Childhood factors that predict asthma in young adulthood

Prediction of adult asthma risk in early childhood using novel adult asthma predictive risk scores

BACKGROUND

Numerous risk scores have been developed to predict childhood asthma. However, they may not predict asthma beyond childhood. We aim to create childhood risk scores that predict development and persistence of asthma up to young adult life.

METHODS

The Isle of Wight Birth Cohort (n = 1456) was prospectively assessed up to 26 years of age. Asthma predictive scores were developed based on factors during the first 4 years, using logistic regression and tested for sensitivity, specificity and area under the curve (AUC) for prediction of asthma at (i) 18 and (ii) 26 years, and persistent asthma (PA) (iii) at 10 and 18 years, and (iv) at 10, 18 and 26 years. Models were internally and externally validated.

RESULTS

Four models were generated for prediction of each asthma outcome. ASthma PredIctive Risk scorE (ASPIRE)-1: a 2-factor model (recurrent wheeze [RW] and positive skin prick test [+SPT] at 4 years) for asthma at 18 years (sensitivity: 0.49, specificity: 0.80, AUC: 0.65). ASPIRE-2: a 3-factor model (RW, +SPT and maternal rhinitis) for asthma at 26 years (sensitivity: 0.60, specificity: 0.79, AUC: 0.73). ASPIRE-3: a 3-factor model (RW, +SPT and eczema at 4 years) for PA-18 (sensitivity: 0.63, specificity: 0.87, AUC: 0.77). ASPIRE-4: a 3-factor model (RW, +SPT at 4 years and recurrent chest infection at 2 years) for PA-26 (sensitivity: 0.68, specificity: 0.87, AUC: 0.80). ASPIRE-1 and ASPIRE-3 scores were replicated externally. Further assessments indicated that ASPIRE-1 can be used in place of ASPIRE-2-4 with same predictive accuracy.

CONCLUSION

ASPIRE predicts persistent asthma up to young adult life.

Prospective study of disease persistence and lung function trajectories of childhood asthma

BACKGROUND

A proportion of asthmatic children outgrow their disease by adulthood, but there are limited data on predictors for asthma persistence. This prospective study characterized the trajectory of spirometric indices and identified predictors for the persistence of childhood asthma.

METHODS

Chinese asthmatic children aged 6-15 years from pediatric allergy clinic underwent annual visits for ≥5 years and until their adulthood. Pre-bronchodilator spirometry and anti-asthma medications were recorded at baseline and then at least annually. Asthma resolution was defined when patients were free from asthma symptoms and use of anti-asthma drugs for ≥2 years. Logistic regression was used to identify predictors for asthma persistence. Generalized estimating equation was used to analyze longitudinal changes in lung function parameters in relation to asthma persistence.

RESULTS

181 asthmatic children aged [mean (SD)] 10.0 (2.7) years were followed for [mean (SD)] 12.5 (2.8) years. One third of them outgrew asthma during follow-up. Female was 3.36 times more likely to have persistent asthma. Inhaled corticosteroid (ICS) treatment ever and frequent asthma exacerbation (AE) predicted asthma persistence with respective odds ratios of 3.19 (95% confidence interval [CI] 1.44-7.09) and 3.05 (95% CI 1.39-6.68). Persistent asthma was inversely associated with baseline forced expiratory volume in 1-second (FEV₁ %) with an odds ratio of 0.96 (95% CI 0.93-1.00). Throughout follow-up, patients with persistent asthma had generally lower forced expiratory indices than those with asthma resolution. Children with persistent asthma experienced poorer lung function growth.

CONCLUSIONS

Female, ICS ever, and frequent AE predicted persistent asthma. Patients with persistent asthma had lower forced expiratory indices and poorer lung function growth into adulthood.

Sex-based differences in factors associated with bronchial hyperresponsiveness in adolescents with childhood asthma

BACKGROUND

Bronchial hyperresponsiveness (BHR), an important physiological feature of asthma, is a prognostic marker of childhood asthma.

PURPOSE

We aimed to investigate the factors associated with BHR in adolescents with childhood asthma.

METHODS

Two hundred and fifteen adolescents (≥13 years of age; 149 males, 66 females) who were diagnosed with asthma during childhood were enrolled, underwent methacholine challenge tests, and were divided into the BHR group (<25 mg/mL of provocation concentration causing a 20% fall in forced expiratory volume in 1 second [FEV1] [PC20], n=113) or non-BHR group (≥25 mg/mL of PC20, n=102). We examined longitudinal changes in BHR and the risk factors for its persistence in the 108 adolescents for whom baseline data, including methacholine PC20 at age 6 years, were available. Multivariate logistic regression analyses were performed to assess the factors associated with BHR in adolescents.

RESULTS

Mold sensitization (adjusted odds ratio [aOR], 5.569; P=0.005) and increased blood eosinophil count (aOR, 1.002; P=0.026) were independently associated with BHR in boys but not girls. The odds of BHR decreased by 32% with each 1-year increase in age in boys (aOR, 0.683; P=0.010) but not girls. A reduced FEV1/forced vital capacity ratio (<90%) was independently related with BHR in female patients only (aOR, 7.500; P=0.007). BHR decreased with age throughout childhood. A low methacholine PC20 at age 6 years was independently associated with persistent BHR throughout childhood in male and female patients, whereas early mold sensitization was a risk factor for persistent BHR in male patients only (aOR, 7.718; P=0.028).

CONCLUSION

Our study revealed sex-specific differences in the factors associated with BHR in adolescents with childhood asthma. Our findings suggest the risk factors that might affect asthma transition from childhood to adolescence and adulthood.

Moving toward consensus on diagnosis and management of severe asthma in children

Children with severe asthma continue to experience symptoms despite long-term treatment with high doses of corticosteroids. Moreover, the heterogeneous nature of asthma and the presence of several phenotypes have limited our ability to develop an optimized management strategy for these patients. Adequate management of severe asthma in children necessitates a detailed understanding of what makes asthma difficult to control, knowledge of the causal factors, review of diagnosis for accurate identification of pediatric patients with severe asthma and a precise definition of the phenotypes to be able to better target the therapy. Advancement in all these aspects is likely to improve childhood asthma treatment in the future. Although our understanding of severe pediatric asthma has grown in recent years, there remains a lack of consensus and clarity around critical aspects of this condition. This review attempts to present a harmonized view on the definition of severe asthma in the pediatric age group, identification of phenotypes and diagnosis, the inflammatory cascade, pharmacological and non-pharmacological treatment strategies, considerations for follow-up and referral to specialists, and disease prevention strategies.

Diagnosing asthma and chronic obstructive pulmonary disease with machine learning

This study examines the clinical decision support systems in healthcare, in particular about the prevention, diagnosis and treatment of respiratory diseases, such as Asthma and chronic obstructive pulmonary disease. The empirical pulmonology study of a representative sample (n = 132) attempts to identify the major factors that contribute to the diagnosis of these diseases. Machine learning results show that in chronic obstructive pulmonary disease's case, Random Forest classifier outperforms other techniques with 97.7 per cent precision, while the most prominent attributes for diagnosis are smoking, forced expiratory volume 1, age and forced vital capacity. In asthma's case, the best precision, 80.3 per cent, is achieved again with the Random Forest classifier, while the most prominent attribute is MEF2575.

