Long-term effects of sublingual immunotherapy (SLIT) in preventing the development of asthma in allergic rhinitis: Revision of 15-year follow-up

Background Sublingual immunotherapy (SLIT) has been shown to be effective in controlling the symptoms of allergic rhinitis and asthma, but few studies have assessed its long-term preventive effects on lower-airway inflammation and asthma onset. Objective We sought to evaluate prospectively the long-term effects of SLIT on lower-airway function in patients with allergic rhinitis caused by house dust mites (HDM). Methods We performed a post hoc analysis of a previously published prospective, open-label study involving patients with allergic rhinitis who were monosensitized to mites and followed for 15 years. All participants had bronchial hyperreactivity and were originally assigned to 4 groups receiving either pharmacological therapy alone or SLIT for 3, 4, or 5 years (SLIT 3, SLIT 4, and SLIT 5). Skin sensitization, methacholine reactivity, and respiratory function were evaluated annually during the winter months. Results Seventy-eight patients were enrolled, and 59 completed the study. Over 15 years of observation, new sensitizations occurred in all participants in the control group but in fewer than one-quarter of patients who received SLIT for 3, 4, or 5 years (21%, 12%, and 11%, respectively). Among patients with rhinitis treated only with intranasal corticosteroids and systemic antihistamines, the development of asthma, defined as a decline in FEV to below 80% of the predicted value, was observed in 58% (7 of 12). In contrast, progression to asthma was significantly less frequent among patients with rhinitis treated with SLIT, regardless of treatment duration: 1 of 14 patients in the SLIT 3 group (7%), 1 of 16 in the SLIT 4 group (6%), and 1 of 17 in the SLIT 5 group (6%). Conclusion In the long term, SLIT provided a significant clinical benefit in HDM-induced allergic rhinitis by reducing both the allergic march and asthma onset and by limiting the decline in lung function, as measured by FEV1.