Olfactory dysfunction in Japanese children with moderate-to-severe allergic rhinitis.

Objective: Detailed quantitative studies on olfaction remain inadequate in patients with paediatric allergic rhinitis (AR). This study examined olfactory dysfunction in children with AR.

Methods: From July 2016 to November 2018, children aged 6-9 years were recruited and grouped as AR (n = 30) or without AR (control group, n = 10). Odour identification was evaluated by the Universal Sniff (U-Sniff) test and the Open Essence (OE). The results were compared between the AR and control groups. Intranasal mucosa findings, nasal smear eosinophil counts, blood eosinophil counts, total immunoglobulin E (IgE) levels, Japanese cedar-specific IgE and Dermatophagoides pteronyssinus-specific IgE were evaluated in all participants. Additionally, the presence of sinusitis and adenoid hypertrophy in patients with AR was also evaluated by sinus X-ray examinations.

Results: The median U-Sniff test scores were not significantly different between the AR and control groups (9.0 vs. 10.0, respectively; p = 0.107). The OE score was significantly lower in the AR group than in the control group (4.0 vs. 8.0; p = 0.007, respectively), especially in the moderate-to-severe AR group versus the control group (4.0 vs. 8.0; p = 0.004). Furthermore, in the OE, the correct answer rates for 'wood', 'cooking gas' and 'sweaty socks' were significantly lower in the AR group than in the control group.

Conclusions: Paediatric AR patients can reduce olfactory identification ability, and the degree may be associated with the severity of AR in nasal mucosal findings. Furthermore, olfactory dysfunction may slow down the response to 'emergency situations', such as gas leak.