Increased Bronchial Hyperresponsiveness and Higher Asymmetric Dimethylarginine Levels after Fetal Growth Restriction

Bronchial hyperresponsiveness (BHR), a feature of asthma, is observed in preterm-born children and has been linked to intrauterine growth restriction. BHR is mediated via airway smooth muscle tone and is modulated by the autonomic nervous system, nitric oxide, and airway inflammation. Interactions among these factors are insufficiently understood. Methacholine-induced BHR (Met-BHR), fractional exhaled NO, and systemic soluble markers of nitric oxide metabolism and inflammation were determined in a population-based sample of 57 eleven-year-old children born extremely preterm (gestational age [GA] < 28 wk) or with extremely low birth weight (<1,000 g), and in a matched normal-birth weight term-born control group (n = 54). Bronchopulmonary dysplasia (BPD) was defined as the need for oxygen treatment at a GA of 36 weeks. In preterm-born children, birth weight below the 10th percentile for GA was associated with increased Met-BHR and higher plasma levels of asymmetric dimethylarginine (ADMA), with an increased odds ratio for being in the upper tertile of Met-BHR (11.8; 95% confidence interval, 3.3-42.4) and of ADMA (5.2; 95% confidence interval, 1.3-20.3). Met-BHR was correlated to ADMA level (r = 0.27, P = 0.007). There were no significant differences in Met-BHR, fractional exhaled NO, or z-FEV₁ according to BPD status. No associations with systemic soluble markers of inflammation were observed for Met-BHR, birth, or BPD status. Intrauterine growth restriction in preterm-born children was associated with substantially increased Met-BHR and higher ADMA levels, suggesting altered nitric oxide regulation. These findings contribute to the understanding of the consequences from an adverse fetal environment; they should also be tested in term-born children.

Asthma and sleep disturbance in adolescents and young adults: A cohort study

AIMS

A longitudinal birth cohort provides an opportunity to study the impact of childhood conditions persisting into adulthood. This study examines the cross-sectional association of asthma with sleep quality and snoring in the adolescent and young adult population and the extent to which asthma, sleep quality and snoring at 14 years independently predict themselves or each other at 21 years.

METHODS

Data from a 21-year follow-up of mothers and their children recruited into the Mater-University of Queensland Study of Pregnancy (n = 7223). Complete asthma and sleep information (questionnaire data) was available for 5015 participants at 14 years and 3527 at 21 years, with 3237 participants at both 14 and 21 years.

RESULTS

Poor sleep quality and snoring were independently associated with asthma at 14 years and 21 years, with stronger associations evident in women. At 21 years, associations were mediated by asthma symptom severity. Asthma, sleep quality and snoring at 14 years each strongly and independently predicted themselves at 21 years. Asthma at 14 years predicted snoring at 21 years, while poor sleep quality and snoring in women predicted asthma at 21 years, the latter partially mediated by body mass index.

CONCLUSIONS

The relationship between asthma, sleep quality and snoring varied by gender. Sleep quality and snoring should be considered in the assessment and holistic management of asthma. The predictive relationship seen between 14 and 21 years provides an opportunity to address these issues at a younger age.

Update on the current methods for the diagnosis and treatment of severe childhood asthma

The level of asthma control is the key outcome towards which asthma management is evaluated. The majority of children with asthma can obtain adequate control of symptoms through avoidance of triggering factors and/or with the help of low to moderate doses of current available medications. However, there is still a group of children with poor symptom control despite intensive treatment. The current review will provide an overview of a standardized approach to characterize this heterogeneous group of severely sick children. Factors that attenuate the effect of the prescribed treatment and make asthma difficult to treat are discussed. In addition, the usefulness of current methods of assessing asthma severity, pulmonary function, allergy and airway inflammation is also described. Finally, an overview of therapeutic options for children with severe asthma is provided.

Impulse oscillometry in acute and stable asthmatic children: a comparison with spirometry

OBJECTIVE

Lung function tests have attracted interest for the diagnosis and follow-up of childhood asthma in recent years. For patients who cannot perform forced expiratory maneuvers, impulse oscillometry (IOS), performed during spontaneous breathing, may be an alternative tool.

METHODS

Thirty-five acute, 107 stable asthmatic and 103 healthy children who presented to our clinic performed IOS followed by spirometry before and after salbutamol inhalation. The mean baseline and reversibility of IOS and spirometry parameters were compared between the groups. Correlation analyses were undertaken within the asthmatics, and the healthy controls separately. To distinguish the three groups, the sensitivity and specificity of baseline and reversibility values of IOS and spirometry were computed. When spirometry was taken as the gold standard, the discriminating performance of IOS to detect the airway obstruction and reversibility was investigated.

RESULTS

The mean absolute values of Zrs, R5, R5-R20, X5, X10, X15, Fres, AX, and all spirometric parameters, and the mean reversibility values of R5, R10, Fres, AX and forced expiratory volume in one second were different between the groups and the highest area under curve values to discriminate the groups was obtained from area of reactance (AX) and ΔAX. Zrs, all resistance (including R5-R20) and reactance parameters, Fres and AX were correlated with at least one spirometric parameter. Spirometric reversibility was detected by ≤-22.34 and ≤-39.05 cut-off values of ΔR5 and ΔAX, respectively.

CONCLUSIONS

IOS has shown a highly significant association with spirometric indices and reversibility testing. It may be a substitute for spirometry in children who fail to perform forced expiratory maneuvers.

Allergic sensitization is age-dependently associated with rhinitis, but less so with asthma

BACKGROUND

Epidemiologic data describing the association between allergic sensitization and asthma and allergic rhinitis in adults are scarce.

OBJECTIVE

To determine the prevalence and impact of specific sensitization to airborne allergens on asthma and allergic rhinitis among adults in relation to age.

METHODS

A random population sample (age 21-86 years) was examined with structured interview and analysis of specific IgE to 9 common airborne allergens. Of those invited, 692 (68%) subjects participated in blood sampling. IgE level of 0.35 U/mL or more to the specific allergen was defined as a positive test result.

RESULTS

Allergic sensitization decreased with increasing age, both in the population sample and among subjects with asthma and allergic rhinitis. In a multivariate model, sensitization to animal was significantly positively associated with asthma (odds ratio [OR], 4.80; 95% CI, 2.68-8.60), whereas sensitization to both animal (OR, 3.90; 95% CI, 2.31-6.58) and pollen (OR, 4.25; 95% CI, 2.55-7.06) was significantly associated with allergic rhinitis. The association between allergic sensitization and rhinitis was consistently strongest among the youngest age group, whereas this pattern was not found for asthma. The prevalence of allergic sensitization among patients with asthma decreased by increasing age of asthma onset, 86% with asthma onset at age 6 y or less, 56% at age 7 to 19 years, and 26% with asthma onset at age 20 years or more.

CONCLUSIONS

Sensitization to animal was associated with asthma across all age groups; allergic rhinitis was associated with sensitization to both pollen and animal and consistently stronger among younger than among older adults. Early onset of asthma was associated with allergic sensitization among adults with asthma.

Development of rhinitis may be an indicator for the persistence of childhood asthma

OBJECTIVES

Results of previous studies have established several factors related with the natural course of childhood asthma. The aim of this study is to investigate the prognosis of childhood asthma and to determine possible risk factors for disease persistence.

METHODS

An outpatient cohort with a median (interquartile range) follow-up duration of 19.4 (17.7-21.8) years was re-evaluated. Current clinical remission (CR) was defined as no asthma symptoms and no use of controller medication within the past year.

RESULTS

Out of 115 patients, 78 could be surveyed with questionnaire and 46 patients with a median age of 25.3 (23.9-27.0) years were further investigated with clinical work-up. Nineteen (24.4%) patients were in CR in both visits (adolescence and young adulthood). A further 7 patients (9.0%) who were not in CR at adolescence were in CR at the young adulthood visit. However, 21 patients (26.9%) who were in CR at adolescence were not in CR at the young adulthood visit. Thirty-one patients (39.7%) with persistent symptoms at adolescence were not in CR at young adulthood, either. In multivariate logistic models, the presence of obstructive pattern (forced expiratory volume in 1s (FEV1)/forced vital capacity (FVC) <80% vs. ≥80%) in pulmonary function tests during the adolescence period (odds ratio; [95% confidence interval] (6.71 [1.65-27.29]; p=0.008) and later-onset rhinitis (10.27 [1.18-89.13]; p=0.035) predicted the absence of CR at young adulthood.

