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Understanding the PRISMA Method

· 6 min read
Ahmed BARGADY
Ahmed BARGADY
PhD Student
What is PRISMA?

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. While it primarily focuses on reviews evaluating randomized trials, it enables transparent and complete reporting for diverse types of research.

As a PhD student, your "State of the Art" (SOTA) is not just a summary of what you read; it is a scientific study in itself. PRISMA ensures your SOTA is transparent, reproducible, and unbiased.

Why Your Supervisor Wants You to Use It​

  1. Reproducibility: If another researcher uses your search keywords and criteria, they should find the exact same set of papers.
  2. Bias Reduction: It prevents "cherry-picking" only the papers that support your hypothesis.
  3. Quality Control: It forces you to evaluate the quality of the papers you include.

The PRISMA Flow Diagram (2020)​

The most recognizable part of PRISMA is the flow diagram. This charts the lifecycle of a paper from your initial search to the final selection.

The 4 Phases of the Flow​

  1. Identification: You search databases (IEEE, PubMed, Scopus). You note down the exact number of results.
  2. Screening:
    • Deduplication: Removing the same paper found in multiple databases.
    • Title/Abstract Screening: Quickly rejecting irrelevant papers (e.g., wrong topic).
  3. Eligibility: You read the full text of remaining papers. You exclude papers that don't meet specific criteria (e.g., "Not written in English" or "Review articles only").
  4. Included: The final set of papers you will analyze in your thesis.
PhD Pro-Tip

Start a spreadsheet or use a tool (like Zotero or Excel) TODAY. You need to track the numbers as you go. Trying to reconstruct "how many papers I rejected based on title" three months later is a nightmare.

The PRISMA Checklist (Simplified)​

While the flow diagram is visual, the Checklist is structural. It consists of 27 items you must include in your report.

Section 1: Introduction​

  • Rationale: Describe the explicit question you are trying to answer. Why does this review need to be done?
  • Objectives: Provide an explicit statement of questions being addressed with reference to participants, interventions, comparisons, outcomes, and study design (PICO).

Section 2: Methods (Crucial for reproducibility)​

You must document exactly how you searched.

ItemRequirement
Eligibility CriteriaSpecify study characteristics (e.g., PICO, length of follow-up) and report characteristics (e.g., years considered, language).
Information SourcesDescribe all information sources (e.g., databases with dates of coverage, contact with study authors) in the search and date last searched.
Search StrategyPresent full electronic search strategy for at least one database, including any limits used, such that it could be repeated.
Selection ProcessState the process for selecting studies (i.e., screening, eligibility, included in systematic review).
Do not hide your query

You must include the exact Boolean string you used.

Bad: "I searched for AI and Healthcare."

Good: "("Artificial Intelligence" OR "Machine Learning") AND ("Healthcare" OR "Clinical") limited to years 2018-2024."

Section 3: Results​

  • Study Selection: Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.
  • Study Characteristics: For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.

Section 4: Discussion​

  • Summary of Evidence: Summarize the main findings including the strength of evidence for each main outcome.
  • Limitations: Discuss limitations at study and outcome level (e.g., risk of bias), and at review-level (e.g., incomplete retrieval of identified research).

Step-by-Step Implementation for your PhD​

Step 1: Define your Protocol​

Before searching, define your Inclusion and Exclusion criteria.

  • Inclusion: "Papers published between 2015-2025," "Empirical studies," "English language."
  • Exclusion: "Opinion pieces," "White papers," "Technical reports without validation."

Step 2: The Search (Identification)​

Run your query in Scopus, Web of Science, Google Scholar, etc. Export all results as .bib or .ris files.

Step 3: Deduplication​

Import all .bib files into a reference manager (Zotero, Mendeley, or EndNote). Use their "Find Duplicates" feature. Record the number of duplicates removed.

Step 4: Screening (The Fast Pass)​

Read only Titles and Abstracts.

  • Is it relevant? -> Keep.
  • Is it irrelevant? -> Delete.

Record the number of rejections.

Step 5: Eligibility (The Deep Dive)​

Download the full PDFs of the survivors. Read them.

  • Does this actually fit my criteria?
  • If you reject it here, you must note the specific reason (e.g., "Paper turned out to be a review, not an experiment").

Step 6: Synthesis​

The remaining papers constitute your "State of the Art."

note

You don't have to do this manually in Excel.

  • Rayyan: The industry standard for screening. You upload your references, and you can quickly press "Include" or "Exclude" (via keyboard shortcuts) based on abstract. It tracks the PRISMA numbers for you.
  • Covidence: Excellent for Cochrane-style reviews (paid, but check if your university has a license).
  • Parsifal: A free tool specifically for software engineering systematic reviews.

Conclusion​

PRISMA makes your thesis defensible. When your jury asks, "Why didn't you include the paper by Dr. Smith?", you can look at your PRISMA diagram and say:

"I identified it during the search, but it was excluded during the eligibility phase because it did not meet the criterion of having empirical validation."

That is the power of a systematic review.