Real-world outcomes of personalized sublingual immunotherapy for environmental allergies delivered through a telemedicine platform: a retrospective longitudinal cohort study

Background: Allergen immunotherapy (AIT) is a disease-modifying treatment for IgE-mediated respiratory allergy, but real-world use is limited by access and adherence. Telemedicine-enabled sublingual immunotherapy (SLIT) may address these barriers; long-term outcomes remain incompletely characterized. Methods: = 2,897). Outcomes included symptom severity, medication use, quality of life (QoL), adherence, and adverse events. Longitudinal changes were analyzed using mixed-effects models; asthma subgroup analyses were performed. Results: Mean age was 39.0 years, 52.7% were female, and 25.3% had asthma. Median follow-up was 20 months. Symptom severity decreased, with a 10.1-point reduction at 6 months and smaller subsequent declines. Clinically meaningful improvement (≥30-point reduction) increased from 28% at 12 months to 45% at 24 months; higher baseline severity predicted earlier response (HR 2.95). Medication use declined over time (OR 2.31 per 12 months), with fewer medication categories used. QoL improvement increased from 81.4% at 12-18 months to 90.7% at 30-36 months (OR 4.68 per 12 months). Self-reported adherence was high (>90% for ≥20 days/month), and discontinuation was uncommon. Adverse events were infrequent and predominantly mild (Grade I: 11.7%); no anaphylaxis or eosinophilic esophagitis was reported. Among patients with asthma, longer treatment duration was associated with improved control, reduced inhaler use, and improved QoL. Conclusions: Personalized SLIT delivered via telemedicine was associated with sustained symptom improvement, reduced medication use, high adherence, and a favorable safety profile, supporting the feasibility and scalability of this care model in routine clinical practice.