RESUMEN
<p><b>OBJECTIVE</b>To evaluate the efficacy of SLIT with Dermatophagoides farinae drops in children with allergic rhinitis and allergic asthma according to its different duration.</p><p><b>METHODS</b>The efficacy of Dermatophagoides farinae SLIT in 100 children (aged 3-14 yr) with allergic rhinitis and allergic asthma induced by house dust mites was retrospectively analyzed. All children were treated with Dermatophagoides farinae drops for 4 years and followed-up at the interval of 3 months. Total nasal symptom scores (TNSS), total rhinitis symptomatic medication scores (TRMS), daytime asthma symptom scores (DASS), nighttime asthma symptom scores (NASS), total asthma symptomatic medication scores (TAMS), visual analog scale scores (VAS) and lung function were assessed during follow-up visit. SPSS 20.0 software was used for data analysis.</p><p><b>RESULTS</b>After 2 years' SLIT, compared with 1-year duration, besides NASS (0.00[0.00;0.00], 0.00[0.00;0.00]; Z = 1.811; P > 0.05), TNSS (2.00[1.00;2.00], 0.00[0.00;0.00]; Z = 7.021, P < 0.01), TRMS (2.00[2.00;2.00], 0.00[0.00;0.00]; Z = 8.855; P < 0.01), VAS scores (3.00[2.00;4.00], 1.00[0.00;1.00]; Z = 4.494, P < 0.01), DASS (1.00[0.00;1.00]; 0.00[0.00;0.00]; Z = 4.383, P < 0.01) and TAMS (0.00[0.00;1.00], 0.00[0.00;0.00]; Z = 8.944; P < 0.01) all showed significant improvement. After 3-year duration, compared with 2-year duration, VAS scores (1.00[0.00;1.00], 0.00[0.00;0.00]; Z = 3.645, P < 0.05) in patients were significantly decreased. Other results showed no significant difference. The comparison of efficacy between 3 and 4-year duration showed no significant difference in global clinical outcomes (all P > 0.05).</p><p><b>CONCLUSIONS</b>Patients receiving 2 year' SLIT achieve more clinical benefits than those who receiving 1-year duration. The higher efficacy of 3-year duration compared with 2-year duration is supported by a significant improvement in VAS. Besides, the comparison between 3 and 4-year duration shows no significant difference in global clinical outcomes. Therefore, 3 years' duration is optimal in this study.</p>