PURPOSE OF THE STUDY.
To determine whether the University of Cincinnati’s Asthma Predictive Index (ucAPI) and/or persistent wheezing by the age of 3 years are able to predict asthma at the age of 7 years, as confirmed by objective measures.
Five hundred eighty-nine children were recruited from the Cincinnati Childhood Allergy and Air Pollution Study, a prospective birth cohort of children with at least 1 atopic parent; 54.8% were boys, 21.2% were African American, and 16.7% were from a household with yearly income <$20 000. Additionally, 53.1% were breastfed until age 4 months, 52.1% attended day care, and 40.8% had at least 1 parent with asthma.
Children were evaluated in the clinic at the ages of 1, 2, 3, 4, and 7 years. A positive ucAPI at age 3 was defined as having ≥2 episodes of wheezing in the previous 12 months at the third-year clinic visit, and 1 of the 3 major criteria (parental asthma, allergic sensitization to ≥1 aeroallergens, or a history of eczema) or 2 of the 3 minor criteria (wheezing without a cold, physician-diagnosed allergic rhinitis, or allergic sensitization to milk or egg). Persistent wheezing at age 3 was defined as ≥2 episodes of wheezing in the previous 12 months at both the second- and third-year clinic visits, or a history of physician-diagnosed asthma in the past 12 months at the third-year clinic visit. Persistent wheezing was further subclassified as allergic (child having at least 1 positive skin prick test to a common aeroallergen) or nonallergic. At age 7, the diagnosis of asthma was confirmed by either an increase in forced expiratory volume in 1 second of ≥12% after bronchodilator therapy or by a positive methacholine challenge test, defined as a provocation concentration causing 20% fall in FEV1 (PC20) <4 mg/mL or by regular use of controller medication in the past 12 months.
One hundred and three children (17.5%) met the asthma definition at age 7 years. At age 3 years, 68 children (12.3%) had a positive ucAPI, and 54 (10.6%) had persistent wheezing, resulting in sensitivities of 44% and 36% and specificities of 94.1% and 95%, respectively. A positive ucAPI at age 3 was associated with a significant risk for objectively confirmed asthma at age 7 (adjusted odds ratio [aOR] 13.3), as was persistent wheezing (aOR 9.8). The atopic persistent wheezing phenotype at age 3 was associated with a higher risk of asthma (aOR 10.4) than the nonatopic persistent wheezing phenotype (aOR 5.4). A household income of <$20 000 per year, sensitization to egg white at age 1 year, and day-care attendance were associated with a higher risk of asthma, and dog ownership was associated with a significantly lower risk for asthma at age 7 years.
ucAPI and persistent wheezing at the age of 3 years are both strong predictors of objectively diagnosed asthma at the age of 7 years with ucAPI having the highest adjusted OR of 13.3. Atopic persistent wheezing at the age of 3 year had a twofold higher odds of confirmed asthma at age 7 years than nonatopic persistent wheezers.
Perhaps the most common question a pediatrician faces when treating a preschool child with wheezing is whether the child will “outgrow” the condition. Diagnosing asthma at an early age remains challenging given the inability to obtain objective measures of lung function. This article provides us with a clinical tool, the ucAPI, to answer this question with reasonable accuracy and guide therapy. The study also confirms the important role that atopic sensitization plays in the development of asthma. The strength of this study is the use of objective measures to confirm the diagnosis of asthma at age 7 years. However, it remains to be seen whether the ucAPI can be applied to children without a family history of atopy.
- Copyright © 2015 by the American Academy of Pediatrics