Background Rhinitis is a common problem in children. Airway nitric oxide (NO) was proposed to represent eosinophilic inflammation. Objectives To evaluate airway NO level in children with house dust mite (HDM)-induced allergic rhinitis Methods Children aged 5 to 18 years old with moderate–severe persistent rhinitis and positive result for the HDM nasal provocation test (NPT) was enrolled. The nasal symptoms evaluated by total nasal symptom score (TNSS) and visual analog scale (VAS) were recorded. Skin prick test (SPT) to common aeroallergens, fractional exhaled nitric oxide (FeNO), nasal nitric oxide (nNO), and blood test for specific IgE (sIgE) to HDM was measured. Rhinitis severity was categorized as severe if the VAS score > 7. Results Forty-eight children with HDM-induced allergic rhinitis with the mean age of 9.3 ± 2.4 years were enrolled. nNO levels and VAS score were significantly correlated (R = 0.398, P = .005). Children with severe rhinitis had significantly higher nNO levels than moderate rhinitis (1652.05 vs 941.30 parts per billion [ppb], P = .002), while there was no difference in FeNO level. ROC curve analysis demonstrated the cut-off value of nNO at 1350 ppb (AUC 0.764, 95% CI: 0.616-0.911, P = .002) for detecting severe HDM-induced allergic rhinitis with the sensitivity of 78% and the specificity of 71%. The level of FeNO in children who had HDM mean wheal diameter (MWD) > 8 mm was significantly higher than those with HDM MWD of 3 to 8 mm and those with a negative test (39.7 vs 14.3 vs 14.4 ppb; P = .006, respectively). Children who had sIgE to HDM < 0.35 KUA/L had significantly lower FeNO than those with sIgE to HDM 0.35 to 50 KUA/L and >50 KUA/L (9.5 vs 19.7 vs 40.4 ppb; P = .029, respectively). Conclusions Cut-off value for the diagnosis of severe HDM-induced chronic rhinitis was proposed. Rhinitis children who had a higher degree of HDM sensitization had a higher level of FeNO.

Cat allergy has been reported 10-20% of the population.Here, we sought to study the current prevalence and risk factors of catinduced allergic rhinitis (AR) and local allergic rhinitis (LAR) in children. METHODS: Chronic and frequent rhinitis children aged 5-18 years old were enrolled. The demographic data, total nasal symptom scores (TNSS), and visual analog scales (VAS) were recorded. Skin prick test, serum specific IgE to cat allergen, and cat allergen nasal provocation test (NPT) were performed. RESULTS: Sixty-one children were enrolled with the mean age 9.0763.93 years, 59% were male. The mean TNSS and VAS were 2.5461.89 and 3.5062.05, respectively. Of 48 (78.7%) children with positive SPT to any aeroallergens, 14 (29.2%) children were positive SPT to cat. Of all children with positive SPT to cat, 13 (92.9%) children were positive specific IgE to cat. Children who were negative to SPT and serum specific IgE to cat, 14 (29.8%) children were positive NPT to cat and were diagnosed with LAR. The prevalence of cat-induced AR and LAR were 23%. No differences were obtained in SPT size, specific IgE level, and cat NPT positivity between cat owners and non-owners. 64.3% of children with cat-induced AR were positive to the lowest dose of cat NPT (500 BAU/ml), while the patients with LAR to cat allergen were almost positive to cat NPT at higher concentration. CONCLUSIONS: The prevalence of AR and LAR to cat have been increasing compared with previous reports. Cat-induced AR patients seem to have NPT positivity at lower concentration compared to LAR.

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