Mixed rhinitis: an underestimated diagnosis in children and adolescents?

Mixed rhinitis (MR) is a potential diagnosis for patients with allergic rhinitis (AR) who present symptoms following exposure to allergens yet also exhibit a significant burden of symptoms after exposure to non-specific irritants. MR is thought to be more prevalent than the isolated form of the disease (AR). However, there are still no established complementary tests or well-defined clinical criteria for diagnosing this phenotype in children and adolescents. This study aimed to propose and evaluate a questionnaire of triggers that could assist in clinically distinguishing patients with MR from those with AR and, through it, to estimate the prevalence of MR in a specialty center. This study focused on patients aged 8 to 18 years diagnosed with AR and under follow-up for at least six months. All patients completed the nasal irritant questionnaire (NIQ) with 18 items. The number of responses with a score ≥ 5 was used to define tertiles. The group from the 3 tertile onwards was described as "high irritant burden" (MR), while the others were defined as "low irritant burden" (AR). Additionally, symptom control scores, allergic sensitization, atopic comorbidities, and indoor exposure to aeroallergens were considered. By using the diagnostic criterion of MR, defined as at least eight positive responses on the NIQ in a patient with AR, it was possible to determine that the prevalence of MR was 42.9% (54/126), with a predominance of males and adolescents (median 13 years) and a mean duration of 3 years since symptom onset. This group also exhibited poorer symptom control. Considering the other evaluated variables, no significant differences were observed between the groups. The prevalence of MR is significant among children with AR, and individuals with MR exhibit poorer symptom control. At least eight positive responses with a score ≥ 5 in the NIQ were a practical cut-off point for differentiating between AR and MR phenotypes.