Does bronchial hyperresponsiveness in childhood predict active asthma in adolescence?

Rationale: Bronchial hyperresponsiveness (BHR) is an important, but not specific, asthma characteristic. Objectives: We aimed to assess the predictive value of BHR tested by methacholine and exercise challenge at age 10 years for active asthma 6 years later. Methods: From a Norwegian birth cohort, 530 children underwent methacholine challenge and exercise-induced bronchoconstriction (EIB) test (n = 478) at 10 years and structured interview and clinical examination at age 16 years. The methacholine dose causing 20% reduction in FEV(1) (PD(20)) and the reduction in FEV(1) (%) after a standardized treadmill test were used for BHR assessment. Active asthma was defined with at least two criteria positive: doctor's diagnosis of asthma, symptoms of asthma, and/or treatment for asthma in the last year. Measurements and Main Results: PD(20) and EIB at 10 years of age increased the risk of asthma (β = 0.94 [95% confidence interval (CI), 0.92-0.96] per μmol methacholine and β = 1.10 [95% CI, 1.06-1.15] per %, respectively). Separately the tests explained 10 and 7%, respectively, and together 14% of the variation in active asthma 6 years later. The predicted probability for active asthma at the age of 16 years increased with decreasing PD(20) and increasing EIB. The area under the curve (receiver operating characteristic curves) was larger for PD(20) (0.69; 95% CI, 0.62-0.75) than for EIB (0.60; 95% CI, 0.53-0.67). Conclusions: BHR at 10 years was a significant but modest predictor of active asthma 6 years later, with methacholine challenge being superior to exercise test.     

Effects of early intake of fruit or vegetables in relation to later asthma and allergic sensitization in school-age children

AIM: To assess the associations between nutrition supplements in infancy and later asthma and allergy in school-age children, and to explore the impact of environmental factors in early life. METHODS: Five hundred and two children underwent clinical examination, skin prick test and a second parentally completed questionnaire within 2 y of a cross-sectional questionnairebased study, including 4585 primary school children (6-16 y old) in 1994 from urban Oslo (37%), the mountainous area of Hallingdal (42%), and the industrial, coastal area of Odda (21%). The children were selected from the 1994 survey on the basis of reported diagnosed asthma (n=166), wheeze in the last 12 mo (n=155) and no asthma/no wheeze (n=181). Questions were related to nutrition and environmental exposure in early life. Possible associations between allergic sensitization or asthma at school age and exposures were estimated by logistic regression analysis, adjusting for potential confounders. RESULTS: Daily intake of fresh fruit or vegetables, but not extra vitamins or cod liver oil supplements, in infancy decreased the risk of asthma (adjusted odds ratio (aOR) 0.57 (95% confidence interval (CI): 0.37-0.88). Early supplements of cod liver oil and extra vitamins were associated with increased allergic sensitization (aOR 1.78 (95% CI: 1.03-3.07) and 1.71 (95% CI: 1.01-2.88), respectively). A significantly higher prevalence of allergic sensitization was found in children living in Hallingdal compared to Odda, while the latter children, on the other hand, had the highest prevalence of house dust mite allergy (p = 0.001 vs Hallingdal and p = 0.04 vs Oslo). CONCLUSION: The present study suggests that the early introduction of daily fresh fruit or vegetables may decrease the risk of asthma after 1 y of life, whereas allergic sensitization at school age seemed to increase with extra vitamin and cod liver oil supplements during infancy. Living area influenced allergic sensitization, with differences between coastal and inland areas.     

Childhood Asthma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations

Objectives

Recent studies have explored the potential for swimming pool disinfection by-products (DBPs), which are respiratory irritants, to cause asthma in young children. Here we describe the state of the science on methods for understanding children’s exposure to DBPs and biologics at swimming pools and associations with new-onset childhood asthma and recommend a research agenda to improve our understanding of this issue.

Data sources

A workshop was held in Leuven, Belgium, 21–23 August 2007, to evaluate the literature and to develop a research agenda to better understand children’s exposures in the swimming pool environment and their potential associations with new-onset asthma. Participants, including clinicians, epidemiologists, exposure scientists, pool operations experts, and chemists, reviewed the literature, prepared background summaries, and held extensive discussions on the relevant published studies, knowledge of asthma characterization and exposures at swimming pools, and epidemiologic study designs.

