[Allergic profile characteristics and clinical application trends in patients undergoing immunotherapy for cat and dog hair allergens: a retrospective analysis from 2019 to 2023].

Objective: To investigate the clinical demand for subcutaneous immunotherapy (SCIT) with pet allergens and explore the sensitization characteristics of patients undergoing pet SCIT. Methods: A cross-sectional retrospective analysis was conducted on patients diagnosed with pet allergies and treated with pet allergen SCIT in our outpatient clinic from January 2019 to December 2023. Patients were categorized into three groups based on the type of SCIT received: single-cat SCIT group, single-dog SCIT group, and combined cat-dog SCIT group. Results: A total of 931 patients were included, the age range was 5-65 years (median age of 30 years), with 283 male and 648 female. Among them, 67.7%(n=630) received single-cat SCIT, 10.9% (n=102)received single-dog SCIT, and 21.4% (n=199) received combined cat-dog SCIT. The number of patients receiving pet allergen SCIT increased annually. Patients in the single-dog SCIT group were significantly older than those in the other two groups (H=41.329,P<0.001) and had a lower prevalence of allergic rhinitis (91.2% vs. 96.5% and 98.5%; χ²=10.400,P=0.006). In the combined cat-dog SCIT group, the allergy rate to mold allergens was significantly higher than in the single-cat SCIT group (12.6% vs. 4.9%, χ²=13.965,P=0.001). In the single-dog SCIT group, the allergy rate to spring pollen allergens was significantly higher than in the other two groups (χ²=15.731,P<0.001), and the allergy rate to autumn pollen allergens was significantly higher than in the single-cat SCIT group (χ²=13.459,P=0.001). There was no significant difference in the dust mite allergy rate among the three groups(χ²=4.117,P=0.129). In the single-dog SCIT group, patients with asthma were significantly older than those without asthma (41.2 vs. 35.2 years old,t=-2.073,P=0.041). In both the single-cat and single-dog SCIT groups, the proportion of allergic rhinitis in the asthma group(91.2%,78.3%) was significantly lower than that in the non-asthma group(97.4%,94.9%) (χ²=8.863,6.158;P=0.008,0.026). In the single-cat SCIT group, non-asthmatic patients were significantly more likely to receive SCIT combined with spring pollen allergens compared to asthmatic patients (23.9% vs. 11.0%, χ²=7.586,P=0.006). Conclusions: The demand for pet allergen SCIT has steadily increased over the years, with a predominance of female patients. Sensitization profiles varied among patients receiving SCIT for different pet allergens. This study comprehensively elucidates the clinical demand and sensitization characteristics of patients undergoing pet allergen SCIT, providing valuable reference data for clinical diagnosis and treatment.