Once you have identified all studies to be included in the systematic review, the next step is to extract and analyze the data contained in those studies. For a qualitative (non-meta-analysis) systematic review, you will create Summary of Findings tables and Bias/Evidence Quality figures. A meta-analysis requires pooling of data and specialised statistical analysis.
The data extraction should be based on the previously defined interventions and outcomes established during the research question, inclusion/exclusion criteria, and search protocol development. If those stages have been done properly, it should not be too difficult to identify the data elements that need to be extracted from each included study.
Create a data extraction form that will be filled in for each included study. Use a software program that will allow you to create a form/questionnaire/survey and then create statistics, tables, and figures out of that data. There are a variety of these available including Microsoft Access/Excel, Qualtrics, REDCap, Google Forms/Sheets, etc.
At a minimum, Data Extraction includes: Study Characteristics; with particular detail related to characteristics, Outcome Measures of interest, and Results that you may use in data synthesis.
For Cochrane's Handbook on Preparing for Data Extraction click here.
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