Table 1.

Benefits and challenges of IPDMA of ageing research trial data

Benefits of IPDMA	Challenges of IPDMA
Supports inclusion of IPD from unpublished trials, and analysis of unreported outcomes	Requires considerable time and resource for implementation, and cannot be done by a small volunteer team
Allows greater opportunity for standardising outcomes and covariate definitions	Needs a team of researchers with requisite expertise in managing and preparing IPD
Enables independent scrutiny of original trial data	Estimating how long the IPDMA will take can be difficult, because progress is not entirely under control of the research team
Supports more reliable risk of bias assessment	Obtaining funding for IPDMA can be challenging because of uncertainties in how much IPD will be available and how much time will be needed for the project
Enables application of a consistent method of analysis across trials	Obtaining ethical approval can be challenging because different requirements may be required across different countries that the IPD is requested from
Provides greater power for investigating how participant characteristics predict treatment effects	Development and approval of data sharing agreements can be time consuming, requiring agreement across multiple institutions
Can increase generalisability of findings by weighing the IPD based on population-level data	Despite all appropriate preparation, it is possible that original trialists may not agree to share IPD, or withdraw agreement at a later date
Enables discussion of implications of findings with a multidisciplinary group of researchers including original trial investigators	Potentially small number of common variables across trials and multiple outcome measures in use across different domains relevant for ageing research (for example ADL, cognition, health-related quality of life) mean that data harmonisation can be especially challenging
Supports wider dissemination of findings through collaborative networks, patient groups and the wider public	Even with access to IPD, it is possible that required data may not be available in a format suitable for the planned analysis