Allergen-specific immunotherapy is the only treatment that alters the natural course of allergic rhinitis and prevents allergies by inducing immunotolerance.
Research has shown that in certain countries, allergic rhinitis (AR) has a 50% incidence. Although subcutaneous immunotherapy (SCIT) has proven effective as a treatment, particularly for house dust mite (HDM)-induced AR, few studies have explored the long-term efficacy of this treatment pathway and its varied outcomes for both adults and children.
To address this knowledge gap, Yuan Zhang, MD, and colleagues developed an open-design, observational, long-term, clinical follow-up study that examined both adults and children who have received a cluster regimen of HDM-SCIT. A cluster regimen decreases the dose-escalation phase from 14 to 6 weeks, according to the researchers.
The findings were published in Allergy, Asthma & Clinical Immunology, in which Dr. Zhang and colleagues wrote, “HDM-induced AR is associated with a higher risk for asthma, the prevalence of which is increasing in many countries, especially among children. Allergen-specific immunotherapy [AIT] is the only treatment that alters the natural course of AR and prevents asthma and other allergies by inducing immunotolerance.”
For this reason, the study authors noted, confirmation of long-term efficacy is needed.
Both Monosensitized & Polysensitized Patients Enrolled
Researchers identified patients between the ages of 5 and 60 with a history of HDM-induced AR for at least 2 years. Patients both monosensitized and polysensitized were included in the study; those excluded had uncontrolled asthma, immunologic/systemic diseases, malignant tumors, and other conditions for which AIT is contraindicated Participants were treated with SCIT for 3 years and followed for at least 3 years after therapy. Of the 598 participants who were initially identified, 161 completed the study (adult group, N=103; pediatric group, N=58).
Total nasal symptom score (TNSS) served as the primary efficacy endpoint, which quantified nasal symptoms such as nasal blockage, runny nose, sneezing, and itchy nose. Secondary endpoints were total ocular symptom score (TOSS), medication score (MS), combined symptom-medication score (CSMS), and the mini-rhinoconjunctivitis QOL questionnaire (RQLQmini).
No Fatal Reactions to SCIT Treatment Observed
Compared with the adult group, the baseline efficacy parameters were much lower in the pediatric group (Figure). From baseline to the 3-year follow-up, the adult group showed more significant improvement in TNSS, TOSS, and CSMS after SCIT compared with the pediatric group (median interquartile range; TNSS: 4.00 [1.00-8.00] vs 3.00 [−2.00 to 6.00]; P=0.005; TOSS: 1.00 [0.00-3.00] vs 1.00 [−1.00 to 2.00]; CSMS: 1.50 [0.50-2.67] vs 1.00 [−0.21 to 2.17]; P=0.024). However, in the extended follow-up (up to 13 years) of the pediatric group, TNSS, MS, CSMS, and RQLQmini scores were found to be significantly lower than the prior scores captured at baseline.
Furthermore, 86.4% of pediatric group participants initially classified as non-responders to SCIT achieved improvement in TNSS during the extended follow-up period. In the adult group, 39.1% of non-responders achieved relatively lower TNSS during the extended follow-up period.
In terms of safety, no fatal reactions to SCIT treatment were observed. In the pediatric group, one grade 3 and six grade 1 systemic adverse reactions (SADRs) were reported; in the adult group, three grade 1 SADRs were reported (1.26% vs 0.68% of injections; P=0.043). The improvement of TNSS scores and the long-term efficacy of SCIT were unrelated to SADRs and local ADRs.
“This is the first study to report that TNSS may continuously improve beyond immunotherapy termination in children who complete a 3-year SCIT during childhood,” Dr. Zhang and colleagues wrote.
