Safety of Subcutaneous Specific Immunotherapy with Pollen Allergen Extracts for Respiratory Allergy

BACKGROUND: Specific immunotherapy (SIT) is a well-documented treatment for respiratory allergy. However, the major risk of SIT is the development of systemic anaphylactic reactions. OBJECTIVES: To evaluate the safety of SIT given by subcutaneous route for 3 years to patients with seasonal allergic rhinitis (AR) with or without asthma. METHODS: A prospective open-label study of immunotherapy (Chenopodium album, Bermuda grass, or both) in 181 consecutive patients with AR with or without asthma. After an initial dose-escalation phase, a maintenance dose of 0.5 ml of 100,000 PNU/ml was administered monthly for 3 years. The occurrence and severity of systemic reaction (SR) and local reaction was recorded and graded according to the WHO position paper. RESULTS: Of 181 patients enrolled, 57 (31%) did not complete the study (53 due to poor compliance and 4 due to systemic side effects). All 4 patients who developed SR had asthma and all the SR occurred during the dose- escalation phase. Three patients had moderate SR (grade 2), while 1 patient had severe reaction (grade 3). Three of the SR occurred within the first 20 min after injection and 1 SR occurred 2 h after injection. None of the reactions were life threatening and were managed easily. Total rhinitis symptom score decreased from 11.8 at baseline to 7.46 at the end of treatment (p<0.001). The size of the skin prick test reaction to the main sensitising allergen was reduced from 7.48 +/- 2.26 mm at baseline to 5.60 +/- 2.18 mm at the end of treatment, p<001. CONCLUSION: If a strict protocol is used, SIT is safe in AR patients with or without mild asthma and may result in significant subjective and objective improvement.