Reasons for distributional preferences for health outcomes: A mixed method interview study.

OBJECTIVES: Policy makers need information on how members of the public value improving population health (efficiency) relative to reducing socioeconomic health inequality (equity). Quantitative evidence of the trade-off using Benefit Trade-Off (BTO) is emerging, but not qualitative or mixed-method evidence. This mixed method study aimed to elicit distributional preferences among the general population in Japan over socioeconomic inequality in lifetime health using BTO tasks, and to understand the underlying reasonings. METHODS: Individual online interviews (n=50) were conducted in 2022, comprising two main elements: 1) BTO tasks; and 2) qualitative questions regarding the participant's understanding and reasonings behind their BTO task choices. RESULTS: The median BTO response was inequality averse (prioritarian). The qualitative analysis found: the relevance of non-health considerations such as prioritising the health of the rich because they make more tax contributions; violating the symmetry assumption of the standard BTO; self-interested motivations despite the exercise using a social perspective; indecisive choices; and inconsistent reasonings across BTO subtasks. CONCLUSIONS: This is the first mixed-method interview study on BTO preferences of the public, involving an in-depth qualitative component. Some of the reasonings observed were similar to those in existing qualitative studies, albeit based on non-BTO methods. The findings also suggest heterogeneous reasonings by participant gender and geographic region. Some participants gave coherent explanations for behaviour such as choosing a more unequal distribution in favour of the rich ("inequality seeking") or choosing a less unequal distribution even when nobody is better off (violation of monotonicity).