D1.225 - Long-term adherence to seasonal allergen immunotherapy: a 3-year (22/23-24/25) retrospective study on 174 patients

Allergen immunotherapy (AIT), with a subcutaneous (SCIT) or sublingual (SLIT) administration, is the only disease-modifying treatment for allergic diseases, but its efficacy requires at least 3 years adherence. In clinical practice, one of the biggest challenge is patient’s compliance. This retrospective study analyses adherence rates alongside the demographic and clinical factors associated with drop-out in a cohort of 174 patients during a cycle of 3 years.

We considered 107 (61%) males and 67 (39%) females who started AIT in the 2022/2023 season.

The predominant allergen was grass pollen (32%) or a mix grass and birch pollens (37%). Ninety-four patients (54%) had rhinitis alone, while 80 (46%) had rhinitis and asthma, the majority (45 pts, 56%) mild-intermittent form (GINA 1-2).

Males and females chose SCIT and SLIT at similar rates, with approximately 32% of patients opting for SCIT and 67% for SLIT; as expected SLIT was preferred in the paediatric group (5-14 years), 87.5% for females and 75% for males.

Considering the entire cohort, a higher adherence was observed in females: 86% for SCIT and 94% for SLIT. Meanwhile, the 3-year adherence in males was 77% for SCIT and 72% for SLIT. The majority of women who drop-out were foreigners who changed residence, 87.7% in the first year and 20% in the second.

Other reasons for discontinuation included personal troubles and minor adverse events (oral discomfort) with SLIT, resulting in early drop-outs. Ninety percent of those who drop out after the second year had chosen SLIT (p=0.07). Meanwhile, only 13% of patients with rhinitis and mild-intermittent asthma dropped out in the first 2 years (p=0.02)

SLIT has been preferred by patients, approximately in a 2:1 ratio, even though its’ associated with a higher drop-out (90% in the first 2 years). Although less frequently chosen in our case study, SCIT shows better adherence. The best adherence is found in the female sex, even if not statistically significant. Patients suffering from rhinitis and mild intermittent asthma (GINA 1-2) appear to be more adherent compared to those who had only rhinitis or rhinitis and moderate asthma (GINA 3).