Validation of the Atopic Dermatitis Control Tool (ADCT) and a Comparison with the Recap of Atopic Eczema Questionnaire (RECAP)

The Atopic Dermatitis Control Tool (ADCT) has not been validated in the Dutch population, and comparisons with the Recap of atopic eczema (RECAP) questionnaire are still lacking. This prospective study was conducted at a Dutch tertiary hospital between June 2021 and December 2022, to assess measurement properties of the Dutch ADCT in adults with atopic dermatitis (AD) and compare it with RECAP. Participants completed the ADCT, RECAP, and reference instruments including Patient's Global Assessment (PtGA), Patient-Oriented Eczema Measure (POEM), Dermatology Life Quality Index (DLQI), quality-of-life questionnaire of the EuroQol Group (EQ-5D-5L), Numeric Rating Scale (NRS) peak itch/sleep disturbance, Skindex-29, and Global Rating of Change (GRC), at baseline, 1-3 days, and 4-12 weeks. Construct validity was assessed through a priori hypotheses, whilst reliability was evaluated with standard error of measurement (SEMagreement) and intraclass correlation coefficient (ICCagreement). Interpretability was examined using anchor-based approaches. In total, 196 adults with AD were included. Among a priori hypotheses, 82% (single-score validity) and 59% (responsiveness) were confirmed. The SEMagreement was 1.15, and the ICCagreement was 0.983. The final bandings for the ADCT were established, with a binary cutoff of ≥ 6 indicating uncontrolled AD. The smallest detectable change (SDC) was 3.2, and the minimally important change (MIC) value from predictive modelling was 2.9. Furthermore, the ADCT exhibited high correlations with RECAP at all levels (most correlations being above 0.80). These results demonstrated the Dutch ADCT as a valid, reliable, and responsive tool, and have important clinical implications.