Out of the mouths of babes and sucklings: lessons from early childhood asthma

Two Sides of the Same Coin?-Treatment of Chronic Asthma in Children and Adults

Globally, asthma is one of the most common chronic conditions that affect individuals of all ages. When poorly controlled, it negatively impacts patient's ability to enjoy life and work. At the population level, effective use of recommended strategies in children and adults can reduce symptom burden, improve quality of life and significantly reduce the risk of exacerbation, decline of lung function and asthma-related death. Inhaled corticosteroid as the initial maintenance therapy, ideally started within 2 years of symptom onset, is highly effective in both children and adults and across various degrees of asthma severity. If asthma is not controlled, the choice of subsequent add-on therapies differs between children and adults. Evidence supporting pharmacological approach to asthma management, especially for those with more severe disease, is more robust in adults compared to children. This is, in part, due to various challenges in the diagnosis of asthma, in the recruitment into clinical trials and in the lack of objective outcomes in children, especially those in the preschool age group. Nevertheless, where evidence is emerging for younger children, it seems to mirror the observations in adults. Clinicians need to develop strategies to implement guideline-based recommendations while taking into consideration individual variations in asthma clinical phenotypes, pathophysiology and treatment responses at different ages.

Predictors of repeated acute hospital attendance for asthma in children: A systematic review and meta-analysis

BACKGROUND

Asthma attacks are common and have significant physical, psychological, and financial consequences. Improving the assessment of a child's risk of subsequent asthma attacks could support front-line clinicians' decisions on augmenting chronic treatment or specialist referral. We aimed to identify predictors for emergency department (ED) or hospital readmission for asthma from the published literature.

METHODS

We searched MEDLINE, EMBASE, AMED, PsycINFO, and CINAHL with no language, location, or time restrictions. We retrieved observational studies and randomized controlled trials (RCT) assessing factors (personal and family history, and biomarkers) associated with the risk of ED re-attendance or hospital readmission for acute childhood asthma.

RESULTS

Three RCTs and 33 observational studies were included, 31 from Anglophone countries and none from Asia or Africa. There was an unclear or high risk of bias in 14 of the studies, including 2 of the RCTs. Previous history of emergency or hospital admissions for asthma, younger age, African-American ethnicity, and low socioeconomic status increased risk of subsequent ED and hospital readmissions for acute asthma. Female sex and concomitant allergic diseases also predicted hospital readmission.

CONCLUSION

Despite the global importance of this issue, there are relatively few high quality studies or studies from outside North America. Factors other than symptoms are associated with the risk of emergency re-attendance for acute asthma among children. Further research is required to better quantify the risk of future attacks and to assess the role of commonly used biomarkers.

Temporal stability of multitrigger and episodic viral wheeze in early childhood

The distinction between episodic viral wheeze (EVW) and multitrigger wheeze (MTW) is used to guide management of preschool wheeze. It has been questioned whether these phenotypes are stable over time. We examined the temporal stability of MTW and EVW in two large population-based cohorts.We classified children from the Avon Longitudinal Study of Parents and Children (n=10 970) and the Leicester Respiratory Cohorts ((LRCs), n=3263) into EVW, MTW and no wheeze at ages 2, 4 and 6 years based on parent-reported symptoms. Using multinomial regression, we estimated relative risk ratios for EVW and MTW at follow-up (no wheeze as reference category) with and without adjusting for wheeze severity.Although large proportions of children with EVW and MTW became asymptomatic, those that continued to wheeze showed a tendency to remain in the same phenotype: among children with MTW at 4 years in the LRCs, the adjusted relative risk ratio was 15.6 (95% CI 8.3-29.2) for MTW (stable phenotype) compared to 7.0 (95% CI 2.6-18.9) for EVW (phenotype switching) at 6 years. The tendency to persist was weaker for EVW and from 2-4 years. Results were similar across cohorts.This suggests that MTW, and to a lesser extent EVW, tend to persist regardless of wheeze severity.

