Demonstrating transportability of real-world evidence: what do HTA bodies and health technology developers need?

Real-world evidence (RWE) is reshaping how health technology assessment (HTA) bodies evaluate therapies, yet a critical gap persists: while transportability methods enable researchers to adapt treatment effect estimates from RWE studies in another jurisdiction to local contexts, the field remains unclear on when these analyses impact decision-making. This article synthesizes insights from HTA bodies, health technology developers (HTDs), and methodologists to clarify what is missing from today's transportability conversation. We find that methodological progress has outpaced guidance on its utility; HTDs risk investing in transportability analyses without clear evidence that they reduce key uncertainties or affect recommendations. We identify three fundamental gaps: the absence of objective thresholds for determining whether transportability assumptions are adequately met; limited guidance on when quantitative transportability is needed versus qualitative assessment; and variation in HTA bodies' evaluation and application of transported evidence. These gaps create a critical impasse where HTDs must decide whether to invest in such analyses, while HTA bodies lack standardized frameworks for their assessment. We argue that transportability cannot transition from academic exercise to a decision-making tool without explicit early dialogue between stakeholders, transparent reporting standards, and capacity building within HTA bodies. We present actionable recommendations to build HTA expertise, create a case study repository, and define contexts where transported RWE demonstrably impacts patient access. As evidence dossiers increasingly rely on nonlocal data, addressing these strategic and operational gaps becomes essential to help patients.