CONCLUSION

A substantial number of patients who were in CR during adolescence have re-emerging disease. The presence of obstructive pattern in adolescence and later-onset rhinitis were associated with the absence of CR in young adults with asthma. Awareness of risk factors along with early interventions may provide better results in childhood asthma.

Trends in adult current asthma prevalence and contributing risk factors in the United States by state: 2000-2009

BACKGROUND

Current asthma prevalence among adults in the United States has reached historically high levels. Although national-level estimates indicate that asthma prevalence among adults increased by 33% from 2000 to 2009, state-specific temporal trends of current asthma prevalence and their contributing risk factors have not been explored.

METHODS

We used 2000-2009 Behavioral Risk Factor Surveillance System data from all 50 states and the District of Columbia (D.C.) to estimate state-specific current asthma prevalence by 2-year periods (2000-2001, 2002-2003, 2004-2005, 2006-2007, 2008-2009). We fitted a series of four logistic-regression models for each state to evaluate whether there was a statistically significant linear change in the current asthma prevalence over time, accounting for sociodemographic factors, smoking status, and weight status (using body mass index as the indicator).

RESULTS

During 2000-2009, current asthma prevalence increased in all 50 states and D.C., with significant increases in 46/50 (92%) states and D.C. After accounting for weight status in the model series with sociodemographic factors, and smoking status, 10 states (AR, AZ, IA, IL, KS, ME, MT, UT, WV, and WY) that had previously shown a significant increase did not show a significant increase in current asthma prevalence.

CONCLUSIONS

There was a significant increasing trend in state-specific current asthma prevalence among adults from 2000 to 2009 in most states in the United States. Obesity prevalence appears to contribute to increased current asthma prevalence in some states.

The long-term outcomes of persistent childhood allergic asthma: a cross-sectional study from western Anatolia: childhood persistent asthma in western Anatolia

BACKGROUND

Prospective cohort studies have provided useful knowledge about the natural history of asthma. However, most of the studies are conducted in western countries but the course of the disease and long-term outcomes may differ between countries due to environmental and cultural factors.

OBJECTIVE

The aim of this study is to describe the long-term outcomes of childhood asthma, with data from a follow-up study of at least 10 years, in western Anatolia, Turkey.

METHODS

Fifty-two patients diagnosed with persistent allergic asthma participated in the study. The patient's demographics, findings on admission, age at onset of disease, time of diagnosis, history of other allergic conditions, history of parental asthma and allergic disorders, presence of pharmacotherapy and immunotherapy were obtained from patients' records. The factors influencing remission at the end of 10 years follow-up were evaluated.

RESULTS

A total of 20 patients (38.5%) were on remission at the end of 10 years. The type of allergen, multi-allergen sensitivity, eosinophilia and elevated serum immunoglobulin E on admission, accompanying allergic disorders and atopy in parents, and allergen immunotherapy did not affect the remission rate (p>0.05).

CONCLUSION

Childhood persistent asthma is not a homogeneous clinical entity but high clinical remission rates are obtained in western Anatolia. There is no significant predictor of clinical remission in long term follow-up. Prospective studies should be performed in larger asthmatic populations to obtain further data about the natural course of childhood asthma.

Remission and persistence of asthma followed from 7 to 19 years of age

BACKGROUND AND OBJECTIVE

To date, a limited number of population-based studies have prospectively evaluated the remission of childhood asthma. This work was intended to study the remission and persistence of childhood asthma and related factors.

METHODS

In 1996, a questionnaire was distributed to the parents of all children aged 7 to 8 years in 3 municipalities in northern Sweden, and 3430 (97%) participated. After a validation study, 248 children were identified as having asthma; these children were reassessed annually until age 19 years when 205 (83%) remained. During the follow-up period lung function, bronchial challenge testing, and skin prick tests were performed. Remission was defined as no use of asthma medication and no wheeze during the past 12 months as reported at endpoint and in the 2 annual surveys preceding endpoint (ie, for ≥ 3 years).

RESULTS

At age 19 years, 21% were in remission, 38% had periodic asthma, and 41% persistent asthma. Remission was more common among boys. Sensitization to furred animals and a more severe asthma (asthma score ≥ 2) at age 7 to 8 years were both inversely associated with remission, odds ratio 0.14 (95% confidence interval 0.04-0.55) and 0.19 (0.07-0.54), respectively. Among children with these 2 characteristics, 82% had persistent asthma during adolescence. Asthma heredity, damp housing, rural living, and smoking were not associated with remission.

CONCLUSIONS

The probability of remission of childhood asthma from age 7- to 8-years to age 19 years was largely determined by sensitization status, particularly sensitization to animals, asthma severity, and female gender, factors all inversely related to remission.

Perinatal factors and respiratory health in children

BACKGROUND

There is conflicting evidence regarding the associations between anthropometric birth measures and asthma and lung function in children, particularly for apparently healthy infants born at term.

OBJECTIVE

Our objective was to elucidate these relationships paying particular attention to features of study design and analysis that may threaten the validity of previous studies in this field.

METHODS

We analysed data from a cohort of children with a family history of asthma who were recruited antenatally. Anthropometric birth measures and potential confounders were recorded at birth and within the first year of life. Lung function and asthma outcomes were measured at 8 years of age. Airway hyperresponsiveness (AHR) was measured by methacholine challenge. The potential for a reversal paradox, due to inclusion of covariates on the causal pathway, was investigated.

RESULTS

Four hundred and fifty (73% of the initial cohort) children were tested at age 8 years. Birth weight in the lowest tertile was associated with current asthma (OR 1.95, 95% CI 1.08, 3.54) and recent wheeze (OR 1.87, 95%CI 1.08, 3.24), but not with AHR (OR 1.37, 95% CI 0.68, 2.78). Birth weight was positively associated with lung function. Current height modified the relationship between birth length and lung function suggesting that post-natal growth has an effect on this relationship.

CONCLUSIONS

Low birth weight is associated with a greater risk of current asthma and lower lung function at 8 years in children with a family history of asthma. Current height should be treated as an effect modifier when investigating the fetal origins hypothesis.

Predicting Asthma Outcome Using Partial Least Square Regression and Artificial Neural Networks

The long-term solution to the asthma epidemic is believed to be prevention and not treatment of the established disease. Most cases of asthma begin during the first years of life; thus the early determination of which young children will have asthma later in their life counts as an important priority. Artificial neural networks (ANN) have been already utilized in medicine in order to improve the performance of the clinical decision-making tools. In this study, a new computational intelligence technique for the prediction of persistent asthma in children is presented. By employing partial least square regression, 9 out of 48 prognostic factors correlated to the persistent asthma have been chosen. Multilayer perceptron and probabilistic neural networks topologies have been investigated in order to obtain the best prediction accuracy. Based on the results, it is shown that the proposed system is able to predict the asthma outcome with a success of 96.77%. The ANN, with which these high rates of reliability were obtained, will help the doctors to identify which of the young patients are at a high risk of asthma disease progression. Moreover, this may lead to better treatment opportunities and hopefully better disease outcomes in adulthood.

Bronchial hyperresponsiveness in an adult population in Helsinki: decreased FEV1 , the main determinant

Introduction

Bronchial hyperresponsiveness (BHR) elevates the risk for development of respiratory symptoms and accelerates the decline in forced expiratory volume in the first second (FEV₁). We thus aimed to assess the prevalence, determinants and quantity of BHR in Helsinki.

Objectives

This study involved 292 randomly selected subjects age 26–66 years, women comprising 58%.

Methods

Following a structured interview, a spirometry, a bronchodilation test, and a skin-prick test, we assessed a bronchial challenge test with inhaled histamine using a dosimetric tidal breathing method. Results included the provocative dose inducing a decrease in FEV₁ by 15% (PD₁₅FEV₁) and the dose-response slope. For statistical risk factor-analyses, the severity of BHR was considered; PD₁₅ values ≤1.6 mg (BHR) and ≤0.4 mg [moderate or severe BHR (BHR_ms)] served as cut-off levels.

