Purpose: The ICEpop CAPability measure for Older people (ICECAP-O) is intended for use in economic evaluations of care services for older people. Although studies support the validity of the ICECAP-O, it does not directly ask older people about their health. This raises questions about its ability to capture health indirectly. Previous studies found mixed results in this aspect, especially for physical health. This study further investigates whether the ICECAP-O indirectly includes health.
Methods: Using a cross-sectional design, a sampling agency retrieved data from 516 people aged 70 and older from the UK through an online questionnaire. The overlap in underlying constructs of the ICECAP-O and EQ-5D-5L was assessed using exploratory factor analysis. Spearman correlations and variance analysis were conducted by relating the ICECAP-O to measures of physical, mental and social functioning.
Results: The ICECAP-O and EQ-5D-5L items loaded on two factors. Their overlap was limited, as four out of five EQ-5D-5L items loaded on the first factor, while four out of five ICECAP-O items loaded on the second. The ICECAP-O correlated highly with (mental and social functioning) health measures, and was able to differentiate between individuals with different scores on these measures. However, the correlation with the Barthel Index, a measure of physical functioning, was moderate.
Conclusions: The ICECAP-O may not fully cover all aspects of health. Therefore, a complementary health measure should be used in addition to the ICECAP-O to capture the full benefits of care interventions for older people in economic evaluations.
Keywords: Health; Patient-reported outcomes; Quality of life; United Kingdom; Validity; Wellbeing.