Assess the Need | Assemble the Team | Refine the Question | Select the Review Type | Learn More
Start your evidence synthesis review right.
Before you dive in:
- Assess the need for your review.
- Assemble your team. You need 2+ people with enough time to commit.
- Refine your research question. It sets the direction of your review.
- Select the type of review that fits your question and resources.
- Learn more about evidence synthesis. Acquire the necessary skills and knowledge.
Why this matters: The right preparation improves the clarity, quality, and impact of your review.
Above text generated with artificial intelligence: https://writingforbusyreaders.com/ai/
Assess the Need
You might not conduct an evidence synthesis review if:
- A recent, high-quality review addresses your research question
- Little or no original research has been published on your topic
- You are looking for an easy publication
- You want to describe a broad topic
- You do not have a sufficient number of team members
- You do not have enough time
If you decide not to conduct an evidence synthesis review, consider a narrative review. A narrative review is a more flexible approach, allowing you to address a broad topic as a small team or individual author. NIH Librarians can help with those, too!
Assemble the Team
Evidence synthesis reviews require teams of 2 or more to avoid bias in their conduct. Plan for specific roles and responsibilities on your review team:
- Include subject matter and methods experts and a librarian
- Establish roles, communication expectations, deadlines, and authorship early
For more information on this important step, see Review Team & Roles.
Refine the Question
The research question determines the evidence synthesis review type, screening criteria, data to extract, and the approach to data synthesis.
Clarify your research question
- The process helps teams define concepts and gain a shared understanding of purpose
- Invest time in defining the review question to improve clarity and communicate value [Cochrane Training: video; 2 minutes]
- An unclear research question leads to the team wasting time and effort, from screening an unnecessarily large results set to redoing screening to an inability to synthesize included studies.
Use frameworks to help structure your question
- Select a framework according to the research domain and type of question
- Describe each element of the question so it can be clearly understood by team members and future readers
- The PICO format is an example of a common framework used for clinical topics
- Patient Intervention Comparator Outcome (PICO) Framework [Cochrane UK: Video; 3 minutes]
- Example: In patients with systemic lupus erythematosus [population], is consuming turmeric tea [intervention] more effective than Plaquenil [comparison] for reducing joint pain [outcome]?
- PCC works well for scoping reviews
- Population Concept Context (PCC)
- For patients with systemic lupus erythematosus [population], what patient-reported outcome measures [concept] are used in trials of pain relief [context]?
Attend the NIH Library Training Developing the Research Question and Conducting the Literature Search and contact the NIH Library’s Evidence Synthesis Service for additional help and information.
Select the Review Type
Your choice depends on your question, team, and timeline.
Use this table to explore and select from various evidence synthesis review types. If you have a question different to the examples below, reach out to the NIH Library’s Evidence Synthesis Service for information on other review types.
| Review Type | Manual & Reporting Guidelines | Example Question | Further Learning |
|---|---|---|---|
| Systematic reviews answer specific questions, often on effectiveness, diagnostic test accuracy, prognosis, or epidemiology | In pregnant people, what is the impact of access to cooling centers during heat waves on premature birth? | What are systematic reviews? [Cochrane: Video, 3 minutes] | |
| Scoping reviews clarify concepts, describe how research is done, and expose research gaps or areas ready for systematic reviews | JBI Manual for Evidence Synthesis chapter 10: Scoping reviews | What research has been conducted on the impact of extreme heat on fertility? | Scoping reviews: an overview with examples [Cochrane Training: Video; 7 minutes] |
| Umbrella reviews compile high-quality evidence from prior reviews | JBI Manual for Evidence Synthesis chapter 9: Umbrella reviews | What is the impact of climate-related events on pregnancy outcomes? | What are Umbrella Reviews? [JBI: Video; 1:30 minutes] |
| Rapid reviews support decision makers in a timely fashion by synthesizing evidence | Rapid Review Guidance Document (AHRQ) Rapid Review Guidebook (National Collaborating Centre for Methods and Tools) | What is the impact of wildfire smoke on pregnancy outcomes? | What are Rapid Reviews? [JBI: Video; 8 minutes] Difference between systematic reviews and rapid reviews [Cochrane Training: Video; 5 minutes] |
Additional suggestions on selecting the right type of evidence synthesis review are:
- If you don’t have at least 2 people and at least 1 year (Borah et al. 2017), consider a narrative review
- Select the right review type using this interactive tool or decision tree
- Attend the NIH Library training Literature Reviews: Select the Right Type
Learn More
Evidence synthesis reviews are methodologically rigorous and share common steps, from developing the protocol through searching and screening the literature, to synthesizing results and publishing your work. Learn more below.
Manuals and Handbooks
- JBI Manual for Evidence Synthesis
- Cochrane Handbook for Systematic Reviews of Interventions
- AHRQ Methods Guide for Effectiveness and Comparative Effectiveness Reviews
- Systematic Reviews: CRD’s Guidance for Undertaking Review in Health Care
Videos
Additional Tips
- Knafl K, Whittemore R. Top 10 Tips for Undertaking Synthesis Research. Res Nurs Health. 2017 Jun;40(3):189-193. doi: 10.1002/nur.21790. Epub 2017 Mar 7. PMID: 28267870.
Good luck, and please reach out to us for guidance or with questions!