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Background: Daily sublingual immunotherapy (SLIT) for 3 years reduces symptoms of allergic disease and induces tolerance. Real-life data from children with asthma receiving SLIT are scarce.

Objective: We used population-based data to describe characteristics, SLIT duration, and changes in morbidity in children with asthma prescribed SLIT.

Methods: The study included children (5-17 years) with asthma who were prescribed SLIT, and who were registered in the Swedish National Airway Register (SNAR) before SLIT initiation (N = 1,514), of whom 782 had post-SLIT recordings in the SNAR. Age, sex, Asthma Control Test score (≤19 denotes uncontrolled asthma), spirometry data, number of SLIT tablets dispensed, and socioeconomic background were extracted from the SNAR and other national registers. SLIT duration was classified as <4, ≥4, >12, or >24 months.

Results: SLIT was more common in boys (69%) and adolescents (71%). Most children had parents with higher education (70%), and 25% had uncontrolled asthma. SLIT duration of ≥4, >12, and >24 months was identified in 86%, 50%, and 30%, respectively. Parents with higher education were associated with SLIT duration of ≥4 months (odds ratio = 3.69; 95% confidence interval 2.75-4.96). SLIT duration of >12 months was associated with lower risk of post-SLIT uncontrolled asthma (adjusted odds ratio = 0.49; 95% confidence interval, 0.25-0.99). No associations were found between SLIT duration of ≥4, >12, or >24 months and changes in spirometry.

Conclusion: Longer SLIT duration was associated with higher education in parents and lower risk of uncontrolled asthma. Measures to improve persistence in SLIT in children with asthma may have important clinical implications.