Comparison of the long-term efficacy of 3- and 5-year house dust mite allergen immunotherapy

Abstract

Background: The recommended duration of specific immunotherapy (SIT) treatment relies on empiric data and is not well documented.

Objective: To detect possible differences in the long-term effectiveness between 3 and 5 years of house dust mite (HDM) SIT in asthmatic children.

Methods: We performed a 3-year natural history study of 90 asthmatic children who were sensitive only to HDM. Three groups were recruited: 30 who had completed 3 years of HDM SIT (SIT3), 30 who had completed 5 years of HDM SIT (SIT5), and 30 who had an indication for HDM SIT but whose parents refused HDM SIT. Patients attended an enrollment visit in 2007, after SIT discontinuation, and 3 annual follow-up visits at the clinic. The long-term effectiveness of HDM SIT was primarily assessed via analysis of the reduction in required inhaled corticosteroid dose, forced expiratory volume in 1 second, and asthma remission.

Results: A total of 84 children completed the study. Both SIT durations produced excellent results; asthma remission in both SIT3 (50%) and SIT5 (54%) groups was significantly higher when compared with control (3.3%). The minimal controlling inhaled corticosteroid dose reduction in SIT5 group (median, 75%) was significantly higher compared with the SIT3 group (median, 50%) after immunotherapy discontinuation; after 3 years without SIT, no differences were found between the SIT5 and SIT3 groups (median, 100% and 94%, respectively). We observed a slightly higher increase in forced expiratory volume in 1 second in the SIT5 group compared with the SIT3 group.

Conclusion: Three years of SIT is an adequate duration for the treatment of childhood asthma associated with HDM allergy because 2 further years of SIT added no clinical benefit.