Early Aeroallergen Sensitization Is Associated with Higher Fractional Exhaled Nitric Oxide Levels in School Age Children Independent of Asthma Diagnosis

RationaleAllergic sensitization in childhood is associated with elevated fractional exhaled nitric oxide (FeNO). Whether the timing of sensitization alters this relationship is unclear.MethodsChildren at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively in the Childhood Origins of Asthma (COAST) study. FeNO was measured yearly by an online technique from ages 5 through 11 years. The presence of aeroallergen sensitization was determined annually utilizing ImmunoCAP testing. Subjects were classified as having developed early sensitization (age 1-2 years), later sensitization (age 3-11 years), or no sensitization. Asthma was defined using a previously described clinical definition.ResultsChildren who were sensitized early had higher FeNO levels at age 11 years (mean 22.6 ppb, 95% CI 18.8-27.2) than children who were sensitized later (15.5 ppb, 95% CI 13.4-18.0; p=0.006) or never sensitized (9.5 ppb, 95% CI 8.2-10.9, p<0.0001). Higher FeNO levels were significantly associated with a diagnosis of asthma at age 11 (p=0.004); however, only among sensitized children. There was no significant difference in FeNO between sensitized children with or without asthma at age 11 [mean 19.9 ppb (95% CI 16.3-24.2) vs. 16.9 ppb (95% CI 14.2-20.1); p=0.22].ConclusionsAge at aeroallergen sensitization was inversely related to subsequent FeNO. These findings suggest that early aeroallergen sensitization is related to increased airway inflammation in school-age children. RationaleAllergic sensitization in childhood is associated with elevated fractional exhaled nitric oxide (FeNO). Whether the timing of sensitization alters this relationship is unclear. Allergic sensitization in childhood is associated with elevated fractional exhaled nitric oxide (FeNO). Whether the timing of sensitization alters this relationship is unclear. MethodsChildren at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively in the Childhood Origins of Asthma (COAST) study. FeNO was measured yearly by an online technique from ages 5 through 11 years. The presence of aeroallergen sensitization was determined annually utilizing ImmunoCAP testing. Subjects were classified as having developed early sensitization (age 1-2 years), later sensitization (age 3-11 years), or no sensitization. Asthma was defined using a previously described clinical definition. Children at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively in the Childhood Origins of Asthma (COAST) study. FeNO was measured yearly by an online technique from ages 5 through 11 years. The presence of aeroallergen sensitization was determined annually utilizing ImmunoCAP testing. Subjects were classified as having developed early sensitization (age 1-2 years), later sensitization (age 3-11 years), or no sensitization. Asthma was defined using a previously described clinical definition. ResultsChildren who were sensitized early had higher FeNO levels at age 11 years (mean 22.6 ppb, 95% CI 18.8-27.2) than children who were sensitized later (15.5 ppb, 95% CI 13.4-18.0; p=0.006) or never sensitized (9.5 ppb, 95% CI 8.2-10.9, p<0.0001). Higher FeNO levels were significantly associated with a diagnosis of asthma at age 11 (p=0.004); however, only among sensitized children. There was no significant difference in FeNO between sensitized children with or without asthma at age 11 [mean 19.9 ppb (95% CI 16.3-24.2) vs. 16.9 ppb (95% CI 14.2-20.1); p=0.22]. Children who were sensitized early had higher FeNO levels at age 11 years (mean 22.6 ppb, 95% CI 18.8-27.2) than children who were sensitized later (15.5 ppb, 95% CI 13.4-18.0; p=0.006) or never sensitized (9.5 ppb, 95% CI 8.2-10.9, p<0.0001). Higher FeNO levels were significantly associated with a diagnosis of asthma at age 11 (p=0.004); however, only among sensitized children. There was no significant difference in FeNO between sensitized children with or without asthma at age 11 [mean 19.9 ppb (95% CI 16.3-24.2) vs. 16.9 ppb (95% CI 14.2-20.1); p=0.22]. ConclusionsAge at aeroallergen sensitization was inversely related to subsequent FeNO. These findings suggest that early aeroallergen sensitization is related to increased airway inflammation in school-age children. Age at aeroallergen sensitization was inversely related to subsequent FeNO. These findings suggest that early aeroallergen sensitization is related to increased airway inflammation in school-age children.