Usefulness of specific immunotherapy in patients with severe perennial allergic rhinitis induced by house dust mite: A double-blind, randomized, placebo-controlled trial

Objectives: To evaluate the effectiveness of specific immunotherapy (SIT) in patients with severe house dust mite (HDM)-induced perennial allergic rhinitis using diary cards and objective endpoints. Patients and Methods: Thirty-six adult patients were selected with moderate to severe allergic rhinitis due to HDM allergy uncontrolled by regular anti-allergic drugs. Twenty-eight patients completed the study, 22 of these patients also had mild asthma. Subjects were stratified for HDM sensitivity on the basis of their 4-week diary card score and the size of their immediate and late-phase skin reaction to HDM. The groups were well matched for all relevant parameters. Patients were randomized to receive active preparation (Alutard®-SQ, ALK, Dermatophagoides pteronyssinus extract) or an identical placebo preparation. Increasing doses were administered until the maintenance dose was reached. This dose was then given once a month for 12 months. Results: Clinical efficacy was evaluated by symptom medication diary cards recorded for 4 weeks after 12 months of continuous treatment and compared with pre-treatment scores. Skin test reactivity was re-measured after 12 months of treatment to HDM, cat dander and codeine phosphate. After 1 year of treatment, the actively treated group showed a 58% reduction in diary card symptom scores (P<0.002) and a 20% reduction in the use of rescue medication. The placebo group had a 32% reduction in symptom scores (P = NS), but no reduction in rescue medication requirements. The active group showed 36% reduction in skin prick test sensitivity to D. pteronyssinus (P = 0.006), while the placebo group values were unchanged. Skin reactivity to codeine was unchanged in both groups. No significant adverse reactions to SIT were encountered. Conclusions: One year of SIT for D. pteronyssinus in patients with poorly controlled rhinitis (± mild asthma) produced clinically useful improvement as shown by symptom-medication diary cards and reductions in immediate skin reactions compared with placebo treatment.