Distinguishing characteristics of difficult-to-control asthma in inner-city children and adolescents

Pongracic, J. A.; Krouse, R. Z.; Babineau, D. C.; Zoratti, E. M.; Cohen, R. T.; Wood, R. A.; Khurana Hershey, G. K.; Kercsmar, C. M.; Gruchalla, R. S.; Kattan, M.; Teach, S. J.; Johnson, C. C.; Bacharier, L. B.; Gern, J. E.; Sigelman, S. M.; Gergen, P. J.; Togias, A.; Visness, C. M.; Busse, W. W.; Liu, A. H.

J Allergy Clin Immunol. 2016 Oct 11; 138(4):1030-1041

Abstract

BACKGROUND: Treatment levels required to control asthma vary greatly across a population with asthma. The factors that contribute to variability in treatment requirements of inner-city children have not been fully elucidated. OBJECTIVE: We sought to identify the clinical characteristics that distinguish difficult-to-control asthma from easy-to-control asthma. METHODS: Asthmatic children aged 6 to 17 years underwent baseline assessment and bimonthly guideline-based management visits over 1 year. Difficult-to-control and easy-to-control asthma were defined as daily therapy with 500 mug of fluticasone or greater with or without a long-acting beta-agonist versus 100 mug or less assigned on at least 4 visits. Forty-four baseline variables were used to compare the 2 groups by using univariate analyses and to identify the most relevant features of difficult-to-control asthma by using a variable selection algorithm. Nonlinear seasonal variation in longitudinal measures (symptoms, pulmonary physiology, and exacerbations) was examined by using generalized additive mixed-effects models. RESULTS: Among 619 recruited participants, 40.9% had difficult-to-control asthma, 37.5% had easy-to-control asthma, and 21.6% fell into neither group. At baseline, FEV1 bronchodilator responsiveness was the most important characteristic distinguishing difficult-to-control asthma from easy-to-control asthma. Markers of rhinitis severity and atopy were among the other major discriminating features. Over time, difficult-to-control asthma was characterized by high exacerbation rates, particularly in spring and fall; greater daytime and nighttime symptoms, especially in fall and winter; and compromised pulmonary physiology despite ongoing high-dose controller therapy. CONCLUSIONS: Despite good adherence, difficult-to-control asthma showed little improvement in symptoms, exacerbations, or pulmonary physiology over the year. In addition to pulmonary physiology measures, rhinitis severity and atopy were associated with high-dose asthma controller therapy requirement.

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