Prevalence of possible undiagnosed asthma and associated morbidity among urban schoolchildren.

OBJECTIVE: The extent to which urban children endure the symptoms and consequences of asthma without a physician diagnosis has not been well studied. Our objective was to obtain an estimate of the prevalence of possible undiagnosed asthma in a population of urban schoolchildren. DESIGN AND METHODS: A population-based cross-sectional study was conducted in urban schoolchildren, grades 3 to 5. Undiagnosed asthma was defined as caretaker report of symptoms and/or bronchial hyperresponsiveness, defined as a 15% or greater drop in baseline forced expiratory volume in 1 second, after exercise challenge.
RESULTS: A total of 230 children (61% of those eligible) participated in the study. Forty children (17.4%; 95% Confidence interval (CI) = 12.5% to 22.3%) had reports of a physician diagnosis of asthma. Of these, 33 (14.3%; (95% CI = 9.8% to 18.9%) reported wheezing in the past 12 months. Among the remaining 189 eligible children, 11 (5.8%; 95% CI = 2.5% to 9.2%) met study criteria for undiagnosed asthma based on bronchial hyperresponsiveness (BHR). Another 16 (8.5%; 95% CI = 4.5% to 12.4%) met study criteria for undiagnosed asthma through modified American Thoracic Society symptom criteria. Overall, 27 children (27/189; 14.3%) fulfilled criteria for undiagnosed asthma. Children identified as having undiagnosed asthma were compared with children who had no BHR and no symptoms and who did not report a physician diagnosis of asthma (children without asthma). Children with BHR were more likely to have a report of allergies and eczema than children without asthma, odds ratios (OR) = 8.5 (95% CI = 2.4 to 30.7) and 6.4 (95% CI = 1.1 to 38.1), respectively. Children meeting symptom criteria were more likely to have a report of allergies, OR = 6.2 (95% CI = 2.0 to 19.1), and bronchitis, OR = 6.7 (95% CI = 2.0 to 22.4), and were also more likely to report sleep disruption, OR = 7.1 (95% CI = 2.3 to 21.8) and missed physical education classes, OR = 15.0 (95% CI = 4.8 to 46.7), compared with children without asthma.
CONCLUSIONS: We estimated a prevalence of 14.3% for possible undiagnosed asthma among urban schoolchildren, grades 3 to 5, through caretaker report of symptoms or BHR postexercise challenge. Children with undiagnosed asthma reported more atopic disease than children without asthma. In addition, children meeting symptom criteria for asthma reported more bronchitis, sleep disruption, and missed physical education classes than did those without asthma. These results suggest that rates of undiagnosed asthma may be high in this predominantly black school-age population.