What is PROSPERO?
PROSPERO is an initiative from England and it enables the detection of systematic reviews and meta-analysis before they are fully developed and published.
This corresponds to for example www.clinicaltrials.gov where you can find clinical trials and in fact also many observational studies. Use of PROSPERO will thereby prevent unnecessary work in the planning and writing phase of a systematic review because you will be able to see what other researchers are working on before the reviews are published.
If you find out that others are working on the exact same review that you want to make, then you can change the scope or angle of your own review and then add something new and unique to science in stead of producing the exact same review that other researchers are making at the same time.
Furthermore, when you register your review and methodology at the PROSPERO database, then you will have to stick to your analysis plan when you do your data extraction and analysis.
It is a very good initiative and hopefully one day it will be mandatory to register systematic reviews and meta-analyses just as it has become mandatory to register clinical trials.