systematic reviews, although it is not a quality assessment instrument to gauge the quality of a systematic review. The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram."

"The PRISMA 2020 explanation and elaboration: updated guidance and exemplars for reporting systematic reviews  explains and illustrates the principles underlying the PRISMA Statement. It is strongly recommended that it be used in conjunction with the PRISMA Statement.

PRISMA is part of a broader effort, to improve the reporting of different types of health research, and in turn to improve the quality of research used in decision-making in healthcare."

Step 1: Preparation To complete the the PRISMA diagram print out a copy of the diagram to use alongside your searches. It can be downloaded from PRISMA. You will need to print a copy for your totals, but you may want to print out a copy for each database you search as well. If you are using this system for a more advanced assignment, ask your supervisor whether they would like you to follow this system, or to specify totals for each individual database in your final PRISMA diagram.

Step 2: Doing the database search For each database enter each key search term individually. This should include ALL your search terms, including MeSH or CINAHL headings, truncation (like hemipleg*) and wildcard (like sul?ur) search terms. Combine all the search terms in the different combinations using boolean operators like AND or OR as appropriate. Apply all your limits (such as years of search, English language only, and so on). Once all search terms have been combined and you have applied all relevant limits, you should have a number of records or articles. Enter this in the top left box of the PRISMA flow chart for each database. If you have searched databases individually, add all the 'records identified' up and fill this total number in the PRISMA flow diagram which you will use for your coursework. Remember this process of adding up the number of records in individual database searches to a total  will need to be repeated at each step if you search databases separately.

Step 3: Additional sources If you have identified articles through other sources than databases (like manual searches through reference lists of articles you have found or Search engines like Google Scholar), enter the total number of records in the box on the top right of the flow diagram.

Step 4: Remove all duplicates To avoid reviewing duplicate articles, you need to remove any articles that appear more than once. You will need to go through all the records or articles you have found in the database and manually remove any duplicates. This is not easy to do if you have a large number of articles at this point. In this case you may want to export the entire list of articles to RefWorks (including citation and abstract) and remove the duplicates there. Enter the number of records left after you have removed the duplicate in the second box from the top.

Step 5: Screening articles The next step is to add in the number of articles that you have screened. This is the same number as you have entered in the duplicates removed box.

Step 6: Screening - Excluded articles You will now need to screen the titles and abstracts for articles which are relevant to your research question. Any articles that appear to help you provide an answer to your research question should be included. Record the number of articles excluded based on this screening process in the appropriate box (next to the total number of screened records) with a short reason for excluding these articles.

Step 7: Eligibility Subtract the number of excluded articles following the screening phase (step 6) from the total number of records screened (step 5) and enter this number in the box titled "Full-text articles assessed for eligibility". Get the full text for these articles to review for eligibility. 

Step 8: Eligibility - Records excluded Review all full-text articles for eligibility to be included in the final review. Remember you should be left with 6-8 papers at this point. Take a note of the number of articles that you exclude at this point and enter this number in the correct box titled: Full text articles excluded and write in a short reason for excluding the articles (this may be the same reason used for the screening phase).

Step 9: Included The final step is to subtract the number of excluded articles or records during the eligibility review of full-texts (step 8) from the total number of articles reviewed for eligibility (step 7). Enter this number in the final box. You have now completed your PRISMA flow diagram which you can now include in the results section of your assignment.

Adapted from GCU https://edshare.gcu.ac.uk/9113/2/PRISMA-2009-Flow-Diagram%20final%20%284%29.pdf