Infantile wheeze: rethinking dogma

Wheeze is a common symptom in young children and is usually associated with viral illnesses. It is a major source of morbidity and is responsible for a high consumption of healthcare and economic resources worldwide. A few children have a condition resembling classical asthma. Rarer specific conditions may have a wheezy component and should be considered in the differential diagnosis. Over the last half century, there have been many circular discussions about the best way of managing preschool wheeze. In general, intermittent wheezing should be treated with intermittent bronchodilator therapy, and a controller therapy should be prescribed for a young child with recurrent wheezing only if positively indicated, and only then if carefully monitored for efficacy. Good multidisciplinary support, attention to environmental exposition and education are essential in managing this common condition. This article analyses the pathophysiological basis of wheezing in infancy and critically discusses the evolution of the scientific progress over time in this unique field of respiratory medicine.

The effect of respiratory tract infections on reported asthma symptoms

Background: Wheezing and chest tightness is associated with respiratory tract infections. Thus the occurrence of respiratory tract infections may infl uence the prevalence of asthma. Aims: To assess the strength of relation between two main symptoms of asthma and the prevalence of respiratory tract infections in children with and without asthma. Methods: The study population was 3,796 children, four years of age, whose parents had answered a questionnaire on respiratory symptoms and asthma. The prevalence of wheezing and chest tightness in the last 12 months and four weeks was estimated according to the occurrence of respiratory tract infections during the corresponding time periods; 95% confi dence intervals of the prevalence and the statistical signifi cance of the differences in the prevalence by using chi-square test were calculated. Results: The prevalence of wheezing and chest tightness was higher in children who had experienced respiratory tract infections than in those who had not. The prevalence of wheezing was 17.5% among children who had experienced bronchitis and 3.0% among children whom had not ( p<0.001). The prevalence of chest tightness in the last 12 months was 3.7% (95% CI 3.1- 4.1) among children without asthma and 59.3% (95% CI 53.4- 65.2) among children with asthma ( p<0.001). The prevalence of wheezing and chest tightness increased with increasing number of different types of respiratory tract infections among children without asthma ( p<0.001) and tended to be so among children with asthma. Conclusions: These findings have implications for the interpretation of results from epidemiological studies using respiratory symptoms as a health-related outcome of asthma.

Leukotriene receptor antagonists in virus-induced wheezing : evidence to date

Virus-induced wheezing is a relatively benign entity that is usually transient in early childhood but is responsible for much health care utilization. The condition, seen traditionally as a subset of those children diagnosed as having frequent episodic asthma, is often treated with inhaled corticosteroids, despite their lack of efficacy. However, there remains some confusion differentiating atopic asthma from virus-induced wheezing in young children and their respective treatment strategies.The demonstration of cysteinyl leukotrienes in the nasopharyngeal secretions of infants and young children who wheeze prompted investigation of the role of leukotriene receptor antagonists in the treatment of virus-induced wheezing for young children with bronchiolitis and virus-induced wheezing.Montelukast, the only leukotriene receptor antagonist studied in young children, has been proven useful in increasing the number of symptom-free days and delaying the recurrence of wheeze in the month following a diagnosis of respiratory syncytial virus-induced wheezing in children aged 3-36 months. Subsequently, in children aged 2-5 years with frequent episodic asthma, primarily involving viral induced attacks in this age group, regular therapy with daily montelukast for 12 months reduced the rate of asthma exacerbations by 31% over placebo, delayed the time to the first exacerbation by 2 months, and lowered the need to prescribe inhaled corticosteroids as preventative therapy. Additionally, montelukast has been demonstrated to be efficacious as an acute episode modifier in children aged 2-14 years (85% children <6 years) with virus-induced wheezing where it was prescribed at the onset of a viral infection in children with an established pattern of viral induced episodes of wheeze in the preceding year. In this study, emergency department visits were reduced by 45%, visits to all health care practitioners were reduced by 23%, and time of preschool/school and parental time off work was reduced by 33% for children who took montelukast for a median of 10 days.At present, there is good evidence to support the use of bronchodilators in the acute treatment of virus- induced wheezing, and increasing evidence to support the use of leukotriene receptor antagonists, in particular montelukast, in the management of children with virus-induced wheezing.

