Children With Food Allergy Are at Risk of Lower Lung Function on High-Pollen Days

Background Grass pollen exposure is a risk factor for childhood asthma hospital attendances. However, its short-term influence on lung function, especially among those with other allergic conditions, has been less well-studied. Objective To investigate this association in a population-based sample of children. Methods Within the HealthNuts cohort, 641 children performed spirometry during the grass pollen season. Grass pollen concentration was considered on the day of testing (lag 0), up to 3 days before (lag 1–lag 3), and cumulatively (lag 0–3). We used linear regression to assess the relevant associations and examined potential interactions with current asthma, hay fever or eczema, and food allergy. Results Associations were observed only in children with allergic disease (P value for interaction ≤ 0.1). In children with food allergy, grass pollen concentration was associated with a lower ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) and lower mid-forced expiratory flows (FEF25%–75%) at all lags (eg, at lag 2, FEV1/FVC z-score = –0.50 [95% CI –0.80 to –0.20] and FEF25%–-75% z-score = –0.40 [–0.60 to –0.04] per 20 grains/m3 pollen increase), and increased bronchodilator responsiveness (BDR) at lag 2 and lag 3 (eg, at lag 2, BDR = (31 [95% CI –0.005 to 62] mL). In children with current asthma, increasing grass pollen concentration was associated with lower FEF25%–75% and increased BDR, whereas children with current hay fever or eczema had increased BDR only. Conclusions A proactive approach needs to be enforced to manage susceptible children, especially those with food allergy, before high–grass pollen days. Grass pollen exposure is a risk factor for childhood asthma hospital attendances. However, its short-term influence on lung function, especially among those with other allergic conditions, has been less well-studied. To investigate this association in a population-based sample of children. Within the HealthNuts cohort, 641 children performed spirometry during the grass pollen season. Grass pollen concentration was considered on the day of testing (lag 0), up to 3 days before (lag 1–lag 3), and cumulatively (lag 0–3). We used linear regression to assess the relevant associations and examined potential interactions with current asthma, hay fever or eczema, and food allergy. Associations were observed only in children with allergic disease (P value for interaction ≤ 0.1). In children with food allergy, grass pollen concentration was associated with a lower ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) and lower mid-forced expiratory flows (FEF25%–75%) at all lags (eg, at lag 2, FEV1/FVC z-score = –0.50 [95% CI –0.80 to –0.20] and FEF25%–-75% z-score = –0.40 [–0.60 to –0.04] per 20 grains/m3 pollen increase), and increased bronchodilator responsiveness (BDR) at lag 2 and lag 3 (eg, at lag 2, BDR = (31 [95% CI –0.005 to 62] mL). In children with current asthma, increasing grass pollen concentration was associated with lower FEF25%–75% and increased BDR, whereas children with current hay fever or eczema had increased BDR only. A proactive approach needs to be enforced to manage susceptible children, especially those with food allergy, before high–grass pollen days.