Validation of the ICECAP-O for assessing wellbeing in people with mild dementia in Denmark

Background: Assessment of wellbeing is essential in the context of chronic diseases. The Investigating Choice Experiments for the Preferences of Older People–Capability Index (ICECAP-O) is a generic wellbeing measure beyond health. We aimed to assess whether ICECAP-O is a valid measure of capability-wellbeing in people with mild dementia by assessing its discriminative and convergent validity. Further, we assessed its feasibility, internal consistency, and test-retest reliability. Methods: Four quality-of-life (QoL) and wellbeing measures were completed by 123 community-dwelling people with mild dementia. Discriminative validity was assessed by the ability of ICECAP-O to distinguish between levels of QoL, wellbeing, and related variables. Convergent validity was assessed by correlations between ICECAP-O index and domain scores, and the 5-level EQ-5D version (EQ-5D-5L), European Quality of Life visual analog scale (EQ VAS), Engagement and Independence in Dementia Questionnaire (EID-Q), and the World Health Organization Wellbeing Index (WHO-5). The feasibility of ICECAP-O in people with mild dementia was evaluated by missing data analysis. Internal consistency was assessed with Cronbach’s α, and test-retest reliability was assessed using intraclass correlation coefficient (ICC). Results: ICECAP-O significantly distinguished between different levels of QoL and wellbeing. Further, ICECAP-O was not affected by sociodemographic characteristics. ICECAP-O index scores were strongly correlated with EQ-5D-5L (ρ = 0.61) and EID-Q (ρ = 0.62), and moderately with WHO-5 (ρ = 0.58) and EQ-VAS (ρ = 0.58). Missing data on ICECAP-O dimensions, ranging from 2% to 3%, indicate good feasibility in people with mild dementia. ICECAP-O demonstrated acceptable internal consistency (α = 0.74) and good test-retest reliability (ICC = 0.86). Conclusion: The Danish version of ICECAP-O is a valid and reliable measure of wellbeing in people with mild dementia, and demonstrated acceptable psychometric properties, providing further evidence for its use in this population.