Results

BHR presented in 21.2% and BHR_ms in 6.2% of the subjects. FEV₁ < 80% of predicted [odds ratio (OR) 4.09], airway obstruction (FEV₁/forced vital capacity < 88% of predicted) (OR 4.33) and history of respiratory infection at age <5 (OR 2.65) yielded an increased risk for BHR as ORs in multivariate analysis. For BHR_ms, the determinants were decreased FEV₁ below 80% of predicted (OR 27.18) and airway obstruction (OR 6.16). Respiratory symptoms and asthma medication showed a significant association with BHR.

Conclusions

Of the adult population of Helsinki, 21% showed BHR to inhaled histamine. The main determinants were decreased FEV₁ and airway obstruction. Quantitative assessment of BHR by different cut-off levels provides a tool for characterization of phenotypes of airway disorders in epidemiologic and clinical studies.

Please cite this paper as: Juusela M, Pallasaho P, Sarna S, Piirilä P, Lundbäck B and Sovijärvi A. Bronchial hyperresponsiveness in an adult population in Helsinki: decreased FEV₁, the main determinant. Clin Respir J 2013; 7: 34–44.

An intelligent system approach for asthma prediction in symptomatic preschool children

Objectives. In this study a new method for asthma outcome prediction, which is based on Principal Component Analysis and Least Square Support Vector Machine Classifier, is presented. Most of the asthma cases appear during the first years of life. Thus, the early identification of young children being at high risk of developing persistent symptoms of the disease throughout childhood is an important public health priority. Methods. The proposed intelligent system consists of three stages. At the first stage, Principal Component Analysis is used for feature extraction and dimension reduction. At the second stage, the pattern classification is achieved by using Least Square Support Vector Machine Classifier. Finally, at the third stage the performance evaluation of the system is estimated by using classification accuracy and 10-fold cross-validation. Results. The proposed prediction system can be used in asthma outcome prediction with 95.54 % success as shown in the experimental results. Conclusions. This study indicates that the proposed system is a potentially useful decision support tool for predicting asthma outcome and that some risk factors enhance its predictive ability.

Lung dendritic cell developmental programming, environmental stimuli, and asthma in early periods of life

Dendritic cells (DCs) are important cells of our innate immune system. Their role is critical in inducing adaptive immunity, tolerance, or allergic response in peripheral organs—lung and skin. The lung DCs are not developed prenatally before birth. The DCs develop after birth presumably during the first year of life; exposures to any foreign antigen or infectious organisms during this period can significantly affect DC developmental programming and generation of distinct DC phenotypes and functions. These changes can have both short-term and long-term health effects which may be very relevant in childhood asthma and predisposition for a persistent response in adulthood. An understanding of DC development at molecular and cellular levels can help in protecting neonates and infants against problematic environmental exposures and developmental immunotoxicity. This knowledge can eventually help in designing novel pharmacological modulators to skew the DC characteristics and immune responses to benefit the host across a lifetime.

Positive exercise test and obstructive spirometry in young male conscripts associated with persistent asthma 20 years later

BACKGROUND

Asthma often begins in childhood or early adulthood and is a common disease among conscripts. The identification of long-term predictive factors for persistent asthma may lead to improved treatment opportunities and better disease control.

OBJECTIVE

Our aim was to study the prognostic factors of the severity of asthma among 40-year-old male conscripts whose asthma began in youth.

METHODS

We studied 119 conscripts who were referred to the Central Military Hospital during 1987-1990 due to asthma and who attended a follow-up visit approximately 20 years later. Asthma severity was evaluated during military service according to the medical records, and 20 years later during a follow-up visit using Global Initiative for Asthma guidelines. We used the results of lung function and allergy tests at baseline as predictors of current persistent asthma.

RESULTS

Compared with baseline, asthma was less severe at follow-up: 11.8% of subjects were in remission, 42.0% had intermittent asthma, 10.9% had mild persistent asthma, and 35.3% had moderate/severe persistent asthma (p < .001). In multivariate models, a positive exercise test at baseline yielded an odds ratio (OR) of 3.2 (95% CI 1.0-9.8, p = .046), a decreased FEV1/FVC % predicted an OR of 4.0 (95% CI 1.7-9.3, p = .002), and a decreased FEF50% % predicted an OR of 2.8 (95% CI 1.3-6.4, p = .012) for current persistent asthma.

CONCLUSIONS

About half of the men had persistent asthma at the 20-year follow-up. Positive exercise tests and obstructive spirometry results were related to the persistence of asthma and may be useful long-term prognostic factors for asthma severity.

Health impacts of air pollution: a life course approach for examining predictors of respiratory health in adulthood

PURPOSE

This research applies a life course health development framework to examine the impacts of childhood exposure to air pollution on respiratory health in adulthood.

METHODS

This prospective cohort study uses data collected from children originally studied in the 1970/1980s, including exposure to air pollution, indoor exposures, sociodemographic variables, and health outcomes data. Thirty years later, a self-administered questionnaire was used to collect data from adulthood on health status, occupational and residential histories, socioeconomic status, and lifestyle.

RESULTS

Overall, 29% of respondents were diagnosed with at least one respiratory condition and 24% have persistent respiratory symptoms in adulthood. Significant neighborhood differences in exposure variables and adulthood health outcomes were found. Predictors of adulthood respiratory health include asthma diagnosis or chest illness in childhood, parental record of respiratory symptoms, other medical diagnosis in adulthood, fair/poor self-perceived health, smoking/exposure to smoking, and residing in a property built before 1950. Results suggest that exposure to ambient total suspended particulates in childhood is preventative for diagnosis with at least one respiratory condition in adulthood.

CONCLUSION

Findings suggest that long-term childhood exposure to air pollution does not predict respiratory conditions and symptoms in adulthood. However, respiratory health in childhood predicts adulthood respiratory health, thus suggesting that the health impacts of any exposures that impact respiratory health during critical or sensitive times in childhood are long term.

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.

Predictors of respiratory symptoms in a rural Canadian population: A longitudinal study of respiratory health

BACKGROUND

Predictors of new and long-term respiratory symptoms for rural residents are not well defined.

OBJECTIVE

To identify early predictors of respiratory symptoms in a rural community population.

METHODS

The study population consisted of 871 adults living in the rural community of Humboldt, Saskatchewan, who participated in two cross-sectional respiratory studies conducted in 1993 and 2003. Questionnaire information obtained at both time points included respiratory symptoms (cough, phlegm and wheeze), history of allergy, smoking, and information regarding home and farm environments. Transitional modelling, in which measurement in a longitudinal sequence is described as a function of previous outcomes, was used to predict later outcomes of cough, phlegm and wheeze. Asymptomatic individuals in 1993 were assessed to determine factors associated with the development of symptoms during the study period.

RESULTS

The prevalences of cough, phlegm and wheeze in 1993 were 16.1%, 18.1% and 25.5%, respectively. Change in symptoms over time was significant for cough, phlegm and wheeze. The adjusted ORs (95% CI) from separate transitional models for each respiratory outcome in 1993 that predicted the same symptom in 2003 were 6.32 (4.02 to 9.95) for cough, 14.36 (9.01 to 22.89) for phlegm and 6.40 (4.40 to 9.32) for wheeze. For asymptomatic individuals in 1993, home dampness, allergic reaction to inhaled allergens and cigarette smoking were major risk factors associated with respiratory symptoms that were reported in 2003.

CONCLUSION

The presence of previous respiratory symptoms, allergies and environmental exposures can predict the occurrence of future respiratory symptoms in adults.

Diagnostic accuracy of clinical symptoms in obstructive airway diseases varied within different health care sectors

OBJECTIVE

To determine the diagnostic accuracy and diagnostic patterns of clinical symptoms in patients suspected to suffer from obstructive airway diseases (OADs) within different health care sectors.