Leukotriene receptor antagonists as maintenance and intermittent therapy for episodic viral wheeze in children

BACKGROUND

Episodic viral wheeze (EVW) associated with viral respiratory tract infections is a common reason for pre-school children to utilise health care resources and for carers to take time away from employment. About a third of children experience a wheezing episode before the age of five years. EVW therefore represents a significant public health problem. Many pre-school children only wheeze in association with viral infections and in such cases EVW appears to be a separate entity from atopic asthma. Some trials have explored the effectiveness of leukotriene receptor antagonists (LTRAs) as regular (maintenance) or episodic (intermittent) treatment in this context.

OBJECTIVES

To evaluate the evidence for the efficacy and safety of maintenance and intermittent LTRAs in the management of EVW in children aged one to six years.

SEARCH METHODS

We searched the Cochrane Airways Group register of trials with pre-specified terms. We performed additional searches by consulting the authors of identified trials, online trial registries of manufacturers' web sites, and reference lists of identified primary papers and reviews. Search results are current to June 2015.

SELECTION CRITERIA

We included randomised controlled trials with a parallel-group or cross-over (for intermittent LTRA only) design. Maintenance was considered as treatment for more than two months and intermittent as less than 14 days. EVW was defined as a history of at least one previous episode of wheezing in association with a viral respiratory tract infection in the absence of symptoms between episodes. As far as possible, relevant specific data were obtained from authors of studies that included children of a wider age group or phenotype.  

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion in the review and assessed risk of bias. The primary outcome was number of children with one or more viral-induced episodes requiring one or more treatments with rescue oral corticosteroids. We analysed combined continuous data outcomes with the mean difference and dichotomous data outcomes with an odds ratio (OR).

MAIN RESULTS

We identified five studies eligible for inclusion in the review (one investigated maintenance treatment, three intermittent therapy and one had both maintenance and intermittent treatment arms) these included 3741 participants. Each study involved oral montelukast and was of good methodological quality, but differed in choice of outcome measures thus limiting our ability to aggregate data across studies. Only primary outcome and adverse event data are reported in this abstract.For maintenance treatment, specific data obtained from a single study, pertaining to children with only an EVW phenotype, showed no statistically significant group reduction in the number of episodes requiring rescue oral corticosteroids associated with daily montelukast versus placebo (OR 1.20, 95% CI 0.70 to 2.06, moderate quality evidence).For intermittent LTRA, pooled data showed no statistically significant reduction in the number of episodes requiring rescue oral steroids in children treated with LTRA versus placebo (OR 0.77, 95% CI 0.48 to 1.25, moderate quality evidence). Specific data for children with an EVW phenotype obtained from a single study of intermittent montelukast treatment showed a small, but statistically significant reduction in unscheduled medical attendances due to wheeze (RR 0.83, 95% CI 0.71 to 0.98).For maintenance compared to intermittent LTRA treatment no data relating to the primary outcome of the review were identified.There were no other significant group differences identified in other secondary efficacy outcomes for maintenance or intermittent LTRA treatment versus placebo, or maintenance versus intermittent LTRA treatment. We collected descriptive data on adverse events as reported by four of the five included studies, and rates were similar between treatment and placebo groups.Potential heterogeneity in the phenotype of participants within and across trials is a limitation of the evidence.

AUTHORS' CONCLUSIONS

In pre-school children with EVW, there is no evidence of benefit associated with maintenance or intermittent LTRA treatment, compared to placebo, for reducing the number of children with one or more viral-induced episodes requiring rescue oral corticosteroids, and little evidence of significant clinical benefit for other secondary outcomes. Therefore until further data are available, LTRA should be used with caution in individual children. When used, we suggest a therapeutic trial is undertaken, during which efficacy should be carefully monitored. It is likely that children with an apparent EVW phenotype are not a homogeneous group and that subgroups may respond to LTRA treatment depending on the exact patho-physiological mechanisms involved.

Comparison of phenotypes of childhood wheeze and cough in 2 independent cohorts

BACKGROUND

Among children with wheeze and recurrent cough there is great variation in clinical presentation and time course of the disease. We previously distinguished 5 phenotypes of wheeze and cough in early childhood by applying latent class analysis to longitudinal data from a population-based cohort (original cohort).

