Evaluation of itch intensity scales in atopic dermatitis: Differential measurement properties and associations with relevant cytokines.

Itch is the cardinal symptom contributing to patient burden in atopic dermatitis. Multiple validated itch scales are used in clinical trials, generating heterogeneous datasets. In addition, recent studies suggest an association between cytokine levels and disease severity in atopic dermatitis. This study aimed to compare the performance of different validated itch instruments and their relationship to blood cytokine profiles. Forty-nine adults with severe atopic dermatitis and severe itch were treated with 300 mg dupilumab for 16 weeks. At the initial assessment and after treatment, itch intensity and QOL were evaluated using various assessment tools. Peripheral blood samples were collected at both time points for cytokine profiling. All itch intensity scales demonstrated comparable responsiveness, irrespective of their dimension; however, the numerical rating scale consistently yielded higher scores than the visual analog scale. Macrophage-derived chemokine, CCL26, B-cell-activating factor, and IL-2R levels were significantly reduced after treatment and correlated with all (macrophage-derived chemokine and B-cell-activating factor) or subsets (CCL26 and IL-2R) of itch intensity and QOL scores. In conclusion, all validated itch intensity scales are suitable for routine clinical use; however, adhering to one instrument is recommended. The observed correlations between cytokine levels and itch scales suggest their potential as markers of disease burden in atopic dermatitis.