STUDY DESIGN AND SETTING

Ten general practices (219 patients), one practice of pneumologists (259 patients) and one specialist hospital (300 patients). Sensitivities, specificities, positive (LR+), and negative (LR-) likelihood ratios of clinical symptoms were compared with lung function testing.

RESULTS

Thirty-one percent had chronic obstructive pulmonary disease (COPD), 21% had asthma. Sensitivities increased and specificities decreased from outpatient to hospital setting. The multivariate model of adjusted likelihood ratios for COPD showed LR+=4.86 (95% confidence interval [CI]=2.09-11.29) and LR-=0.07 (95% CI=0.01-0.43) of the combination "wheezing," "dyspnea when going upstairs," "smoking" in general practice. In hospital, the combination "dyspnea when going upstairs," "dyspnea during minimal exercise," and "smoking" showed LR+=3.34 (95% CI=2.08-5.31) and LR-=0.02 (95% CI=0.01-0.12). The combination "no coughing," "dyspnea attacks," and "no smoking" showed LR+=4.08 (95% CI=1.67-10.4) and LR-=0.24 (95% CI=0.12-0.58) for asthma in general practice. The combination "dyspnea attacks" and "no dyspnea when walking" showed LR+=6.48 (95% CI=1.01-40.94) and LR-=0.28 (95% CI=0.11-0.75) for asthma in hospital.

CONCLUSION

Clinical decision rules for OAD need to be derived from original studies in their respective settings or assessed on their transferability to other settings.

Bronchial hyperresponsiveness decreases through childhood

Limited knowledge exists about development of bronchial hyperresponsiveness (BHR) through adolescence. We aimed to assess changes in and risk factors for BHR in adolescence. From a Norwegian birth cohort 517 subjects underwent clinical examinations, structured interviews and methacholine challenges at age 10 and 16. BHR was divided into four categories: no BHR (cumulative methacholine dose required to reduce FEV(1) by 20% (PD(20)) >16 μmol), borderline BHR (PD(20) ≤16 and >8 μmol), mild to moderate BHR (PD(20) ≤8 and >1 μmol), and severe BHR (PD(20) ≤ 1 μmol). Logistic regression analysis was used to assess risk factors and possible confounders. The number of children with PD(20) ≤ 8 decreased from 172 (33%) to 79 (15%) from age 10-16 (p < 0.001). Most children (n = 295, 57%) remained in the same BHR (category) from age 10-16 (50% with no BHR), whereas the majority 182 (82%) of the 222 children who changed BHR category, had decreased severity at age 16. PD(20) ≤ 8 at age 10 was the major risk factor for PD(20) ≤ 8 6 years later (odds ratio 6.3), without significant confounding effect (>25% change) of gender, active rhinitis, active asthma, height, FEV(1)/FVC, or allergic sensitization. BHR decreased overall in severity through adolescence, was stable for the majority of children and only a minority (8%) had increased BHR from age 10 to 16. Mild to moderate and severe BHR at age 10 were major risk factors for PD(20) ≤ 8 at 16 years and not modified by asthma or body size.

Epidemiology of asthma: risk factors for development

This comprehensive review of the recent literature was undertaken to determine the current state of knowledge of the risk factors involved in the development of asthma in order to focus investigations in a proposed new longitudinal birth cohort study. The origins of asthma appear to lie in the prenatal and early postnatal period, and renewed investigations in this period with long-term close follow-up and objective phenotypic characterization will help to unravel the role of the multiple putative environmental factors in the development of asthma. It is only after understanding these effects that one can hope to design rational prevention studies for asthma.

Physical activity in young children is reduced with increasing bronchial responsiveness

BACKGROUND

Physical activity is essential for young children to develop adequately and for quality of life. It can be lower in children with subclinical asthma, and therefore methods to reveal subclinical reduction in physical activity in young children are warranted.

OBJECTIVE

We sought to study an association between physical activity in preschool children and objectively assessed intermediary asthma phenotypes.

METHODS

We studied 253 five-year-old children (127 girls) participating in the Copenhagen Prospective Studies on Asthma in Childhood. The main outcome measure was level of physical activity assessed objectively with accelerometers worn on an ankle for 4 weeks. Objective assessment of asthma intermediary phenotypes included prebronchodilator and postbronchodilator specific airway resistance, bronchial responsiveness to cold dry-air hyperventilation, and exhaled nitric oxide levels. Analyses were performed with generalized linear model and principal component analysis.

RESULTS

Physical activity was inversely associated with bronchial responsiveness (relative rate, 0.89; 95% CI, 0.83-0.95; P = .007) and significantly increased in the months of spring and summer (P < .001) and in boys (relative rate, 1.16; 95% CI, 1.09-1.25; P < .001). Physical activity was independent of asthma diagnosis, age, body mass index, baseline specific airway resistance, reversibility to beta(2)-agonist, sensitization, and exhaled nitric oxide level.

CONCLUSION

Physical activity in preschool children was reduced with increasing bronchial responsiveness. The reduced physical activity was subclinical and not realized by parents or doctors despite daily diary cards and close clinical follow-up since birth. This observation warrants awareness of even very mild asthma symptoms in clinical practice.

Early life factors associated with incidence of physician-diagnosed asthma in preschool children: results from the Canadian Early Childhood Development cohort study

Background. Asthma is a common childhood illness. The objective of this study is to determine the incidence of physician-diagnosed asthma in preschool years and its relationship to host, prenatal and postnatal factors, early childhood factors, parental factors, household factors and demographic factors. Methods. The study sample was comprised of 8,499 infants and toddlers (<2 years at baseline) enrolled in the Canadian Early Childhood Development Study. Incidence of asthma was determined when the children were in preschool age (2 to 5 years). Results. The 4-year cumulative incidence at preschool age was 13.7% for physician-diagnosed asthma. History of early childhood wheezing before 2 years of age was a significant risk factor for incidence of asthma in preschool years (hazard ratio (HR): 2.32; 95% confidence interval (CI): 2.04-2.65). Factors that were protective for the development of asthma were breastfeeding more than 3 months (HR: 0.82; 95% CI: 0.69-0.97); history of nose or throat infection often in childhood (HR: 0.79; 95% CI: 0.67-0.93); early daycare attendance (HR: 0.85; 95% CI: 0.74-0.98); presence of two or more siblings at birth, (HR: 0.79; 95% CI: 0.64-0.97); and dwelling in rural non- central metropolitan areas (HR: 0.81; 95% CI: 0.69-0.95). Male sex, low birth weight, childhood allergy, single parent, maternal smoking during pregnancy, maternal medication use, parental atopy, and low SES at baseline were significant risk factors for the incidence of physician-diagnosed asthma in preschool years. Conclusion. This study emphasizes the role of wheezing in infant and toddler age on early onset of asthma during preschool years. The results also provide additional importance of early exposures to environmental factors such as early infections, daycare attendance, and rural environment in the development of proper immune dynamics to prevent asthma.

