The document discusses the comparability of patient-reported outcome (PRO) data between populations and settings. It raises two key issues with assuming comparability. First, PRO instruments may not capture health attributes or describe health consistently across cultures and languages. Second, how individuals perceive and report their own health can depend on social and contextual factors like expectations, education levels, and access to healthcare. The document cautions that relying solely on self-reported health data to assess healthcare or medical strategies without addressing these issues can be misleading. It then outlines the agenda for a conference session that will address conceptual and linguistic challenges to cross-cultural PRO comparability, methods for examining differences in response category use, and approaches for handling heterogeneity in PRO data.