Beyond sensitization: real-life thresholds for cat allergy in children

Cat sensitization is common in patients with allergic diseases and may not always produce clinical symptoms.

This study aimed to assess the correlation between skin prick test (SPT), cat-specific immunoglobulin E (cat sIgE), and symptoms in sensitized children, and to determine optimal thresholds and predictors for clinical cat allergy.

We retrospectively evaluated 1052 cat-sensitized children (2017-2024) who underwent SPT and/or cat sIgE testing. Patients were grouped by presence of cat-related symptoms, and their clinical, laboratory, co-sensitization, and exposure characteristics were compared.

Clinical symptoms developed after exposure in 39% of cat-sensitized patients. The optimal cat sIgE cut-off was 1.05 kU/L (sensitivity 71.4% and specificity 93.0%), and 4.5 mm for SPT (sensitivity 64.1% and specificity 75.9%). Multivariate analysis identified cat sIgE positivity as the only independent risk factor for symptom development (odds ratio [OR]: 23.22, 95% confidence interval [ 95% CI]: 11.62-46.39). Environmental exposure characteristics were significant in univariate analysis; in particular, contact at home (OR: 2.35; 95% CI: 1.48-3.71; P < 0.001), family visitation/indoor contact (OR: 2.99; 95% CI: 1.88-4.74; P < 0.001), and sharing a household with a cat (OR: 3.74; 95% CI: 1.78-7.85; P < 0.001) were associated with symptom development. Positivity for the house dust mites Dermatophagoides farinae (OR: 1.59; P < 0.001) and Dermatophagoides pteronyssinus (OR: 1.65; P < 0.001) and grass pollen sensitization (OR: 1.69; P < 0.001) were also significantly associated with symptomatic patients.

Cat sIgE positivity independently predicts symptoms, with 1.05 kU/L for sIgE and 4.5 mm for SPT identified as reliable diagnostic cut-offs.