Accuracy of ImmunoCAP Rapid in the diagnosis of allergic sensitization in children between 1 and 14 years with recurrent wheezing: the IReNE study

It is estimated that at least one out of three children with recurrent wheezing is atopic. Reliable diagnostic tools are needed in primary care that allow for adequate identification of these children. The purpose of this study was to assess the value of ImmunoCAP Rapid (ICR) Wheeze-Rhinitis Child in the identification of atopy with the use of 10 selected allergens in children with recurrent episodes of wheezing. A multicenter population study is based on primary care. It included children managed consecutively at the health center, who had three or more episodes of wheezing, at least one of them in the last 12 months. Each child completed a physical examination, an epidemiological survey, one capillary blood sampling (110 microl) for ICR, and one venous blood sampling for determination of Phadiatop Infant, total IgE and 10 specific IgE measurements. The children were identified as atopic, based on their clinical signs and symptoms and at least one positive specific IgE (0.35 kU(A)/l or higher), before knowing the results of ICR, Phadiatop Infant and total IgE. ICR was read by two independent observers. Six classes were evaluated, negative without any color and five positive degrees of pink-red color. Two hundred and fifteen children aged between 1 and 14 years were studied (138 boys); 50.7% were identified as atopic, 39.1% were sensitized only to inhalant allergens, 6.5% to food allergens and 5.1% to both. The predominant allergen was the dust mite (39.3%). For ICR, there were 2134 valid double observations. The Kappa index, comparing the negative results vs. any positive result, was 0.91 (95% CI: 0.88-0.94). The intraclass correlation coefficient was 0.98 (95% CI: 0.98-0.99). In the identification of a child as atopic, the positive post-test probability of ICR depended on the color degrees considered: 88.4% for any positive and 97.6% for the most intense tones. The positive post-test probability of Phadiatop Infant and total IgE was 95.6% and 68.2% respectively. ICR showed good reliability for the most prevalent allergen, the dust mite, with a sensitivity of 90.5% (95% CI: 82.1-95.8) and specificity of 88.5% (95% CI: 81.7-93.4). The analysis of the other allergens was limited by the small number of sensitized children. The analysis of receiver operating characteristic curves revealed an area under the curve of 0.84 (95% CI 0.80-0.88) for the cut-off point of specific IgE of 0.35 kU(A)/l and of 0.94(CI 0.91-0.97) for 2 kU(A)/l. A greater intensity of color of the lines of ICR was related to higher levels of specific IgE in blood. ICR is a reliable test for the identification of atopy in children, which identifies most children as atopic, and shows a good correlation in allergen-by-allergen identification. This suggests that it should be regarded as a first-rate tool, in the primary care clinic, for the evaluation of children with recurrent wheezing.

Can we be optimistic about asthma in childhood? A Greek cohort study

OBJECTIVE

To examine the prevalence and natural course of asthma from childhood to adolescence in a population-based, Greek birth cohort and to identify associated factors.

METHODS

Longitudinal information on asthma symptoms, physician diagnosed and treated, was available for 2133 children at 7 and 18 years of age.

RESULTS

The prevalence of current asthma was 9.0% and 5.0% at 7 and 18 years, respectively. The prevalence of lifetime asthma was 26.3% at 18 years. More than half of the children (58.2%) with early onset asthma were asymptomatic at 7 years and only 7.6% continued to have symptoms during adolescence. However, in 48.2% of those with late onset asthma, symptoms persisted up to 18 years. Logistic regression analyses showed that male gender, family history of atopy, active adolescent smoking and maternal smoking were significantly positively associated with lifetime asthma at 18 years. In addition, smoking during pregnancy was associated with an increased risk for persistence of asthma symptoms at 18 years. Asthma during childhood and active adolescent smoking were positively associated, and daily consumption of fruit and vegetables was negatively associated with current asthma at 18 years of age. Finally, children who were breastfed had a lower risk for lifetime asthma at 7 years.

CONCLUSION

The prevalence of asthma symptoms at 7 and 18 years of age was low throughout Greece. Our results suggest that, among others, nutrition is an important correlate of asthma in Greek children.

Childhood eczema and asthma incidence and persistence: a cohort study from childhood to middle age

BACKGROUND

The association between eczema and asthma is well documented, but the temporal sequence of this association has not been closely examined.

OBJECTIVES

To examine the association between childhood eczema and asthma incidence from preadolescence to middle age, and between childhood eczema and asthma persisting to middle age. A further aim was to examine any effect modification by nonallergic childhood exposures on the association between childhood eczema and both childhood asthma and later life incident asthma.

METHODS

Data were gathered from the 1968, 1974, and 2004 surveys of the Tasmanian Longitudinal Health Study. Multivariable logistic regression examined the association between childhood eczema and childhood asthma. Cox regression examined the association between childhood eczema and asthma incidence in preadolescence, adolescence, and adult life. Binomial regression examined the association between childhood eczema and childhood asthma persisting to age 44 years.

RESULTS

Childhood eczema was significantly associated with childhood asthma and with incident asthma in preadolescence (hazard ratio [HR], 1.70; 95% CI, 1.05-2.75), adolescence (HR, 2.14; 95% CI, 1.33-3.46), and adult life (HR, 1.63; 95% CI, 1.28-2.09). Although childhood eczema was significantly associated with asthma persisting from childhood to middle age (relative risk, 1.54; 95% CI, 1.17-2.04), this association was no longer evident when adjusted for allergic rhinitis.

CONCLUSION

Childhood eczema increased the likelihood of childhood asthma, of new-onset asthma in later life and of asthma persisting into middle age.

Airway responsiveness and inflammation in adolescent elite swimmers

BACKGROUND

Whereas increased airway hyperresponsiveness (AHR) and airway inflammation are well documented in adult elite athletes, it remains uncertain whether the same airway changes are present in adolescents involved in elite sport.

OBJECTIVE

To investigate airway responsiveness and airway inflammation in adolescent elite swimmers.

METHODS

We performed a cross-sectional study on adolescent elite swimmers (n = 33) and 2 control groups: unselected adolescents (n = 35) and adolescents with asthma (n = 32). The following tests were performed: questionnaire, exhaled nitric oxide (FeNO), spirometry, induced sputum, methacholine challenge, eucapnic voluntary hyperpnea (EVH) test, and exhaled breath condensate pH.

RESULTS

There were no differences in FeNO, exhaled breath condensate pH, cellular composition in sputum, or prevalence of AHR to either EVH or methacholine among the 3 groups. When looking at airway responsiveness as a continuous variable, the swimmers were more responsive to EVH than unselected subjects, but less responsive to methacholine compared with subjects with asthma. We found no differences in the prevalence of respiratory symptoms between the swimmers and the unselected adolescents. There was no difference in FeNO, cellular composition of sputum, airway reactivity, or prevalence of having AHR to methacholine and/or EVH between swimmers with and without respiratory symptoms.

CONCLUSION

Adolescent elite swimmers do not have significant signs of airway damage after only a few years of intense training and competition. This leads us to believe that elite swimmers do not have particularly susceptible airways when they take up competitive swimming when young, but that they develop respiratory symptoms, airway inflammation, and AHR during their swimming careers.

Clinical assessment of asthma progression in children and adults

Asthma is a heterogeneous disorder with a variable course, characterized by episodes of cough, wheezing and shortness of breath, reversible airflow limitation, and bronchial hyperresponsiveness. It begins early in life in many subjects with intermittent symptoms occurring with viral respiratory tract infections. Over time, and in genetically susceptible children (those with an atopic predisposition), the disease becomes more persistent with symptoms occurring in the absence of respiratory tract infections. Children with persistent wheezing are eventually diagnosed with asthma, with those at greatest risk having developed allergic sensitization early in life. Among children with asthma, some will have lifelong asthma with active symptoms and progressive loss of lung function over time, whereas other children will undergo asthma remission in adolescence. Once in remission, the disease may remain quiescent, or it may relapse in midadult life. This review focuses on studies that have enhanced our understanding of the progression of asthma from infancy to adulthood. Studies evaluating progressive loss of lung function, the best-studied measure of asthma progression, are also reviewed, followed by a brief discussion of whether asthma progression can be modified by inhaled glucocorticoid therapy.

Airway responsiveness in mild to moderate childhood asthma: sex influences on the natural history

RATIONALE

Airway responsiveness is a prognostic marker for asthma symptoms in later life.

OBJECTIVES

To evaluate characteristics responsible for persistence of airway responsiveness in children with asthma.

METHODS

A total of 1,041 children, initially aged 5-12 years, with mild to moderate persistent asthma enrolled in the Childhood Asthma Management Program (CAMP) were studied prospectively for 8.6 +/- 1.8 years with methacholine challenges yearly.

