D2.91 - Distribution of Patients with Asthma According to the New Immune Response Classification

In 2023, the European Academy of Allergy and Clinical Immunology (EAACI) reviewed the immune response mechanisms involved in allergic diseases in the light of a new classification. In our study, we aimed to evaluate asthma patients followed up in our clinic according to the new classification of EAACI and to determine the prominent and associated groups. We also analysed whether there was a relationship between the types of immune response in patients according to the treatment step used.

Patients with asthma followed in our clinic were retrospectively classified according to their prominent endotypic/phenotypic characteristics and immune response mechanisms considering the new classification of EAACI, the details of which are given in Table 1. Additionally, demographic characteristics, treatment steps, and asthma control levels at their last visit were recorded from patient files.

A total of 226 asthmatic patients [(mean age 52.72∓13.64 years, 82.3% female (n:186), 17.7% male (n:40)] were included in the study. The mean asthma control test (ACT) at the last visit was 21.27∓4.20. Of the patients 26.5% (n:60), 27.4% (n:62) and 39.4% (n:89) were under 3rd, 4th and 5th line treatment, respectively. When the patients were classified according to the characteristics defined in Table 1; ,40.7% (n=92) were Type-1, 85.8% (n=194) were Type-4b, 16.4% (n=37) were Type-4a, 25.7% (n=58) were Type-4c, 43.4% (n=98) were Type-6, 11.1% (n=25) were Type-7, and all of them showed Type-5 immune response characteristics. When the patients were evaluated in terms of combined immune response groups, it was observed that type 4b and type 6 immune responses were the most common.  The groups showing single and combined immune response characteristics are given in Figure-1. While 35 (58.3%) of 60 patients receiving step-3 treatment showed type-1 characteristics, 32.3% and 31.5% of those receiving step-4 or 5  treatment had type-1 characteristics, respectively (p<0.001). 96.6% of those receiving step-5 treatment showed type 4b characteristics, while this rate was 71.7% in step-3 (p<0.001). Half of the patients who received step-2 treatment showed type 4a characteristics, while these rates were 11.3% and 13.5% for those under step-4 and 5 treatment, respectively (p<0.01). 96% of patients with type-7 characteristics were under step-4 or 5 treatment.

With this new classification, which defines allergic diseases based on immune response mechanisms and the combination of clinical signs and symptoms, prominent hypersensitivity groups and frequently associated groups were determined in asthma patients followed up in our clinic. To the best of our knowledge, this is the first study using this classification for asthma and we believe that our study will contribute to the literature in terms of the usability of the new classification. Further investigations of these categorised patients with in vivo techniques will be much more informative in terms of the underlying mechanisms.