OBJECTIVE

To validate previously identified phenotypes of childhood cough and wheeze in an independent cohort.

METHODS

We included 903 children reporting wheeze or recurrent cough from an independent population-based cohort (validation cohort). As in the original cohort, we used latent class analysis to identify phenotypes on the basis of symptoms of wheeze and cough at 2 time points (preschool and school age) and objective measurements of atopy, lung function, and airway responsiveness (school age). Prognostic outcomes (wheeze, bronchodilator use, cough apart from colds) 5 years later were compared across phenotypes.

RESULTS

When using a 5-phenotype model, the analysis distinguished 3 phenotypes of wheeze and 2 of cough as in the original cohort. Two phenotypes were closely similar in both cohorts: Atopic persistent wheeze (persistent multiple trigger wheeze and chronic cough, atopy and reduced lung function, poor prognosis) and transient viral wheeze (early-onset transient wheeze with viral triggers, favorable prognosis). The other phenotypes differed more between cohorts. These differences might be explained by differences in age at measurements.

CONCLUSIONS

Applying the same method to 2 different cohorts, we consistently identified 2 phenotypes of wheeze (atopic persistent wheeze, transient viral wheeze), suggesting that these represent distinct disease processes. Differences found in other phenotypes suggest that the age when features are assessed is critical and should be considered carefully when defining phenotypes.

Intermittent or daily montelukast versus placebo for episodic asthma in children

BACKGROUND

No standard, optimal treatment exists for severe intermittent (ie, episodic) asthma in children. However, evidence suggests that both daily and episode-driven montelukast are effective for this phenotype.

OBJECTIVE

To assess the regimen-related efficacy of montelukast in treating pediatric episodic asthma.

METHODS

A multicenter, randomized, double-blind, double-dummy, parallel-group, 52-week study was performed in children 6 months to 5 years of age comparing placebo with two regimens of montelukast 4 mg: (1) daily; or (2) episode-driven for 12 days beginning with signs/symptoms consistent with imminent cold or breathing problem. The main outcome measure was the number of asthma episodes (symptoms requiring treatment) culminating in an asthma attack (symptoms requiring physician visit, emergency room visit, corticosteroids, or hospitalization).

RESULTS

Five hundred eighty-nine patients were randomized to daily montelukast, 591 to intermittent montelukast, and 591 to placebo. Compared with placebo, no significant difference was seen between daily montelukast (P = .510) or intermittent montelukast (P = .884) in the number of asthma episodes culminating in an asthma attack over 1 year. Daily montelukast reduced symptoms over the 12-day treatment period of asthma episodes compared with placebo (P = .045). Beta-agonist use was reduced with both daily (P = .048) and intermittent montelukast (P = .028) compared with placebo. However, because of prespecified rules for multiplicity adjustments (requiring a positive primary endpoint), statistical significance for secondary endpoints cannot be concluded. All treatments were well tolerated.

CONCLUSIONS

Montelukast did not reduce the number of asthma episodes culminating in an asthma attack over 1 year in children 6 months to 5 years of age, although numerical improvements occurred in some endpoints.

Reduced airway function in early adulthood among subjects with wheezing disorder before two years of age

AIM

To compare airway function in early adulthood in subjects with wheezing in infancy with age-matched controls and to analyze what accounts for a possible difference.

METHODS

Asthma development has been prospectively studied in 101 children hospitalized due to wheezing before the age of two. The cohort was re-investigated at age 17-20 years and tested with spirometry and for bronchial hyper-responsiveness and allergic sensitization. An age-matched population (n = 294) was used for comparison.

RESULTS

The cohort had a significantly lower FEV(1)/FVC ratio and MEF(50), both pre- and post-bronchodilation, compared with the controls, P < 0.01. The reduction in airway function was most evident in current asthmatic female subjects, but a reduced pre-bronchodilation FEV(1)/FVC ratio was also seen in symptom-free cohort subjects, P = 0.03. In the multivariate analysis, female gender was the most prominent independent risk factor for reduced airway function in early adulthood, pre-bronchodilation OR 4.0 (1.4-11.3) and post-bronchodilation OR 8.8 (1.8-42.0). In addition, a history of early wheezing, that is, belonging to the cohort, was an independent risk factor for reduced airway function pre-bronchodilation, OR 3.3 (1.3-8.7). Furthermore, there was an association between current bronchial hyper-responsiveness and an increased risk of reduced airway function post-bronchodilation, OR 7.3 (2.0-26.6).