MEASUREMENTS AND MAIN RESULTS

Least squares geometric mean models were fit to determine effects of sex and age on airway responsiveness (provocative concentration producing 20% decrease in FEV(1) [PC(20)]). Multiple linear regression analysis was performed to determine factors at baseline and over time, which were associated with PC(20) at end of follow-up. A total of 7,748 methacholine challenges were analyzed. PC(20) increased with age, with boys having greater increase after age 11 years than girls (P < 0.001). The divergence coincided with the mean age for Tanner stage 2. Postpubertal girls had greater airway responsiveness, even after adjustment for FEV(1) and other potential confounders. Although multivariable regression analyses noted a variety of factors that influenced airway responsivness in both sexes, a history of hay fever (beta= -0.30, P = 0.005), respiratory allergy (beta= -0.32, P = 0.006), or recent inhaled corticosteroid usage (beta= -0.18, P = 0.02) were associated with decrements in final log PC(20) only in girls.

CONCLUSIONS

Airway responsiveness (PC(20)) is more severe in the postpubertal female with asthma than in males. Although there are factors associated with airway responsiveness in both males and females, sex-specific factors may contribute to new insights into asthma pathogenesis.

The challenge of asthma in adolescence

The adolescents with asthma are a distinct group of patients with different problems and needs compared to children and adults. Specific issues of asthma in adolescence are the variability of the clinical spectrum, the presence of particular risk factors for the persistence of symptoms, underdiagnosis and undertreatment of the disease. Refusal of the sick role, denial of symptoms, carelessness about dangerous inhalation exposure, erratic self-medication, overexertion without taking precautions against exercise-induced asthma, and a poor relationship between patients, their families, and often doctors are the main obstacles to successful management of asthma in this critical age. There are also major problems of compliance for these patients. The goal of optimal quality of life will be achieved only if the physician thoroughly understands the adolescent's needs and provides optimal care.

Relationship between air pollution, lung function and asthma in adolescents

BACKGROUND

The interrelationships between air pollution, lung function and the incidence of childhood asthma have yet to be established. A study was undertaken to determine whether lung function is associated with new onset asthma and whether this relationship varies by exposure to ambient air pollutants.

METHODS

A cohort of children aged 9-10 years without asthma or wheeze at study entry were identified from the Children's Health Study and followed for 8 years. The participants resided in 12 communities with a wide range of ambient air pollutants that were measured continuously. Spirometric testing was performed and a medical diagnosis of asthma was ascertained annually. Proportional hazard regression models were fitted to investigate the relationship between lung function at study entry and the subsequent development of asthma and to determine whether air pollutants modify these associations.

RESULTS

The level of airway flow was associated with new onset asthma. Over the 10th-90th percentile range of forced expiratory flow over the mid-range of expiration (FEF(25-75), 57.1%), the hazard ratio (HR) of new onset asthma was 0.50 (95% CI 0.35 to 0.71). This protective effect of better lung function was reduced in children exposed to higher levels of particulate matter with an aerodynamic diameter <2.5 microm (PM(2.5)). Over the 10th-90th percentile range of FEF(25-75), the HR of new onset asthma was 0.34 (95% CI 0.21 to 0.56) in communities with low PM(2.5) (<13.7 microg/m(3)) and 0.76 (95% CI 0.45 to 1.26) in communities with high PM(2.5) (> or = 13.7 microg/m(3)). A similar pattern was observed for forced expiratory volume in 1 s. Little variation in HR was observed for ozone.

CONCLUSION

Exposure to high levels of PM(2.5) attenuates the protective effect of better lung function against new onset asthma.

6: Rhinitis and asthma: united airway disease

United airway disease is characterised by inflammation of the respiratory tract, in which asthma and rhinitis are the upper and lower respiratory tract manifestations, respectively, of the same disease process. Irrespective of cause, the upper and lower respiratory tract manifestations are characterised by a systemic inflammatory response. Patients with rhinitis or asthma should always be assessed for coexistent disease in the reciprocal area. Treatment of upper airway disease can modify the severity of lower airway disease and vice versa. The potential for early treatment of allergic rhinitis to prevent progression to asthma merits further study.

Prediction of asthma in young adults using childhood characteristics: Development of a prediction rule

OBJECTIVE

To develop an easily applicable prediction rule for asthma in young adulthood using childhood characteristics.

METHODS

A total of 1,055 out of 1,328 members of a Dutch birth cohort were followed from 2 to 21 years of age. Univariate and multivariate logistic regression analyses were used to evaluate the predictive value of childhood characteristics on asthma at 21 years of age. A prognostic function was developed, and the area under the receiving operating characteristic (ROC) curve was used to estimate the predictive ability of the prognostic models.

RESULTS

Of the 693 responding subjects, 86 (12%) were diagnosed with asthma. Independent prognostic factors at ages 2 and 4 years were female gender (odds ratios (OR) 1.9 and 2.1; 95% confidence intervals (CI) 1.2-3.2 and 1.3-2.5), smoking mother (OR 1.6 and 1.6; CI 1.0-2.7 and 1.0-2.6), lower respiratory tract illness (OR 1.9 and 2.4; CI 1.0-3.6 and 1.4-4.0), and atopic parents (OR 2.1 and 1.9; CI 1.3-3.4 and 1.2-3.1). The predictive power of both models was poor; area under ROC curve was 0.66 and 0.68, respectively.

CONCLUSION

Asthma in young adulthood could not be predicted satisfactorily based on childhood characteristics. Nevertheless, we propose that this method is further tested as a tool to predict development of asthma.

Recurrent childhood upper respiratory tract infections do not reduce the risk of adult atopic disease

BACKGROUND

Children of large families and those attending day care are at increased risk of respiratory tract infections, which in turn may protect against the development of allergic disease. Longitudinal studies investigating these associations beyond childhood are, however, scarce.

OBJECTIVE

To investigate the association between childhood recurrent upper respiratory tract infections (URTI) and asthma, allergic rhinitis (AR) and eczema in adulthood.

METHODS

A birth cohort of 1055 members followed prospectively from the ages of 2 to 21 years. Detailed information on URTI between the ages of 2 and 4 years was collected at 3 monthly intervals in a standardized interview. At the age of 8 years, a parental questionnaire regarding URTI between the ages of 4 and 8 years was used. The incidence of asthma and atopic disease at the age of 21 years was determined using a standardized questionnaire.

RESULTS

Of the original cohort, 693 (66%) members completed the questionnaire. Children who experienced recurrent URTI before the age of 2 years, between the ages of 2-4 years and between ages of 4 and 8 years were not less likely to have asthma at 21 years of age than children who did not experience recurrent URTI, relative risk (RR) 0.97 (95% confidence interval (CI) 0.65-1.46), RR 1.45 (CI 0.95-2.21) and RR 1.51 (CI 0.97-2.36), respectively. Neither were recurrent URTI associated with a decreased risk of AR, nor eczema at the age of 21 years.

CONCLUSIONS

Recurrent URTI in childhood did not reduce the risk of atopic disease in young adulthood.

Are risk factors of childhood asthma predicting disease persistence in early adulthood different in the developing world?

BACKGROUND

Predictive factors of childhood asthma for favorable prognosis may differ between populations where a variety of genetic and environmental factors are present.

OBJECTIVES

To document the factors predicting disease persistence in early adulthood in Turkey.

METHODS

An outpatient cohort (n = 115) with a mean follow-up duration of 11.4 +/- 0.2 years was evaluated. Complete remission was defined as no asthma symptoms, no use of controller medication, no airflow limitation and no airway hyper-responsiveness, and clinical remission as no symptoms and no use of controller medication, within the past year.

RESULTS

The mean ages during referral and at the final visit were 5.8 +/- 0.2 and 17.1 +/- 0.2 years, respectively. Thirty-one (27%) were in complete remission, and a further 30 (26%) in clinical remission. In multivariate logistic models, diminished airflow [forced expiratory volume in 1 s (FEV1) < 80% vs > or = 80%] at the initial lung function test predicted current diminished airflow (8.422; 2.202-32.206) (odds ratio; 95% confidence interval), and presence of obstructive pattern (FEV1/forced vital capacity (FVC) < 80% vs > or = 80%) predicted current obstructive pattern (29.333; 3.022-284.724). Furthermore, female gender appeared to predict persistence of asthma symptoms (3.330; 1.250-8.333) and absence of clinical remission (2.398; 1.038-5.254); eosinophilia predicted persistence of symptoms (4.271; 1.080-16.889) and presence of airway hyper-responsiveness (3.723; 1.129-12.278).

