Scoping Review vs Systematic Review: When to Choose What (And How to Write Both)

Review articles are among the most cited publication types in medical literature. But when you decide to write one, the first question is: should it be a systematic review or a scoping review? Many researchers default to systematic reviews without considering whether a scoping review might be more appropriate — and often easier to execute.

This guide explains the key differences, helps you decide which type suits your research question, and walks through the methodology for both.

Key Differences Between Scoping and Systematic Reviews

While both are structured, evidence-based reviews, they serve different purposes:

Systematic Review:

• Answers a specific, focused clinical question (e.g., "Does Drug X reduce mortality in condition Y?")
• Uses strict inclusion/exclusion criteria
• Assesses quality of included studies (risk of bias)
• May include meta-analysis (pooling numerical data)
• Follows PRISMA guidelines
• Requires protocol registration (PROSPERO)
• Typically takes 6-12 months

Scoping Review:

• Maps the breadth of literature on a broader topic (e.g., "What research exists on telemedicine in rural India?")
• Uses broader, more inclusive criteria
• Does not formally assess study quality (though some do)
• Does not include meta-analysis
• Follows PRISMA-ScR (PRISMA extension for Scoping Reviews)
• Protocol registration recommended but not always required
• Typically takes 3-6 months

When a Scoping Review Is the Better Choice

Scoping reviews are particularly valuable in these situations:

• Emerging topics: When a field is new and you want to map what research exists before conducting a focused systematic review. Example: "AI applications in radiology diagnosis in India."
• Broad, complex questions: When the topic spans multiple disciplines or interventions and a systematic review would be too narrow.
• Identifying research gaps: Scoping reviews excel at showing where research is lacking, which can justify future studies or grant proposals.
• Exploring diverse study types: When you want to include qualitative research, case reports, guidelines, and quantitative studies together — systematic reviews are typically limited to specific study designs.
• Time constraints: When you need a publishable review article but cannot invest 12 months in a full systematic review.

Scoping reviews have gained significant legitimacy in recent years. The development of the PRISMA-ScR checklist in 2018 gave them a formal reporting framework, and many high-impact journals now actively publish scoping reviews.

The PRISMA-ScR Framework: Step by Step

PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) provides a 22-item checklist. Here is how to apply it:

1. Define Your Research Question Using PCC:

Scoping reviews use the PCC framework (Population, Concept, Context) instead of PICO:

• Population: Who are you studying? (e.g., medical students in India)
• Concept: What are you examining? (e.g., mental health interventions)
• Context: What setting or conditions? (e.g., during clinical postings)

2. Develop Your Search Strategy:

• Search at least 2-3 databases (PubMed, Scopus, and one more relevant to your topic)
• Include grey literature if relevant (conference abstracts, government reports, theses)
• Document your complete search string for each database
• Set a date range appropriate to your topic
• No language restrictions if possible (or state the restriction explicitly)

3. Screen and Select Studies:

• Title and abstract screening first, then full-text review
• Ideally two independent reviewers (discuss this with a colleague)
• Document reasons for exclusion at full-text stage
• Create a PRISMA-ScR flow diagram showing the screening process

4. Chart the Data:

This is unique to scoping reviews. Instead of extracting specific outcome data (as in systematic reviews), you "chart" key information from each study into a standardized table:

• Author, year, country
• Study design
• Population and sample size
• Key findings relevant to your question
• Any other variables specific to your review

5. Summarize and Report Results:

• Present results both numerically (how many studies, from which countries, what designs) and thematically (what did they find)
• Use tables and figures to summarize the landscape
• Identify gaps clearly — this is often the most valuable part

Protocol Registration: Where and Why

Registering your review protocol adds credibility and prevents duplication:

• Systematic reviews: Register on PROSPERO (crd.york.ac.uk/prospero). This is expected by most journals.
• Scoping reviews: PROSPERO now accepts scoping review registrations. Alternatively, publish your protocol as a separate paper or register on OSF (Open Science Framework).
• Why register: Shows you planned your methodology in advance (not adjusted to fit results). Prevents two teams from unknowingly doing the same review. Strengthens your manuscript during peer review.

Common Mistakes in Both Review Types

1. Not following the right checklist: Using PRISMA for a scoping review (use PRISMA-ScR instead) or forgetting a checklist entirely.
2. Inadequate search strategy: Searching only PubMed is insufficient. Document every database, every search term, and every filter used.
3. Single-reviewer screening: Ideally, two people independently screen studies. If truly working alone, state it as a limitation.
4. Confusing the two types: Doing quality assessment in a scoping review (usually not needed) or skipping it in a systematic review (always required).
5. Missing the PRISMA flow diagram: Both types require a flow diagram showing how you went from initial search results to final included studies.

Relevant Support

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