CONCLUSION

Reduced airway function in early adulthood was found in subjects with wheezing early in life, compared with age-matched controls. The reduction was most prominent in females with current asthma.

Respiratory effects of tobacco smoking on infants and young children

Second-hand smoke (SHS) and tobacco smoke products (TSPs) are recognised global risks for human health. The present article reviews the causal role of SHS and TSPs for respiratory disorders in infants and young children. Several studies have shown an effect of TSPs exposure during pregnancy upon lung function in the newborn infant and of SHS on symptoms and lung function after birth. From 1997 to 1999 a set of systematic reviews concerning the relationship between second-hand exposure to tobacco smoke and respiratory health in children was published in Thorax by Cook and Strachan, covering hundreds of published papers. The evidence for a causal relationship between SHS exposure and asthmatic symptoms and reduced lung function is quite strong, whereas the evidence related to the development of allergy is much weaker. There is recent evidence relating to an interaction between TSP exposure and genetic ploymorphisms, demonstrating that certain individuals are more susceptible to the effect of TSP exposure on lung health. In the present review, an overview is given for the effects of TSP exposure and SHS upon lung health in children, with a focus on infants and young children. There is a need for intervention to reduce TSP exposure in young children, by educating parents and adolescents about the health effects of TSP exposure. Recent legislation in many European countries related to smoking in the workplace is of great importance for exposure during pregnancy. Studies are needed to identify possible critical periods for TSPs to induce harmful effects upon lung health in young children and on environment-gene interactions in order to prevent harm.

Two main subtypes of wheezing illness? Evidence from the 2004 Aberdeen schools asthma survey

To compare risk factors for wheezy bronchitis (WB) and multi-trigger wheeze (MTW) in pre-pubertal children along the spectrum of disease severity. Cross-sectional survey of children aged 7-12 yr in Aberdeen city primary schools in 2004 using parent-completed questionnaires as used in surveys in 1964, 1989, 1994, and 1999. Children were grouped into five categories: no wheeze in the past three years, non-severe wheeze triggered only by a cold (non-severe WB), non-severe wheeze triggered by other factors (non-severe MTW), severe WB, or severe MTW. Severe wheeze was defined as greater than four wheezing attacks, greater than or equal to one disturbed night per week, or speech limitation in the last 12 months. Questionnaires were returned by 3271 children (57.3%), of whom 7.4% had WB (6.1% non-severe and 1.3% severe) and 17.2% had MTW (9.4% non-severe and 7.8% severe). Severe disease was more frequent in children with MTW (31.8%) than in those with WB (5.1%). Whereas the prevalence of MTW had increased since 1964, the prevalence of WB had remained stable over this period. After adjustment for confounders, age had no influence on either wheeze type, and male sex was only associated with non-severe WB [OR 1.44, 95% confidence intervals (1.03-2.02)]. In the WB group eczema or/and hay fever in the child were more strongly associated with severe wheeze [OR 3.28(1.49-7.23) vs. OR 1.84(1.31-2.60)]. In the MTW group, this association was noticeably higher than in the WB group, but did not differ much between non-severe and severe wheeze [OR 5.46(3.70-7.20) and OR 6.01(4.1-8.75) respectively]. The presence of any allergic diseases in either parent increased the odds for non-severe and severe MTW at the same level of magnitude [OR 1.92(1.38-2.68) and OR 1.92(1.34-2.76) respectively], and statistically non-significantly for severe WB [OR 1.75(0.78-3.94)]. Living in a deprived area increased both severe WB and severe MTW, reaching statistical significance only for severe MTW [OR 1.96(1.39-2.78)]. Smoking in the house was associated with increased risk of WB and MTW of any severity. WB and MTW differ in prevalence trends and severity. Within severity levels, the influence of age, allergic diseases in children and parents also differed between these two wheezing subtypes.

