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Relationship between bronchial responsiveness and clinical evolution in infants who wheeze: a four-year prospective
C Delacourt1, M R Benoist, S Waernessyckle
1Laboratoire d'Explorations Fonctionnelles Respiratoires, Service de Pneumologie et Allergologie Pédiatriques, Hôpital des Enfants Malades, Paris, France.
Insights
Bronchial hyperresponsiveness in infants with recurrent wheezing does not predict persistent asthma. While hyperresponsiveness persists, it doesn't reliably identify children who will develop long-term asthma.
Area of Science:
- Pediatric Pulmonology
- Allergy and Immunology
- Respiratory Medicine
Background:
- Recurrent wheezing in early childhood is often transient.
- The role of bronchial hyperresponsiveness in persistent childhood asthma is not well understood.
- Predicting which infants with wheezing will develop persistent asthma is clinically important.
Purpose of the Study:
- To investigate if initial or persistent bronchial hyperresponsiveness differentiates infants with transient wheezing from those who develop persistent asthma.
- To assess the predictive value of bronchial hyperresponsiveness for asthma persistence in early childhood.
Main Methods:
- Prospective study of 129 infants with recurrent wheezing (≥3 episodes before 2 years).
- Clinical evaluations and methacholine challenges (measuring PD(15) PtcO(2)) every 6 months for 4 years, then annually.
- Assessment of VmaxFRC and SRaw values.
Main Results:
- Most children's wheezing resolved; 20% had persistent wheezing at 4 years.
- Persistent wheezers showed lower initial VmaxFRC and higher SRaw at follow-up.
- Bronchial hyperresponsiveness persisted in all children, but persistent wheezers had lower PD(15) PtcO(2) from 30 months; however, no reliable predictive cutoff was found.
Conclusions:
- The initial degree of bronchial hyperresponsiveness in infants with wheezing does not predict later asthma persistence.
- While bronchial hyperresponsiveness persists, its level at 30 months is not a reliable early predictor for subsequent clinical progression.
- Current measures of bronchial hyperresponsiveness in infancy are insufficient to predict the persistence of asthma into later childhood.
Abstract:
Recurrent illness involving wheezing during the first years of life is transient in most children. The role of bronchial hyperresponsiveness as a factor influencing the persistence of wheezing from infancy to school age remains unknown. In a prospective study we investigated whether infants who wheezed and subsequently developed persistent asthma differed from infants who wheezed and later became asymptomatic either in the initial degree of bronchial hyperresponsiveness or in the persistence of bronchial hyperresponsiveness with age. One hundred and twenty-nine infants with three or more wheezing episodes before 2 yr of age were followed during 4 yr with a clinical evaluation and a methacholine challenge performed every 6 mo until the child was 4 yr old and once per year thereafter. The clinical score significantly improved with time in most children. The proportion of children with persistent wheezing after 2 and 4 yr of follow-up was only 31% and 20%, respectively. Persistent wheezers had significantly lower VmaxFRC values at initial evaluation and higher SRaw values at the end of follow-up than infants who became asymptomatic. We used transcutaneous oxygen tension (PtcO(2)) to measure the response to methacholine. No significant difference in PD(15) PtcO(2) between groups with subsequently different clinical progression was observed at initial evaluation. Bronchial hyperresponsiveness persisted 4 yr later in all children but children with persistent wheezing showed significantly lower PD(15) PtcO(2) values than children who became asymptomatic, as early as 30 mo of age. However, an acceptable early PD(15) PtcO(2) cut-off point predictive for subsequent clinical progression could not be identified. The level of bronchial hyperresponsiveness in infants who wheezed was not predictive of the persistence of asthma 4 yr later.