Differences in Itch Quality Between Interleukin-31 and Thymus and Activation-Regulated Chemokine of Japanese Atopic Dermatitis.

Objective: To elucidate the relationships among various itch qualities, blood biomarkers, and patient-reported outcome measures (PROMs) in atopic dermatitis (AD), we characterized 10 qualities of itch (QoIs) in adult Japanese patients with AD and examined their associations with blood biomarkers as well as objective and subjective clinical measures. Patients and Methods: The QoI was assessed by a translated 10-item questionnaire. The relationship among each QoI and blood biomarkers (including interleukin [IL]-31, thymus and activation-regulated chemokine [TARC], and lactate dehydrogenase levels; differential white blood cell counts, including eosinophil, basophil, and neutrophil relative counts; and total immunoglobulin E levels); PROMs, such as visual analog scale and patient-oriented eczema measure; and objective measures, such as eczema area and severity index, was evaluated. Results: Patients with AD frequently suffered from a sensation similar to crawling like ant (crawling) and stinging and burning sensations. Crawling was positively correlated with serum IL-31 levels but not serum TARC level. Stinging and stabbing sensations were positively correlated with serum TARC level but not with serum IL-31 levels. Stinging, stabbing, and burning sensations were correlated with PROMs and eczema area and severity index. Our limitation is that other cytokines, such as IL-4 and IL-13, were not measured. Conclusion: The QoI in Japanese patients with AD could be classified into IL-31-related and TARC-related types. Our findings suggest relationships between crawling and IL-31 and between stinging and stabbing and TARC in Japanese patients with AD.