Early exposure to dichlorodiphenyldichloroethylene, breastfeeding and asthma at age six

Our aims were to assess association of dichlorodiphenyldichloroethylene (DDE) with childhood asthma measured up to age 6 and the effect of DDE on the protective effect of breastfeeding on asthma. In addition, we attempted to assess the relevant time-window of DDE exposure (i.e. at birth or at 4 years). All women presenting for antenatal care in Menorca, Spain over a 12-month period beginning in mid-1997 were invited to take part in a longitudinal study that included a yearly visit. Four hundred eighty-two children were enrolled and 462 provided complete outcome data after 6.5 years of follow-up. Organochlorine compounds were measured in cord serum of 402 (83%) infants and in blood samples of 285 children aged 4. We defined asthma as the presence of wheezing at age 6 and during any preceding year or doctor-diagnosed asthma, and used skin prick test at age 6 to determine atopic status. Results At birth and 4 years of age, all children had detectable levels of DDE (median 1 ng/mL and 0.8 ng/mL, respectively). From birth to age 4, the mean DDE level among children with artificial feeding decreased by 72%, while among breastfed children it increased by 53%. Diagnosed asthma and persistent wheezing were associated with DDE at birth [odds ratio (OR) for an increase in 1 ng/mL, OR=1.18, 95% confidence interval (95% CI)=1.01-1.39 and OR=1.13, 95% CI=0.98-1.30, respectively], but not with DDE at 4 years. Neither breastfeeding nor atopy modified these associations (P>0.3). Breastfeeding protected against diagnosed asthma (OR=0.33, 95% CI=0.08-0.87) and wheezing (OR=0.53, 95% CI=0.34-0.82) in children with low and high DDE levels at birth. Conclusion In a community without known dichlorodiphenyltrichloroethane environmental releases, this study strengthens the evidence for an effect of DDE on asthma by measuring the disease at age 6 and does not support the hypothesis that DDE modifies the protective effect of breastfeeding on asthma.

Short-course montelukast for intermittent asthma in children: a randomized controlled trial

RATIONALE

In children, intermittent asthma is the most common pattern and is responsible for the majority of exacerbations. Montelukast has a rapid onset of action and may be effective if used intermittently.

OBJECTIVES

To determine whether a short course of montelukast in children with intermittent asthma would modify the severity of an asthma episode.

METHODS

Children, aged 2-14 years with intermittent asthma participated in this multicenter, randomized, double-blind, placebo-controlled clinical trial over a 12-month period. Treatment with montelukast or placebo was initiated by parents at the onset of each upper respiratory tract infection or asthma symptoms and continued for a minimum of 7 days or until symptoms had resolved for 48 hours.

MEASUREMENTS AND MAIN RESULTS

A total of 220 children were randomized, 107 to montelukast and 113 to placebo. There were 681 treated episodes (345 montelukast, 336 placebo) provided by 202 patients. The montelukast group had 163 unscheduled health care resource utilizations for asthma compared with 228 in the placebo group (odds ratio, 0.65; 95% confidence interval, 0.47-0.89). There was a nonsignificant reduction in specialist attendances and hospitalizations, duration of episode, and beta-agonist and prednisolone use. Symptoms were reduced by 14% and nights awakened by 8.6% (p = 0.043), and days off from school or childcare by 37% and parent time off from work by 33% (p < 0.0001 for both).

CONCLUSIONS

A short course of montelukast, introduced at the first signs of an asthma episode, results in a modest reduction in acute health care resource utilization, symptoms, time off from school, and parental time off from work in children with intermittent asthma.

