Immunotherapy
Allergen immunotherapy (AIT), either in the subcutaneous (SCIT) or sublingual (SLIT) form, has long been shown to result in improved AR control in all age groups and aspires to be the only etiologic treatment for respiratory allergies (allergic rhinitis (AR) and asthma) through induction of immunologic tolerance [126] [127]. Pooled analyses support the complementary use of AIT on pharmacotherapy in AR patients moreover due to achievement of long-lasting therapeutic effect [128]. Recently, data from a real-world study confirmed the medication sparing effect and long-term symptom relief following AIT, in a cohort of grass AR patients, including children. In agreement, subcutaneous allergoid immunotherapy in house dust mite AR children resulted in significant reduction in AR and asthma medication, even after long-term cessation of AIT [129].
Early-onset asthma is largely associated with IgE sensitization and AR [130], thus AIT has long been suggested as a disease modifying strategy potentially preventing allergen sensitization and asthma occurrence in children with AR [131]. Although early clinical studies showed a preventive effect of AIT on the occurrence of new sensitizations in children with rhinitis [132], this is still inconclusive [133]. A recent meta-analysis identified a short term preventive effect of AIT on novel sensitization development; nevertheless, the included studies were highly heterogenous [134]. Nevertheless, the preventive effects of AIT on asthma development and progression has been confirmed in real-world studies, assessing the effect of SLIT immunotherapy in grass pollen subjects with AR [135]. Moreover, a long-term randomized controlled trial, the Grazax Asthma Prevention (GAP) study, [136], showed significantly lower and long-lasting incidence of asthma following 3-year AIT in grass AR subjects, while significant lower levels of total and allergen specific IgE and reductions in skin prick test response to grass were noted [137].