The Hidden Burden of Polysensitization in Allergic Rhinitis: A Propensity‐Matched Real‐World Analysis of Subcutaneous Immunotherapy

OBJECTIVE: To compare the efficacy and safety of house dust mite (HDM) subcutaneous immunotherapy (SCIT) between monosensitized and polysensitized allergic rhinitis (AR) patients, and evaluate the independent impact of polysensitization on SCIT outcomes. STUDY DESIGN: Large retrospective real-world cohort study. SETTING: Tertiary referral center. METHODS: AR patients completing a 3-year HDM-SCIT regimen between January 2011 and January 2019 were included. Based on allergen profiles, patients were classified as monosensitized or polysensitized. Propensity score matching balanced baseline characteristics. SCIT efficacy and adverse events were compared before and after matching. Multivariable regression assessed the independent effect of polysensitization on SCIT outcomes. RESULTS: 1584 patients were enrolled (994 monosensitized and 590 polysensitized). Before matching, polysensitized patients exhibited higher baseline symptom scores, older age, longer AR duration, more frequent dose modifications, greater prevalence of family history of allergy, and increased asthma comorbidity. After matching, polysensitized patients showed significantly less symptom improvement and lower overall efficacy at both SCIT 1 and 3 years (P < .05). The incidence of local reactions (LRs) was also significantly higher (P < .05), while systemic reaction rates did not differ. Multivariable regression confirmed polysensitization as an independent risk factor for reduced SCIT efficacy and increased LRs (P < .05). CONCLUSION: Polysensitization was linked to reduced SCIT efficacy and a higher risk of LRs. These results underscore the value of allergen profiling and support personalized SCIT strategies and closer monitoring for polysensitized patients.