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Airway hyperresponsiveness to methacholine in 7‐year‐old children: sensitivity and specificity for pediatric allergist‐diagnosed asthma
Author(s) -
Carlsten Chris,
DimichWard Helen,
Ferguson Alexander,
Becker Allan,
DyBuncio Anne,
ChanYeung Moira
Publication year - 2011
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.21347
Subject(s) - medicine , asthma , methacholine , cohort , receiver operating characteristic , pediatrics , bronchial hyperresponsiveness , airway hyperresponsiveness , airway , respiratory disease , surgery , lung
Background: The operating characteristics of PC 20 values used as cut‐offs to define airway hyperresponsiveness, as it informs the diagnosis of asthma in children, are poorly understood. We examine data from a unique cohort to inform this concern. Objective: Determine the sensitivity and specificity of incremental PC 20 cut‐offs for allergist‐diagnosed asthma. Methods: Airway reactivity at age 7 was assessed in children within a birth cohort at high risk for asthma; PC 20 for methacholine was determined by standard technique including interpolation. The diagnosis of asthma was considered by the pediatric allergist without knowledge of the methacholine challenge results. Sensitivity and specificity were calculated using a cross‐tabulation of asthma diagnosis with incremental PC 20 cut‐off values, from 1.0 to 8.0 mg/ml, and plotted as receiver operator characteristic (ROC) curves. The “optimal” cut‐off was defined as that PC 20 conferring maximal value for sensitivity plus specificity while the “balanced” cut‐off was defined as that PC 20 at which sensitivity and specificity were most equal. Results: 70/348 children (20.1%) were diagnosed with asthma. The optimal and balanced PC 20 cut‐offs, both for all children and for females alone, were respectively 3 mg/ml (sensitivity 80.0%, specificity 49.1%) and 2 mg/ml (sensitivity 63.1%, specificity 64.7%). For males alone, the “optimal” and “balanced” PC 20 cut‐offs were both 2 mg/ml. Conclusion: For this cohort of 7‐year olds at high risk for asthma, methacholine challenge testing using a cut‐off value of PC 20 3 mg/ml conferred the maximal sum of specificity plus sensitivity. For contexts in which higher sensitivity or specificity is desired, other cut‐offs may be preferred. Pediatr. Pulmonol. 2011; 46:175–178. © 2011 Wiley‐Liss, Inc.