How do scores obtained from the 3L and 5L compare?
Responses to the EQ-5D-5L and EQ-5D-3L may differ as their descriptive systems are different. For example, the most extreme response option on the mobility dimension is “confined to bed” in the EQ-5D-3L and “unable to walk about” in the EQ-5D-5L, which may lead to different responses from respondents. The expanded level structure and the different descriptors may also make the EQ-5D-5L more sensitive, leading to differences in responses, which may be reflected in index scores. In some countries/regions, EQ-5D-3L and EQ-5D-5L index scores will have similar properties, while in others they may be quite different. Differences in index scores are multicausal, and may reflect differences in valuation methods for deriving these scores, preferences changing over time and differences between the descriptive systems. For example, “Confined to bed” (EQ-5D-3L) is associated with larger disutility than “unable to walk” (EQ-5D-5L) (Law et al 2018), which may lead to differences between EQ-5D-3L and EQ-5D-5L index scores.