Background. To incorporate the spillover effects experienced by carers providing informal care in health policy decisions, new carer-related preference-based measures have been developed for use in economic evaluation, which include the Adult Social Care Outcomes Toolkit for Carers (ASCOT-Carer), Carer Experience Scale (CES), and Care-Related Quality of Life (CarerQoL). The aim of this study was to investigate the extent to which these 3 instruments measure complementary or overlapping constructs. Methods.