Prognostic Calculator of the Clinical Response to Antihistamines in Chronic Urticaria: External Validation

Antihistamines (antiH1) are the first-line treatment for chronic spontaneous urticaria (CSU), but 40% to 60% of patients do not achieve clinical control with this therapy. Early identification of the non-responder patients could undergo prompt initiation of other therapies.

To achieve external validation of a prognostic calculator of clinical response to antiH1 in adult patients with CSU.

The prognostic calculator consisted of five variables easily accessible during clinical appointments (age, angioedema, anxiety or depression, duration of the disease, nonsteroidal anti-inflammatory drug hypersensitivity, and urticaria activity score (UAS). Patients with CSU from four countries were evaluated before and after antihistamine administration. Calibration and discrimination were used to evaluate prognostic accuracy. The main outcome, clinical response to antihistamines, was evaluated with the UAS for 7 days (UAS7). Control was defined as a UAS7 score less than 6 and no control was defined as UAS7 greater than 7 points.

A total of 542 patients were included. The prognostic model performance demonstrated consistency (accuracy of 78.6%; Hosmer-Lemeshow, 0.89; area under the curve, 0.829). The model correctly predicted 82.9% of patients with UAS7 greater than 7 and 72.7% of patients with UAS7 less than 6. Patients without antiH1 control had more frequent autoimmune disease and inducible urticaria, and patients with antiH1 control had higher levels of total IgE and a higher frequency of IgE anti-thyroperoxidase, IgE anti-eosinophil peroxidase and IgE anti-eosinophil cationic protein.

This prognostic calculator was demonstrated to be a useful tool in clinical practice for an early personalized therapeutic approach according to the individual probability of response with antihistamines, potentially reducing time with suboptimal treatments.