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

https://doi.org/10.1016/j.anai.2012.07.015Get rights and content

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.

Introduction

Allergen specific immunotherapy (SIT) is the only treatment of allergy modifying the immune response.[1], [2] Immunotherapy alleviates the symptoms, prevents the onset of new sensitizations, and reduces the risk of developing asthma. Moreover, its clinical efficacy lasts many years.3

An adequate SIT treatment should ideally produce a long-term therapeutic benefit after its completion. The results obtained in some trials suggest that the duration of the treatment might influence the duration of the clinical effect after completion of SIT.[4], [5], [6] The recommended duration of SIT treatment relies on empiric data and is not well documented. To our knowledge, there are only 2 trials that prospectively explore the currently recommended duration limits of SIT,[7], [8] but the long-term efficacy of SIT was not assessed in these studies. However, no publications have compared how the duration of SIT might influence the long-term efficacy of immunotherapy.

Our objective was to compare the long-term efficacy of 3 and 5 years of house dust mite (HDM) SIT in children with asthma. Efficacy was assessed on the basis of a steroid-sparing effect, asthma symptoms score, lung function, asthma remission, methacholine challenge, and the Paediatric Asthma Quality of Life Questionnaire (PAQLQ).

Section snippets

Patients

Ninety boys and girls with IgE-dependent asthma caused by sensitization only to HDMs (Dermatophagoides farinae [n = 5] or Dermatophagoides pteronyssinus [n = 7] or both [n = 78]) were randomly selected (computer-generated allocation schedule) from an outpatient population at our allergy clinic center who fulfilled the inclusion criteria (n = 180 potential study candidates). We included patients who completed a 3-year course of SIT (SIT3 group, n = 30), those who completed a 5-year course of SIT

Patients

Eighty-four children completed the study; only 6 (7%) dropped out, all from the SIT5 group. In all cases, the reason for dropping out was lost to follow-up (family moved or family changed health care provider): 2 patients in the first year of the prospective phase and 4 patients during the second year. Baseline characteristics of the patients who completed the study are listed in Table 1. The minimal ICS dose controlling the symptoms at the beginning of the retrospective phase of the study was

Discussion

To our knowledge, this is the first trial that prospectively explores the long-term effect of different durations of SIT after its discontinuation. Current immunotherapy guidelines[16], [17] suggest that SIT should be discontinued on an individual basis; the usual duration ranges from 3 to 5 years. Data suggest that SIT administration is effective in the treatment of respiratory allergy, and its efficacy continues after treatment discontinuation.[18], [19] However, trials specifically designed

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    Disclosures: Authors have nothing to disclose.

    Funding Sources: This study was funded by grant 503/2-056-01 from the Medical University of Lodz, Lodz, Poland.

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