Reframing Population-Adjusted Indirect Comparisons as a Transportability Problem: An Estimand-Based Perspective and Implications for Health Technology Assessment
The paper reframes Population-Adjusted Indirect Comparisons (PAICs) as a transportability problem: can an effect from one patient group be validly applied to another? It distinguishes between within-population properties and cross-population validity, establishing strict criteria for when PAIC estimates are directly transportable and when they must be treated as population-specific.