Synthesis

Childhood swimming and new-onset childhood asthma have clear implications for public health. If attendance at indoor pools increases risk of childhood asthma, then concerns are warranted and action is necessary. If there is no such relationship, these concerns could unnecessarily deter children from indoor swimming and/or compromise water disinfection.

Conclusions

Current evidence of an association between childhood swimming and new-onset asthma is suggestive but not conclusive. Important data gaps need to be filled, particularly in exposure assessment and characterization of asthma in the very young. Participants recommended that additional evaluations using a multidisciplinary approach are needed to determine whether a clear association exists.     

Sports in extreme conditions: The impact of exercise in cold temperatures on asthma and bronchial hyper-responsiveness in athletes

Exercise-induced asthma (EIA) and bronchial hyper-responsiveness (BHR) are frequently reported among elite athletes of outdoor endurance winter sports, particularly in cross-country and biathlon skiers. The pathogenesis of EIA is related to water loss and heat-loss through the increased respiration during exercise, leading to mediator release, airways inflammation and increased parasympathetic nervous activity in the airways, causing bronchial constriction and BHR. In the competing elite athlete this is presently considered to be due to the frequently repeated increased ventilation during training and competitions in combination with the repeated environmental exposure to cold air in outdoor winter sports. It is important that athletes at risk of asthma and BHR are monitored through regular medical control with assessment of lung function and BHR, and when BHR or asthma is diagnosed, optimal controlling treatment through anti-inflammatory treatment by inhaled steroids should be started and relieving treatment (inhaled ipratropium bromide and inhaled β2-agonists) should be used to relieve bronchial constriction if present.     

CFTR gene mutations and asthma in the Norwegian Environment and Childhood Asthma study

BACKGROUND: Several candidate genes have been implicated in the etiology of asthma, including the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR). Mutations in the CFTR gene result in derangements of mucociliary clearance. Homozygotes for CFTR mutations develop cystic fibrosis (CF), a disorder characterized mainly by lung and pancreas disease. OBJECTIVE: To investigate whether there was an increased frequency of CFTR mutations in asthma patients. METHODS: Seven hundred and three subjects aged 10-11 years from the environment and childhood asthma (ECA) study were included in the present study. Possible associations between asthma, reduced lung function, bronchial hyperresponsiveness (BHR), and increased or decreased nitrogen oxide (NO) levels (based on structural parental interview, spirometry, PD20 methacholine challenge test and exhaled NO measurements), and the five most common CFTR mutations in Norway (DeltaF508, R117H, R117C, 4005+2T-->C, 394delTT), the modulating polymorphisms IVS8(TG)mTn and the IVS8-5T were investigated. RESULTS: No association were found between asthma, reduced lung function, BHR or exhaled NO levels and CF heterozygosity. However, the IVS8(TG)11T7 haplotype was associated with normal lung function. CONCLUSIONS: Our results do not support the hypothesis that CFTR mutations or polymorphisms play a role in the pathogenesis of asthma in children. However, the distribution of Tn(TG)m haplotypes differed between individuals with reduced lung function and individuals with normal lung function.     

Asthma in adolescent athletes

Athletes active in endurance sports are at an increased risk of acquiring asthma through their sports activities, especially so for cross-country skiers, biathlon skiers, swimmers and athletes of other endurance sports. Asthma may be present from early childhood or develop while in active sports. This article focuses on the physical activity and sports activities in children and adolescents. Exercise-induced asthma (EIA) is found in 8-10% of a normal child population of school age and in about 35% of children with current asthma. EIA is caused by the markedly increased ventilation during exercise, with increased heat and water loss through respiration, leading to bronchial constriction. The risk of developing asthma in the young athlete is related to the repeated daily training activity with increased epithelial damage of the airways, delayed repair due to the daily repetition of the training and increased airway mucosal inflammation. The increased environmental exposure through the sports activity to environmental agents, such as cold, dry air in skiers and chlorine compounds in swimmers, increases symptoms and signs of asthma and bronchial hyper-responsiveness, either worsening an existing asthma or leading to a novel disease in a previously healthy athlete. Several specific aspects of daily training life, environmental exposure, diagnostic procedures and aspects of treatment related to the regulations of medication use in sports need particular attention when addressing the adolescent athlete with respiratory symptoms.