The risk of severe rhinoconjunctivitis among school-aged children is significantly increased by comorbid eczema, maternal history of allergic diseases, and exposure to high pollen counts, whereas living with fur-bearing pets during infancy appears to be protective, according to the findings of a nationwide Japanese online survey.1
In undertaking their study, the researchers noted that little is known about factors associated with severity of childhood allergic rhinoconjunctivitis, despite the high prevalence of this disease, its impact on quality of life, and economic burden. They stated in their conclusion, “Further understanding of these risks and protective factors may lead to the discovery of new interventions aimed at managing the disease and improving the quality of life of patients and their caregivers.”1
The research was conducted using an International Study of Asthma and Allergies in Childhood-based questionnaire that was sent to a randomly selected sample of 35,000 families with children aged 6 to 18 years. Parents were asked to complete 1 questionnaire for each child they had within the age range of interest.1
More than 32,000 families responded, and complete questionnaires were available for 26,725 children aged 6 to 12 years. Current rhinoconjunctivitis (within the past 12 months) was reported for 5175 (19.4%) children, and 688 (13.3%) of affected children were identified as having severe symptoms (ie, nasal symptoms interfering with the child’s daily activities “a lot”); 89.1% of children with severe rhinoconjunctivitis had a history of pollinosis.1
Multivariate analyses were performed to assess factors associated with severe rhinoconjunctivitis. Having concurrent eczema was the strongest risk factor (adjusted odds ratio [OR], 1.45) followed by a maternal history of asthma (adjusted OR, 1.34) and a maternal history of allergic rhinitis (OR, 1.30).1 Children living in areas with a high cedar and cypress pollen count (≥3317/mm3), which are the major causes of pollinosis in Japan, were about 20% more likely to have severe rhinoconjunctivitis than their counterparts living in areas with a low count of those pollens (≤1921/mm3). Children living in households with fur-bearing pets during their first year of life had a 30% decreased risk for severe rhinoconjunctivitis relative to children with no furry pets.
In the multivariate analyses, no significant associations were found between severe rhinoconjunctivitis and history of wheeze, sex, birth weight, birth order, mode of birth delivery, breastfeeding, history of food allergy, obesity, maternal history of eczema, parental smoking, or paternal history for any allergic disease.1
The investigators compared their findings with those of 2 other published studies. One involving Spanish children aged 6 to 12 years also reported an association with eczema as well as with conjunctivitis and asthma.2 The other investigation, an Italian study including children aged 4 to 18 years, found rhinoconjunctivitis severity was associated with asthma, oral allergy syndrome, paternal smoking, and having older siblings, but not with paternal or maternal history of allergic diseases.3 The latter study also found that moderate to severe rhinitis was more common among children living in Central and Southern Italy compared with children living in Northern Italy, and the former group was also more often sensitized to pollens. Considering the latter finding and their own results, the Japanese researchers commented that pollens might affect the severity of rhinitis and/or conjunctivitis in many regions of the world.
Yoshida and colleagues acknowledged their survey study had potential limitations that include reliance on parental reports to identify allergic disease and its severity and the inability to account for effects of treatment on disease severity.1 They cited its large sample size and the very high survey response rate as its strengths.
1. Yoshida K, Sasaki M, Adachi Y, et al. Factors associated with the severity of childhood rhinoconjunctivitis. Allergol Int. November 29, 2015. Epub ahead of print.
2. Ibáñez MD, Valero AL, Montoro J, et al. Analysis of comorbidities and therapeutic approach for allergic rhinitis in a pediatric population in Spain. Pediatr Allergy Immunol. 2013;24(7):678-684.
3. Dondi A, Tripodi S, Panetta V, et al; Italian Pediatric Allergy Network (I-PAN). Pollen-induced allergic rhinitis in 1360 Italian children: comorbidities and determinants of severity. Pediatr Allergy Immunol. 2013;24(8):742-751.