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Exhaled breath condensate pH & atopic sensitization predict school age asthma

Published online: April 1, 2021

The diagnosis of asthma in early childhood is challenging due to an overlap of symptoms between asthma and wheezy bronchitis (reactive airway disease). For this reason, more precise approaches to diagnosing asthma in young children are needed. In recent years, deaerated exhaled breath condensate (dEBC) pH has been shown to be an especially promising and non-invasive method which can be applied at any age. However, there have not been any prospective studies that would allow evaluating the ability of dEBC pH to predict the risk of wheezing pre-schoolers to develop asthma in the future.

A study by Krei├čl and Hendler et al., recently published in The Journal of Allergy and Clinical Immunology: In Practice, provides a follow-up assessment of a cohort of preschool children with the objective to evaluate the ability of preschool dEBC pH to predict asthma risk at school age. The initial exam had been performed when the children were preschool age. In this re-assessment 4 years later, the children had reached school age and asthma diagnosis was evaluated according to the Global Initiative for Asthma recommendations in 135 children who at baseline had been classified into the following groups: (asymptomatic) atopic wheezers (30 children), (asymptomatic) non-atopic wheezers (57 children), children with allergic rhinitis only (14 participants), and healthy controls (34 children).

All former atopic wheezers, 12 (21%) non-atopic wheezers, 2 (14%) children with allergic rhinitis, and 1 (3%) healthy control developed asthma at follow-up. Among all children with baseline wheezing, baseline dEBC pH predicted asthma at follow-up with a probability of 72% (sensitivity, 0.67; specificity, 0.76; at pH 7.83). Combining dEBC pH and atopic sensitization (CAP class) only marginally increased probability but led to substantial gain in sensitivity (0.96) and negative predictive value (NPV, 0.94). Additional clinical information (Asthma Predictive Index, Family Atopy, Family Asthma, need for inhaled corticosteroid treatment) further increased the potential to predict asthma (to 94%) and raised sensitivity (0.98) and NPV (0.97) to nearly perfect values.
The results of this prospective study suggest that dEBC pH combined with information about atopic sensitization and additional clinical parameters may serve as a highly sensitive prognostic, non-invasive composite marker for the early detection of young asymptomatic preschool children with increased risk of developing asthma. Including the criteria of allergic sensitization might additionally help to exclude other chronic diseases with lung function alterations or bronchial hyperresponsiveness.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.