Table 2.

Studies on the long-term effect and preventive role of SLIT in allergic children.

Author, Year	Type of Study	Aim of the Study	Allergen Extract	Patients’ Age (y)	Population (Total Patients, Active/Control Groups)	AIT Duration (Months)	Main Results
Novembre et al., 2004 [73]	RCT	Determine whether SLIT is effective in reducing ocular and nasal symptoms and the development of asthma in allergic children	Grass pollen	5–14	113 (54/59)	4	SLIT ↓ seasonal allergic rhinitis symptoms and ↓ the development of seasonal asthma
Marogna et al., 2008 [74]	RCT	Evaluate the clinical and preventive effects of SLIT in allergic children	Grass pollen	5–17	216 (144/72)	36	SLIT reduced the onset of new sensitizations and mild persistent asthma and ↓ bronchial hyperreactivity
Valovirta et al., 2018 [75]	RDBPC	Investigate the effect of grass SLIT on the risk of developing asthma	Grass pollen	5–12	812 (398/414)	36	SLIT ↓ the risk of experiencing asthma symptoms or using asthma medication ↓ Total IgE, ↓sIgE and SPT for grass pollen

RCT, randomized controlled study, SPT, skin prick test.