Obstructive phenotype as a predictor of asthma control and stability in children

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Conference Proceeding

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Publication Title

Am J Respir Crit Care Med


RATIONALE Airway obstruction may be partitioned into two components: Reduced caliber, causing a decrease in airflow (airflow limitation); and airway closure, causing a cessation of airflow (air-trapping). The airway closure component has been associated with asthma severity and asthma instability in both adults and children, but the most commonly used measures of obstruction, FEV1 and FEV1/FVC, do not discriminate the airway closure component. Other measures of peripheral airway dysfunction and airway closure are not widely employed for routine clinical assessment of asthma. We hypothesized that routine spirometric variables also could be used to define an air-trapping phenotype in children with asthma, which would identify an increased risk for asthma instability. METHODS We analyzed data from the NIH/NIAID Inner-City Asthma Consortium study, Asthma Phenotypes in Inner-City Children. Pre-and post-bronchodilator (BD) spirometry obtained at the last visit of the 12-month study of children ages 6-17 were used for phenotype analysis. 560 complete spirometric records meeting ATS acceptability criteria were available. We used FVC as the spirometric indicator of air-trapping, reasoning that VC changes are equal and opposite to RV changes when TLC is stable. Definitions: Air-trapping (ATrpg)-Pre-BD FVC



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