Participating trials in a PMA usually supply individual patient data once their individual trial is completed and published. The advantage of the PMA design is that trialists prospectively decide what data they will collect and in what format, making the need to redefine and recode supplied data less problematic than is often the case with a retrospective IPD. The PMA should develop a data transfer protocol that may incorporate current data interchange standards, such as those developed by the Clinical Data Interchange Standard Consortium (CDISC; www.cdisc.org).
Once data are received by the PMA Secretariat, they should be rigorously checked using the same procedures as for IPD meta-analyses, including checking for missing or duplicated data, running data plausibility checks, assessing patterns of randomization and ensuring the information supplied is up to date (see Chapter 18, Section 18.4.4). Data queries will be resolved by direct consultation with the individual trialists before being included in the final dataset for analysis.