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Systematic reviews and meta-analyses of individual participant data (IPD) have long been recognised as a gold standard approach. They offer many advantages over analyses that use aggregated data extracted from publications. These include: increased opportunity to identify and include unpublished studies and obtain full outcome data (thereby reducing the potential for bias arising from the absence of unpublished studies and unreported outcomes); checking and transforming data to common scores or measures; standardising analyses across studies; and undertaking more flexible and powerful statistical analyses including exploration of potential effect modifiers.

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement, published in 2009, has been adapted to provide specific guidance relating to individual participant data. The ‘Preferred Reporting Items for a Systematic Review and Meta-Analysis of Individual Participant Data: The PRIMSA-IPD Statement’, recently published in The Journal of the American Medical Association, provides a reliable and consistent set of gold standard guidelines.

The aim of these guidelines is to help researchers undertaking systematic reviews and IPD meta-analyses to report their findings in a full and transparent manner and in a way that can be understood by those who need to know about and act on their findings.

The original PRISMA Statement includes a 27-item checklist and flow diagram, predominantly used for systematic reviews and meta-analyses of randomised trials using aggregate data. The PRISMA-IPD Statement extends these guidelines by including three new criteria relating to individual participant data that help researchers to check the integrity of the data, report any issues, and explore effect, for example whether certain groups of individuals benefit more from the intervention than others. It also covers issues relating to study design, such as methods of obtaining the individual participant data, and handling trials for which individual data were unavailable.

WWARN’s Lumefantrine Pharmacokinetic/Pharmacodynamic and ACT Africa Baseline Study Groups, which are currently under peer review, have already completed their reporting using these guidelines. Going forward, all WWARN studies will adhere to these thorough and transparent reporting criteria. These guidelines enable us to ensure that our reports are standardised to the same level as other pooled analyses of patient data, helping to ensure the reproducibility of our work and careful interpretation of the findings.

Find our more information about WWARN and data sharing.


  1. Lesley A. Stewart et al. Preferred Reporting Items for a Systematic Review and Meta-analysis of Individual Participant Data: The PRISMA-IPD Statement. JAMA. 2015;313(16):1657-1665. doi: 10.1001/jama.2015.3656