Characteristics That Distinguish Difficult-to-Control Asthma in Inner-City Children
Saturday, March 5, 2016
South Exhibit Hall H (Convention Center)
Jacqueline A. Pongracic, MD FAAAAI, Rebecca A. Zabel, MS, Denise C. Babineau, PhD, Edward M. Zoratti, MD, FAAAAI, George T. O'Connor, MD, Robert A. Wood, MD FAAAAI, Gurjit K. Khurana Hershey, MD PhD FAAAAI, Carolyn Kercsmar, MD, Rebecca S. Gruchalla, MD PhD FAAAAI, Meyer Kattan, MD, Stephen J. Teach, MD, Samuel J. Arbes Jr., William W. Busse, MD FAAAAI, Peter J. Gergen, MD MPH, Alkis Togias, MD FAAAAI, Cynthia Visness, PhD MPH, Andrew H Liu, MD FAAAAI
Rationale: Because a significant proportion of inner-city children are only partially responsive to guidelines-directed asthma therapy, we sought to identify the clinical characteristics that distinguish difficult-to-control asthma.

Methods: The Inner City Asthma Consortium enrolled children aged 6-17 years with asthma.  After baseline assessment, participants had bi-monthly guidelines-based asthma management visits over one year.  Difficult-to-control asthma (DCA) versus Easy-to-control asthma (ECA) were defined as daily controller therapy with inhaled fluticasone >500mcg +/-LABA versus <100mcg assigned on at least 4 visits, respectively. Forty-one baseline variables were used to compare DCA and ECA using univariate analyses.  A variable selection algorithm was used to determine the most relevant features of DCA versus ECA. Generalized additive mixed-effects models were used to describe seasonal variation of symptoms, lung function, and exacerbations.

Results: Of the 619 participants, 40.9% had DCA and 37.5% had ECA. DCA was characterized by persistently low lung function, more frequent exacerbations in the spring and fall as well as greater daytime and nocturnal symptoms in the fall and winter. Of the 41 variables, FEV1 bronchodilator reversibility (BDR) was the most important characteristic distinguishing DCA.  The other dominant features of DCA, in order of importance, included: FEV1/FVC ratio, rhinitis medication score, FEV1 % predicted, rhinitis symptom score, mold sensitization, and total serum IgE.

Conclusions: The phenotypic characteristics of DCA in inner-city children include seasonal loss of asthma control, BDR, persistently low lung function, rhinitis severity and atopy. These findings suggest that baseline assessment of BDR and allergy-related factors, including rhinitis, may predict future DCA.