Once the final list of papers to be included in the review is finalised, the data needs to be extracted.

The type and amount of data extracted will depend on the design and purpose of the review.

Items 10 and 11 in the PRISMA 2020 checklist (p.1) relate to the data extraction process:

• Data collection process: Item 9 - "Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process."
• Data Items: Item 10a -   "List and define all outcomes for which data were sought. Specify whether all results that were compatible with each outcome domain in each study were sought (e.g. for all measures, time points, analyses), and if not, the methods used to decide which results to collect.”
• Data Items: Item 10b - "List and define all other variables for which data were sought (e.g. participant and intervention characteristics, funding sources). Describe any assumptions made about any missing or unclear information."

For more detailed information and guidance regarding the data extraction refer to the Cochrane handbook, Part 2: Chapter 5: Collecting data. It provides a checklist of items to consider