Effectiveness and Safety of Subcutaneous Immunotherapy for Respiratory Allergy to Dermatophagoides spp. and Grass Pollen

Allergen immunotherapy combining mite and grass pollen extracts may offer a practical option for polysensitized patients, but real-world evidence remains limited. This multicentre, retrospective, non-controlled, longitudinal study evaluated the effectiveness and safety of two subcutaneous immunotherapy formulations containing glutaraldehyde-polymerized Dermatophagoides spp./grass pollen or Dermatophagoides pteronyssinus/grass pollen extracts. Rhinoconjunctivitis and asthma symptom and medication scores were assessed annually for up to five years using mixed models for repeated measures and complementary non-parametric analyses; adverse reactions were also recorded. The two treatment cohorts included 105 and 137 patients, respectively. Both formulations were associated with significant reductions in rhinoconjunctivitis and asthma-related scores from the first year of treatment. For the Dermatophagoides spp./grass pollen formulation, the Rhinoconjunctivitis Combined Symptom and Medication Score (RCSMS) and Asthma Combined Symptom and Medication Score (ACSMS) least-squares means decreased by 47.3% and 41.9% at T1 and by 53.0% and 55.1% at T2, respectively. For Dermatophagoides pteronyssinus/grass pollen, reductions at T1 were 51.6% and 58.7%, with improvements generally maintained during follow-up. Adverse reactions were infrequent and predominantly local; two systemic reactions occurred in the Dermatophagoides spp./grass pollen cohort. These findings suggest that, in selected patients treated under routine clinical practice conditions, both formulations were associated with reductions in symptom and medication scores and showed an acceptable safety profile. However, due to the retrospective uncontrolled design, these reductions cannot be attributed solely to immunotherapy, and prospective controlled studies are needed to confirm these observations.