Interaction between Asthma and Lung Function Growth in Early Life.
Am J Respir Crit Care Med. 2012 Mar 29. Bisgaard H, Jensen SM, Bønnelykke K. Copenhagen Prospective Studies on Asthma in Childhood;, Health Sciences, University of Copenhagen; Copenhagen University Hospital, Gentofte, Copenhagen, Denmark.
Rationale: The causal direction between asthma and lung function deficit is unknown, but important for the focus of preventive measures and research into the origins of asthma.
Objectives: To analyze interaction between lung function development and asthma from birth to 7 years of age.
Methods: The Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) is a prospective clinical study of a birth-cohort of 411 at-risk children. Spirometry was completed in 403 (98%) neonates and again by age 7 in 317 children (77%).
Measurements: Neonatal spirometry and bronchial responsiveness to methacholine was measured during sedation by forced flow-volume measurements. Asthma was diagnosed prospectively from daily diary cards and 6-monthly clinic visits.
Main Results: Children with asthma by age 7 (14%) already had a significant airflow deficit as neonates (FEF50 reduced by 0•34 Z-score by 1 month, p=0•03). This deficit progressed significantly during early childhood (FEF50 reduced by 0•82 Z-scores by age 7, p<0•0001), suggesting that approximately 40% of the airflow deficit associated with asthma is present at birth while 60% develops with clinical disease. Environmental tobacco exposure, but not allergic sensitization, also hampered airflow growth. Bronchial responsiveness to methacholine in the neonates was associated with the development of asthma, p=0.01.
Conclusions: Children developing asthma by age 7 had a lung function deficit and increased bronchial responsiveness as neonates. This lung function deficit progressed to age 7. Therefore research into the origins and prevention of asthma should consider early life both before and after birth.