The European Quality of Life 5 Dimensions 5 Level Version (EQ-5D-5L) has shown potential limitations in capturing key aspects of health-related quality of life in dermatological diseases. This study investigated the psychometric properties of the EQ-5D-5L and 5 bolt-ons—skin irritation (itching, IT), self-confidence (SE), social relationships (SR), social participation (SP), and feeling connected (FC)—in 2 prevalent dermatological conditions.
A cross-sectional online survey was conducted with n = 180 atopic dermatitis (mean age: 37 years) and n = 285 psoriasis patients (46 years) in Germany. Outcome measures included the EQ-5D-5L, 5 bolt-ons, and Dermatology Life Quality Index, Skin Shame Scale, Patient-Oriented Eczema Measure, and Psoriasis Signs and Symptoms Diary. Analyses comprised ceiling, construct and known-groups validity, and EQ VAS explanatory power.
Adding IT led to the largest reduction in ceiling of the EQ-5D-5L (from 15.5% to 5.6% in atopic dermatitis, and 18.7% to 10.7% in psoriasis), followed by SE (atopic dermatitis) and FC (psoriasis). Overall, 72% of atopic dermatitis and 54% of psoriasis patients reporting no pain/discomfort reported problems with IT. IT correlated strongly with conceptually overlapping items of the Dermatology Life Quality Index, Patient-Oriented Eczema Measure, and Psoriasis Signs and Symptoms Diary. Adding IT improved known-groups validity and explanatory power, whereas additional bolt-ons offered limited additional impact. No meaningful differences emerged between SR and SP bolt-ons.
In this patient sample from Germany, IT performed best, with minimal added value from other bolt-ons. IT is a promising candidate bolt-on for recommendation in chronic inflammatory skin diseases. Future research may explore the usefulness of other potentially relevant bolt-ons (eg, sleep) in these patient populations.