A preference inversion occurs when “worse” health (instead of “better” health) along a scale or score is preferred. Our aim was to confirm past findings of EQ-5D-5L preference inversions among English-speaking respondents and to explore inversions among Portuguese-speaking respondents. Anecdotal evidence suggests that inversions may be more common in the Portuguese version, where the translation of the fourth level “severely” (gravemente) means “gravely.”
Through an infusion clinic in Tampa, Florida, United States and a cardiology clinic in Rio de Janeiro, Brazil, 740 respondents completed a tablet-based survey, which included the EQ-5D-3L and -5L followed by paired comparisons designed to assess preference inversions between the fourth and fifth levels of each of the five domains: Mobility (MO), Self-Care (SC), Usual Activity (UA), Pain/Discomfort (PD), and Anxiety/Depression (AD). An example from the AD dimension would be: “Which do you prefer? Starting today, 30 days with health problems: Severely anxious or depressed or Extremely anxious or depressed” (i.e., Level 4 AD vs. Level 5 AD).
In the English-speaking respondents, preference inversion was only observed to a substantial extent in the AD dimension (U.S. N = 470; 7% MO, 14% SC, 14% UA, 20% PD, and 45% AD). Inversions were more common among the Portuguese-speaking respondents (Brazil N = 270; 11% MO, 32% SC, 35% UA, 49% PD, and 65% AD). Specifically, 44 out of 68 Brazilian respondents (65%) preferred “extremamente” (Level 5 AD) over “gravemente ansioso (a) ou deprimido (a)” (Level 4 AD).
This evidence confirms previous findings for the U.S. English version of the EQ-5D-5L and led to a relabeling on the Portuguese version. It demonstrates the usefulness of collaboration between psychometric, econometric, and linguistic experts in developing the wording for and translating preference-based measures of health-related quality of life. Further research may explore inversions in other translations. The authors recommend that preference inversion tests should be included in the development and translation process.