The Combination of Serum Total IgE and Blood Eosinophil Levels as a Predictor of Response to Phototherapy Treatment in Patients with Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease affecting approximately 25% of all people worldwide at some point during their lifetime. Although total serum immunoglobulin E (IgE) and blood eosinophil levels are not elevated in all patients with AD, they have been shown associated with AD severity. This study aimed to investigate whether IgE and blood eosinophil levels correlate with the response to phototherapy treatment, which is a second-line treatment for moderate-to-severe AD, and therefore could be considered a readily available and reliable biomarker that could guide patient management. Eighty-two patients with AD who received phototherapy at the Sheba Medical Center were retrospectively evaluated for the following: demographic characteristics, serum IgE levels, blood eosinophils count, hospitalization duration, response to phototherapy, and requirement for systemic treatment. Response to phototherapy treatment was assessed by comparing the pre- and post-treatment Investigator’s Global Assessment score for each patient in relation to the aforementioned factors. The total IgE and eosinophil levels were found to be significantly higher in patients who did not respond to phototherapy (p = 0.018 and p = 0.002, accordingly). Serum values of 1780 IU/mL for IgE and 225.0 cells/μL for eosinophils showed maximum sensitivity and specificity as predictive values for treatment response. In conclusion, this study found that high total serum IgE levels and eosinophilia were correlated with a low response to phototherapy. These results suggest that escalating treatment is recommended for patients presenting these clinical features.