Examining the face validity of the EQ-HWB-9 in dementia: caregiver interpretation across “Today” and “7-Day” recall periods

BACKGROUND: This study aimed to assess the face validity of the EQ Health and Wellbeing 9 (EQ-HWB-9) for use as a proxy by informal caregivers of community-dwelling people living with dementia (PlwD). It explored how caregivers understand and interpret the EQ-HWB-9 items when using two different recall periods (today vs. 7-days). METHODS: Qualitative interviews were conducted with 73 informal caregivers of PlwD in Germany. Participants were randomly assigned to one of two recall period groups of the EQ-HWB-9 ("today" vs. "7 days"), and underwent an interview, designed to evaluate the appropriateness of the EQ-HWB-9. Interviews were audio-recorded, transcribed verbatim, and analyzed using qualitative content analysis. RESULTS: Caregivers were, on average, 70.6 years old and mainly female (72.6%). Most caregivers found the EQ-HWB-9 acceptable, highlighting its broad health coverage, clear structure, and suitability of the five-point response scale. Criticisms included the brevity and insufficient depth to capture the PlwD's health status fully. Caregivers tended to focus on observable aspects, such as daily activities, concentration, and mobility, while internal states, like loneliness, sadness, and anxiety, were more challenging to assess, often relying on indirect cues. The 7-day recall period was associated with lower adherence and more frequent deviations from recall instructions compared to the "Today" recall. Overall, caregivers adhered well to the instructed proxy-proxy perspective but reported uncertainty in selecting the most appropriate responses. CONCLUSIONS: The EQ-HWB-9 is generally acceptable and feasible for proxy assessments in PlwD. However, challenges regarding recall periods, proxy interpretation, and response certainty require further investigation.