D2.184 - Trends in aeroallergen immunotherapy prescription
Background
Aerollergen immunotherapy (AIT) is recommended for treating respiratory allergy refractory to environmental and pharmacotherapy measures. Current recommendations for the optimal AIT composition in poly-allergic patients remain conservative. Our goal was to analyze AIT prescription trends.
Method
Cross-sectional analysis of adults receiving subcutaneous AIT in our outpatient allergy clinic in two homologous periods (Dec/20 and Dec/24). Each cohort was divided according to the inclusion of 1 (cluster A), 2 (B) or 3 (C) groups of homologous allergens in AIT composition.
Data from both years were compared with Chi-Square test or Exact Fisher test for categorical variables and with Mann-Whitney-U test for ordinal variables. A p-value <0.01 was considered statistically significant.
Results
- 2020 cohort (n=112): 66 females (58.9%), median age 26±11.43 years [IQR: 21-38]; cluster A (85.7%, n=96): 67.7% (n=65) house dust mites (HDM), 20.8% (n=20) grass pollen (GP), 4.2% (n=4) weed pollen (WP), 3.1% (n=3) cat, 2.1% (n=2) dog, 1.0% (n=1) Plantago and 1.0% (n=1) birch pollen; cluster B (11.6%, n=13): 46.2% (n=6) HDM+GP, 15.4 % (n=2) GP+WP; 38.4% (n=5) other combinations; cluster C (2.7%, n=3): HDM+GP+Oleaceae, HDM+GP+Plantago, GP+WP+Oleaceae.
- 2024 cohort (n=193): 105 females (54.4%), median age 29±11.52 years [IQR: 22-36]; cluster A (55.4%, n=107): 73.8% (n=79) HDM, 15.9% (n=17) GP, 4.7% (n=5) WP, 2.8% (n=3) cat, 1.9% (n=2) dog and 0.9% (n=1) Plantago; cluster B (34.7%, n=67): 55.2% (n=37) HDM+GP, 16.4% (n=11) HDM+cat, 6% (n=4) HDM+dog, 6% (n=4) HDM+WP, 6% (n=4) GP+WP, 10.4% (n=7) other combinations; cluster C (9.8%, n=19): 21.1% (n=4) HDM+GP+dog, 21.1% (n=4) HDM+GP+WP, 15.8% (n=3) HDM+GP+cat, 10.5% (n=2) HDM+dog+cat, 31,6% (n=6) other combinations.
Allergen extract distribution in clusters A, B and C did not change significantly between the two time points (p=0.659, p=0.194 and p=0.197, respectively). The frequency of allergens mixtures (2 or 3 extracts) was significantly higher in 2024 (p<0.01).
Conclusion
In 2024, more patients were under AIT, with a similar profile of homologous allergens, probably mirroring stable sensitization patterns, but significantly more patients were being treated with mixtures.
Current recommendations advocate limiting mixtures to homologous, taxonomically related allergens due to concerns about dilutional effects, enzymatic degradation, and difficulties in demonstrating efficacy. Our data may indicate a growing tendency among clinicians to prioritize perceived clinical benefits over theoretical risks in real-world settings. Bridging the gap between guidelines and clinical practice remains essential to optimize AIT outcomes.
