A rapid review is currently held generally as a modification of the systematic review that is "streamlined" primarily in the interest of time. Since the proper conduct of the conventional systematic review (with or without meta-analysis) takes tremendous time as a function of the number of potentially-eligible studies, it may often not be the ideal design to provide evidence-based guidance on acutely-pressing questions, such as during the first few months of the COVID-19 pandemic. Rapid reviews reduce the time to conduct evidence synthesis by omitting and/or simplifying at least one step of the conventional systematic review process (such as restricting the search to online-released preprints and published literature only, discarding the risk of bias/quality assessment of included studies, etc.).

A major concern in rapid reviews right now is that there is yet to have strong, uniform guidance on how to conduct them, and rapid review groups often vary on what steps of the conventional systematic review process are omitted/streamlined. Please read the following reference on the topic if you have time: Article A scoping review of rapid review methods

I think @Aedrian Abrilla nicely explained the critical difference between rapid review and systematic review. To reiterate, to some extent, a rapid review a compromised version of the conventional systematic review due to time constrained. For example, according the article, 82% of rapid reviews streamlined the methods of conventional SR.

Systematic review: Seeks to systematically search for, appraise and synthesize research evidence, often adhering to guidelines on the conduct of a review. Aims for exhaustive, comprehensive searching. Quality assessment may determine inclusion/exclusion. It can be with or without meta-analysis.

Rapid review: Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. Completeness of searching determined by time constraints.

thanks these have been super helpful

Thank you for all the answers, however If I may ask, which part of the conventional systematic review is streamlined in the rapid review? Aedrian Abrilla Proloy Barua Sajesh K Veettil

A systematic review is usually very resource intensive and takes about 12-24 months to complete.

A rapid review follows most of the principle steps of a systematic review, using systematic and transparent methods to identify, select, critically appraise and analyze data from relevant research

Rapid Review vs. Systematic Review: What are the differences?

https://www.heardproject.org/news/rapid-review-vs-systematic-review-what-are-the-differences/

A rapid review (or rapid evidence assessment) is a variation of a systematic review that balances time constraints with considerations in bias.

https://guides.library.vcu.edu/rapidreview

A nice explanation have shared herein!

Very informative discussion

Thanks for the inputs Abdelghani Rouini

Rapid review: usually based on the systematic reviews thus saving time, often use descriptive analysis only; Systematic review: time cost as systematically review all the best evidences that beyond systematic reviews , often use both qualitative analysis and quantitative analysis (i.e. meta analysis)