Rhinitis, sinusitis, and upper airway disease
Long-lasting effects of sublingual immunotherapy according to its duration: A 15-year prospective study

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Background

Data on the long-term effects of sublingual immunotherapy (SLIT) are sparse, and the optimal duration of treatment is a matter of debate.

Objective

We sought to prospectively evaluate the long-term effect of SLIT given for 3, 4, or 5 years and to compare the effect of those different durations.

Methods

In this prospective open controlled study we followed up patients with respiratory allergy who were monosensitized to mites for 15 years. The subjects were divided in 4 groups receiving drug therapy alone or SLIT for 3, 4, or 5 years. Clinical scores, skin sensitizations, methacholine reactivity, and nasal eosinophil counts were evaluated every year during the winter months. The clinical effect was considered to persist until clinical scores remained at less than 50% of the baseline value, and then patients underwent another course of SLIT.

Results

Seventy-eight patients were enrolled, and 59 completed the study. In the 12 control subjects no relevant change in clinical scores was seen throughout the study. In the patients receiving SLIT for 3 years, the clinical benefit persisted for 7 years. In those receiving immunotherapy for 4 or 5 years, the clinical benefit persisted for 8 years. New sensitizations occurred in all the control subjects over 15 years and in less than a quarter of the patients receiving SLIT (21%, 12%, and 11%, respectively). The second course of vaccination induced a benefit more rapidly than the first course. The behavior of bronchial hyperreactivity and nasal eosinophils paralleled the clinical score.

Conclusion

Under the present conditions, it can be suggested that a 4-year duration of SLIT is the optimal choice because it induces a long-lasting clinical improvement similar to that seen with a 5-year course and greater than that of a 3-year vaccination.

Section snippets

Study design

For more data on study design, see Fig 1. We performed a prospective, open, controlled, 4-parallel-group, partially randomized study involving patients with allergic rhinitis and bronchial hyperreactivity with or without overt asthma solely because of mites. After a baseline evaluation, patients were assigned to the control group (drugs only) or to the SLIT group (SLIT plus drugs). This assignment was made according to patients’ preferences. Patients receiving SLIT were then randomized

Patients

During the screening phase, 198 patients who met the inclusion criteria were identified. Of them, 78 patients (44 male and 34 female patients with a mean age of 22.2 ± 5.2 years) agreed to participate in the study and entered the baseline evaluation from September 1992 to February 1993. Twenty-one patients refused SLIT, received pharmacotherapy alone, and therefore represented the control group. The remaining 57 patients were prescribed SLIT in addition to drugs and were subsequently randomized

Discussion

The most important distinguishing feature between drug therapy and specific immunotherapy is that the latter can profoundly modify the immune response to allergens. In fact, in the last years, it has been shown that the mechanism of action involves numerous components of the immune response, such as regulatory T cells, IgG4 “blocking” antibodies, and TH cell subsets.5 Some of those effects have been recently confirmed also for SLIT.15, 16, 17, 18 The main clinical implication of the mechanisms

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  • Cited by (0)

    Supported in part by ARMIA (Associazione Ricerca Malattie Immunologiche e Allergiche).

    Disclosure of potential conflict of interest: I. Spadolini is employed by Anallergo. The rest of the authors have declared that they have no conflict of interest.

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