CONCLUSIONS

Diminished airflow, female gender and eosinophilia appear to predict an adverse outcome of childhood asthma, supporting the concept that variability may exist between populations.

Asthma during the primary school ages--prevalence, remission and the impact of allergic sensitization

BACKGROUND

Childhood is the most important time for asthma development. The aims of this study were to study changes in prevalence of asthma and wheeze, remission of asthma and changes in risk factor pattern from age 7-8 to age 11-12 in a cohort of school children.

METHODS

In 1996, 3525 children aged 7-8 years in northern Sweden were invited to participate in a parental expanded ISAAC questionnaire survey. The cohort has been followed prospectively with yearly follow-ups to age 11-12, with a 97% yearly response rate. Skin prick tests were conducted at age 7-8 and 11-12.

RESULTS

The prevalence of physician-diagnosed asthma increased from 5.7% at age 7-8 to 7.7% at age 11-12. Life-time prevalence of wheeze was 34.7% at age 11-12. The remission of asthma was 10% yearly and inversely related to allergic sensitization. Relapses were common, and remission persisting throughout the observation period was 5% yearly. Allergic sensitization was associated with current asthma at age 7-8 [adjusted odds ratio (OR) 4.9 (95% confidence interval (CI) 3.3-7.3)] and when the children were 4 years older [OR 5.6 (3.9-8.2)]. A family history of asthma was associated with current asthma at age 7-8 [OR 3.0 (2.1-4.5)] and 11-12 (OR 2.8 [2.0-3.9]). Ever having lived with a cat was significantly negatively associated with current asthma.

CONCLUSIONS

The prevalence of asthma increased continuously during the primary school ages. Among several significant risk factors, allergic sensitization and a family history of asthma were the most important. With increasing age many known risk factors lost significance. Remission was inversely related to allergic sensitization.

Environmental factors and gene-environment interactions in the aetiology of asthma

The importance of early life environmental influences on the aetiology of asthma is implied by the observed geographic and temporal variation in the prevalence of the disease among children. 2. There is evidence pointing to the role of exposure to allergen, various aspects of diet and hygiene-related factors in the aetiology of asthma. 3. There is also evidence that heritable factors influence the impact of hygiene-related exposures on the risk of having asthma. Polymorphism within genes coding for the toll-like receptor-lipopolysaccharide (TLR-LPS) signalling pathway may underlie variations in effects of hygiene-related exposures, including specifically endotoxin, on the risk of developing allergic sensitization and allergic disease. 4. At present there is no unifying theory to explain the childhood origins of asthma and, hence, no solid basis for developing preventative interventions. Progress towards this goal requires better understanding of the heterogeneous nature of the disease in early childhood, improved characterization of relevant environmental exposures and long-term follow up of birth cohorts with reliable and valid measures of allergy and asthma outcomes.

Risk factors for onset of asthma: a 12-year prospective follow-up study

BACKGROUND

Asthma development and prognosis have been studied extensively in at-risk populations, but knowledge of the natural history of asthma in the general population is limited.

OBJECTIVE

To describe the incidence and remission of asthma and its predictors, data from a 12-year follow-up study of a random population sample (n = 291; age range, 7 to 17 years) at enrollment, were analyzed.

METHODS

The sample was examined in 1986 and in 1998. A case history, including data on asthma, allergic diseases, and lifestyle factors, was obtained by questionnaire and interview. Airway hyperresponsiveness (AHR) to histamine, lung function, and skin-prick test reactivity to a standard panel of 10 aeroallergens were measured.

RESULTS

The point prevalence of asthma increased from 4.1% at the first survey to 11.7% at follow-up, at which point 19.6% of the sample had ever experienced asthma symptoms. Of the subjects with ever-asthma, 40% had remitted at follow-up. Asthma developed in 45 subjects (16.1%) during the follow-up period, which was predicted by the following factors: wheezing in childhood (odds ratio [OR], 3.61; 95% confidence interval [CI], 1.34 to 9.75), AHR (OR, 4.94; 95% CI, 2.42 to 10.08), allergic sensitization to house dust mites (OR, 3.23; 95% CI, 1.00 to 10.40), and dermatitis (OR, 2.94; 95% CI, 1.22 to 7.11). The simultaneous presence of more than one of these risk factors was associated with a high probability of developing asthma at follow-up (61.5%). In subjects without any risk factors, such as AHR, allergic sensitization, rhinitis, dermatitis or wheezing in childhood; paternal/maternal allergy, or asthma, asthma developed in only 4% during follow-up.

CONCLUSION

The presence of AHR and concomitant atopic manifestations in childhood increase the risk of developing asthma in adulthood, and should be recognized as markers of prognostic significance, whereas the absence of these manifestations predicts a very low risk of future asthma.

Outcome in adulthood of asymptomatic airway hyperresponsiveness to histamine and exercise-induced bronchospasm in childhood

BACKGROUND

Studies of the clinical outcome in adulthood of asymptomatic airway hyperresponsiveness (AHR) to histamine or exercise-induced bronchospasm (EIB) detected in childhood in general population samples are sparse and have produced conflicting results.

OBJECTIVE

To describe the outcome of asymptomatic AHR to histamine and EIB.

METHODS

Data from a 12-year follow-up study of a random population sample of individuals aged 7 to 17 years at enrollment were analyzed; only individuals without asthma at enrollment were included in the analysis. AHR to inhaled histamine, EIB, lung function, and sensitization to aeroallergens were measured.

RESULTS

Among the 281 nonasthmatic participants studied, 58 (22%) had AHR to histamine, 33 (12%) had EIB, and 82 (29%) had AHR to histamine and/or EIB. At follow-up, 37.9% of individuals with AHR to histamine and 30% of individuals with EIB had developed current asthma, compared with only 5% of individuals in whom these test results were negative. In patients with AHR to histamine, parental asthma (odds ratio [OR], 12.6; 95% confidence interval [CI], 1.5-108.5), furred pets ownership (OR, 6.0; 95% CI, 1.2-19.6), and dermatitis and/or rhinitis in childhood (OR, 2.2; 95% CI, 1.1-5.1) predicted the subsequent development of asthma, whereas no risk factors for the development of asthma could be identified in individuals with EIB CONCLUSION: Asymptomatic AHR to histamine and EIB in childhood predict the subsequent development of asthma in adulthood. A genetic disposition to asthma, furred pets ownership, and concomitant rhinitis or dermatitis increase the risk of asthma development in individuals with AHR to histamine.

Determinants of asthma and its clinical course

OBJECTIVE

To examine factors that influence the natural history of asthma, such as genetics, atopy, air pollution and environmental tobacco smoke, gastroesophageal reflux, and infection, to promote early identification and treatment of patients at risk for persistent asthma.

DATA SOURCES

Journal articles published in English involving human subjects with asthma.

STUDY SELECTION

Studies were selected for their relevance to the discussion of asthma and the factors that contribute to its persistence. Epidemiologic studies were favored in assessing the natural history of asthma from childhood to adulthood.

RESULTS

Major factors that can influence the severity and persistence of asthma are genetics, atopy, pollution, environmental tobacco smoke, gastroesophageal reflux, and respiratory infections. Epidemiologic studies reveal that factors strongly linked to the persistence of childhood asthma into adult life are early age of disease onset with more severe symptoms, atopy, and level of allergen exposure.

CONCLUSIONS

Although there is still much research to be done, epidemiologic studies have repeatedly proven that the natural history of asthma is in some ways predictable. Early identification of patients at risk for persistent asthma, combined with early institution of pharmacologic and nonpharmacologic intervention strategies, may lead to better outcomes.