Once you have selected the most relevant studies the next step involves extracting the relevant data, and synthesising or compiling your findings using textual or statistical methods. Rapid reviews often only include a narrative summary or descriptive synthesis. A meta-analysis is usually not included in a Rapid Review. 

"The synthesis that is conducted is often limited to a basic descriptive summary of studies and their results, rather than the full synthesis that is recommended for systematic reviews. Most rapid reviews present conclusions, recommendations, or implications for policy or clinical practice as another component of the synthesis. Multiple experts also recommend that rapid reviews clearly describe and discuss the potential limitations arising from methodological choices " (King et al., 2022)

Cochrane in their most recent advise for Rapid reviews recommends using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach to assess certainty of evidence if time and resources allow, using GRADEpro, an open access software tool for rating certainty of evidence in evidence syntheses to apply GRADE. To speed up the process they recommend that this only be applied main intervention and comparator and focus on critical outcomes and have one person complete the GRADE assessment, with a second person to verify the assessment. (Garritty et al., 2024a)

Qualitative Synthesis

A qualitative synthesis is a narrative, textual approach to summarizing, analysing and assessing the body of evidence included in your review. It is a necessary part of all systematic reviews, even those with a focus on quantitative data.

A qualitative synthesis provides the following:

• A general summary of the characteristics and findings of the included studies.
• An analysis of the relationships between studies, exploring patterns and investigating heterogeneity.
• Discusses the applicability of the body of evidence to the review's question within the PICO structure.
• Explains the meta-analysis (if appropriate to the study) and interprets and analyses the strength of results. For more information on the meta-analysis process, please view the paragrap below.
• Critiques the strengths and weaknesses of the body of evidence, including a cumulative assessment of the risk of bias across various studies.
• Discusses any gaps in the evidence, such as patient populations that have been inadequately studied or for whom results differ.
• Compares the review's findings with current conventional wisdom when appropriate.