Close
Found 0 results for your search. Showing 0 to 0.
No results could be found for your search.
x Close Search
Close

Review methods, key steps and data collection in evidence synthesis

Typically, conducting an evidence synthesis encompasses nine steps which you can see below.

 

Flowchart showing steps of evidence synthesis process
Figure 4: Typical steps of an evidence synthesis. The order can vary and can include some back and forth. Some of the steps such as appraising the risk of bias (or quality) and the level of certainty in the evidence do not apply to some types of evidence (e.g., evidence maps and evidence and gap maps).

 

Here is a summary of each of these steps:

  1. Formulate the review question: Clearly define the question you aim to answer through your review. This often involves specifying the population, intervention, comparison, and outcomes (PICO) of interest.
  2. Develop a protocol: Outline the rationale, hypothesis, and methodology for the synthesis. This protocol acts as a roadmap for the entire process. It is best practice to register or publish protocols in advance of starting a review to ensure transparency and reduce the risk of bias. This step includes designing a search strategy and identifying relevant databases/ sources of information.
  3. Conduct a systematic search: using pre-specified search terms, search and retrieve relevant studies from various databases and sources, including grey literature.
  4. Screen studies: Assess the identified studies for relevance and eligibility based on predefined criteria outlined in the protocol.
  5. Extract data: Collect relevant data from the studies for analysis according to the data extraction fields identified in the protocol.
  6. Assess risk of bias or study quality: Evaluate the quality and potential biases of the included studies. Various tools exist to assess the risk of bias of studies, depending on the types of studies included in reviews.
  7. Synthesise data: Combine the data using appropriate methods, such as meta-analysis or narrative synthesis.
  8. Assess the level of certainty in the evidence using the GRADE (Grading and Recommendations Assessment and Evaluation) framework (or CERQual for qualitative reviews), where applicable.
  9. Report the findings: Present the results in a structured format, often following guidelines like PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses).