100631 - Long-term post treatment benefits of house dust mites sublingual immunotherapy in polysensitized children

There are concerns on efficacy of sublingual allergen immunotherapy (SLIT) in polyallergic patients, who consist the most of real clinical practice population. Immunoregulative and anti-inflammatory potency could explain non-specific antiallergic action of SLIT, especially for patients with allergic bronchial asthma (AA). Study aim was to assess long-term rate of allergen-induced AA attacks caused by non-targeted allergens in polyallergic patients, treated with house dust mite (HDM) SLIT.

56 patients (38, 67.9%, boys), aged 7-10 years, had started their HDM SLIT (natural extract drops, 300IR/ml) course in 2017 and continued it for 3.5 to 5 years, most of the group (45 pts, 80.4%) completed 4 years treatment. After SLIT completion patients continued every 6 months assessment at tertiary out-patient pediatric allergic center for 3 years. Every visit each patient reported number of asthma attacks and emergency medication utilization rate and reasons (acute respiratory infection or allergen contact) during previous 6 month; GINA asthma control questionnaire and spirometry with bronchodilator test were also performed. 

All patients completed HDM SLIT course, conserved mild/moderate AA (41pts, 73.2%) or converted from moderate to mild AA (15 pts, 26.8%). Daily inhalational corticosteroids (ICS) as maintenance treatment were utilized by 43 pts (76.8%) on the beginning of treatment, 20 pts (35.7%) on SLIT completion (p=0.001) and 24 pts (42.9%) at follow-up (p=0.01).

Included patients were clinically relevant sensitized to cats in 37 (66.1%) cases, dogs in 17 (30.4%) cases, molds in 10 (17.9%) cases before SLIT start (31 patients, 51.4%, had 3-5 culprit allergens). Number of causative allergens did not affect SLIT completion.

We did register significant decrease of AA attacks per patient per 6 month (Me [Q25; Q75]) both non-HDM allergen-induced (direct pet or mold contact) (2.8 [1.7; 3.2] on the beginning of treatment, 0.8 [0.4; 1.5] on SLIT completion and 0.9 [0.7; 1.3] at follow-up (p=0.006)) or induced by acute respiratory infection (ARI) (1.6 [0.9; 2.0] on the beginning of treatment, 0.3 [0.2; 0.5] on SLIT completion and 0.6 [0.2; 0.8] at follow-up (p=0.002)). 

Polyallergic children completed HDM SLIT decrease number of asthma deteriorations irrespectively of culprit allergens or ARI. This effect lasts non less than 3 years after SLIT completion.