Authors: Lesley A Stewart, Jayne F Tierney, Mike Clarke on behalf of the Cochrane Individual Patient Data Meta-analysis Methods Group.
Key points
In an individual patient data (IPD) meta-analysis, the original research data for each participant in each study are sought directly from the researchers responsible for that study;
Having access to the ‘raw’ data for each study enables data checking, thorough exploration, and re-analysis of the data in a consistent way;
IPD meta-analysis has particular benefits when the published information does not permit a good quality review, or where particular types of analyses are required that are not feasible using summary data;
Most IPD meta-analyses are carried out and published by a collaborative group, comprising a project team or secretariat, the researchers who contribute their study data, and often also an advisory group;
An IPD approach usually takes longer and costs more than a conventional systematic review relying on published or aggregate data.
18.2 The collaborative nature of IPD meta-analyses
Box 18.6.a: The Cochrane Individual Patient Data Meta-analysis Methods Group