Presentation (CTI)

OBJECTIVES: As studies evaluating whether real-world evidence (RWE) can be transported across countries become more common, particularly in the context of local health technology assessment (HTA) and emerging European Joint Clinical Assessment (JCA) processes, there is growing need for structured approaches for their review and interpretation. This study identified key methodological dimensions relevant for interpretation and synthesis of cross-country oncology RWE transportability studies.
METHODS: We assessed studies from the literature and the Flatiron FORUM research consortium comparing real-world survival outcomes across countries. Eligible studies used either individual or aggregate patient data (IPD or APD) to evaluate the transportability of real-world overall survival and/or related time-to-treatment outcomes. We reviewed these studies to identify recurring methodological dimensions relevant to evidence synthesis, including data source fit-for-purpose, difference in population characteristics, and analytic approaches.
RESULTS: Five recurring dimensions were identified across studies. First, differences in data sources, such as electronic health records and cancer registries, influenced outcome capture and comparability across healthcare systems. Second, the availability of IPD or APD affected the ability to adjust for confounding and quantify uncertainty when comparing estimates. Third, differences in patient populations and treatment patterns, including eligibility criteria and baseline characteristics influenced the transportability of findings across countries. Fourth, variation in data completeness and event timing, including missing clinical variables, differences in testing and treatment capture, left censoring, immortal time bias, and follow-up periods, affected study interpretation. Fifth, sample size and feasibility constraints, particularly in rare cancer subtypes and smaller national populations of interest, affected statistical precision and feasibility of conducting analyses.
CONCLUSIONS: These five dimensions provide a practical framework for reviewing and synthesizing cross-country oncology transportability studies. Systematic consideration of data sources, population comparability, data completeness, and analytic feasibility may improve the transparency and consistency of international RWE assessment by HTA bodies and regulators, including within evolving European JCA processes.