Measurement properties of the ICECAP-A capability well-being instrument among dermatological patients

BACKGROUND: Capability well-being captures well-being based on people’s ability to do the things they value in life. So far, no capability well-being measures have been validated in dermatological patients. OBJECTIVES: To validate the adult version of the ICEpop CAPability measure (ICECAP-A) in patients with dermatological conditions. We aimed to test floor and ceiling effects, structural, convergent and known-group validity, and measurement invariance. METHODS: In 2020, an online, cross-sectional survey was carried out in Hungary. Respondents with self-reported physician-diagnosed dermatological conditions completed the ICECAP-A, Satisfaction with Life Scale (SWLS), WHO-5 Well-Being Index and two dermatology-specific measures, Dermatology Life Quality Index (DLQI) and Skindex-16. RESULTS: 618 respondents (mean age 51 years) self-reported a physician-diagnosed dermatological condition, with warts, eczema, onychomycosis, acne and psoriasis being the most common. ICECAP-A performed well with no floor and mild ceiling effects. The violation of local independence assumption was found between the attributes of ‘attachment’ and ‘enjoyment’. ICECAP-A index scores correlated strongly with SWLS and WHO-5 (r(s) = 0.597–0.644) and weakly with DLQI and Skindex-16 (r(s) = − 0.233 to − 0.292). ICECAP-A was able to distinguish between subsets of patients defined by education and income level, marital, employment and health status. Multigroup confirmatory factor analysis indicated measurement invariance across most of these subgroups. CONCLUSIONS: This is the first study to validate a capability well-being measure in patients with dermatological conditions. The ICECAP-A was found to be a valid tool to assess capability well-being in dermatological patients. Future work is recommended to test measurement properties of ICECAP-A in chronic inflammatory skin conditions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11136-021-02967-2.