Parental smoking and childhood asthma: clinical implications

Environmental tobacco smoke and constituents are global risks for human health. Considerable evidence shows that environmental tobacco smoke exposure contributes to, and exacerbates, respiratory disorders. This review assesses the causal role of environmental tobacco smoke exposure for childhood respiratory disorders, and in particular asthma. Tobacco smoke and environmental tobacco smoke exposure during pregnancy have an effect upon lung function in newborn infants; exposure after birth also has an effect upon lung function. An effect upon bronchial responsiveness has been suggested but the evidence is not as strong as for lung function. From 1997 to 1999 a comprehensive set of systematic reviews concerning the relationship between exposure to environmental tobacco smoke and respiratory health in children summarized the results from hundreds of published papers. The evidence for a causal relationship between environmental tobacco smoke exposure and asthmatic symptoms on the one hand, and between environmental tobacco smoke exposure and reduction in lung function on the other hand, was quite strong, whereas the evidence between environmental tobacco smoke exposure and development of allergy was much weaker. Here we present an overview of the effects of environmental tobacco smoke exposure on lung health in children. A hypothesis has been put forward regarding upregulation of pulmonary neuroendocrine cells in relationship to mechanisms of tobacco smoke products (TSP)-induced pulmonary disease. It has also been reported that genetic variation makes part of the population especially vulnerable to environmental tobacco smoke exposure during pregnancy. Furthermore, there is a need for intervention to reduce environmental tobacco smoke exposure in young children, by educating parents and adolescents about the health effects of environmental tobacco smoke exposure. Studies are needed to identify possible critical periods when environmental tobacco smoke exposure is more likely to induce harmful effects on lung health in young children in order to implement effective preventive strategies.

Efficacy of fluticasone propionate on lung function and symptoms in wheezy infants

The role of inhaled corticosteroids in the treatment of recurrent or persistent wheeze in infancy remains unclear. We evaluated the effect of 3 months of treatment with inhaled fluticasone propionate, 200 microg daily (FP200), on lung function and symptom scores in wheezy infants. Moreover, we evaluated whether infants with atopy and/or eczema respond better to FP200 as compared with non-atopic infants. Forced expiratory flow (Vmax(FRC)) was measured at baseline and after treatment. Sixty-five infants were randomized to receive FP200 or placebo, and 62 infants (mean age, 11.3 months) completed the study. Mean Vmax(FRC), expressed as a Z score, was significantly below normal at baseline and after treatment in both groups. The change from baseline of Vmax(FRC) was not different between the two treatment arms. After 6 weeks of treatment, and not after 13 weeks, the FP200 group had a significantly higher percentage of symptom-free days and a significant reduction in mean daily cough score compared with placebo. Separate analysis of treatment effect in infants with atopy or eczema showed no effect modification. We conclude that in wheezy infants, after 3 months of treatment with fluticasone, there was no improvement in lung function and no reduction in respiratory symptoms compared with placebo.

Validity and reliability of acoustic analysis of respiratory sounds in infants

OBJECTIVE

To investigate the validity and reliability of computerised acoustic analysis in the detection of abnormal respiratory noises in infants.

METHODS

Blinded, prospective comparison of acoustic analysis with stethoscope examination. Validity and reliability of acoustic analysis were assessed by calculating the degree of observer agreement using the kappa statistic with 95% confidence intervals (CI).

RESULTS

102 infants under 18 months were recruited. Convergent validity for agreement between stethoscope examination and acoustic analysis was poor for wheeze (kappa = 0.07 (95% CI, -0.13 to 0.26)) and rattles (kappa = 0.11 (-0.05 to 0.27)) and fair for crackles (kappa = 0.36 (0.18 to 0.54)). Both the stethoscope and acoustic analysis distinguished well between sounds (discriminant validity). Agreement between observers for the presence of wheeze was poor for both stethoscope examination and acoustic analysis. Agreement for rattles was moderate for the stethoscope but poor for acoustic analysis. Agreement for crackles was moderate using both techniques. Within-observer reliability for all sounds using acoustic analysis was moderate to good.

CONCLUSIONS

The stethoscope is unreliable for assessing respiratory sounds in infants. This has important implications for its use as a diagnostic tool for lung disorders in infants, and confirms that it cannot be used as a gold standard. Because of the unreliability of the stethoscope, the validity of acoustic analysis could not be demonstrated, although it could discriminate between sounds well and showed good within-observer reliability. For acoustic analysis, targeted training and the development of computerised pattern recognition systems may improve reliability so that it can be used in clinical practice.

How accurate is diagnosis of asthma in a general practice database? A review of patients' notes and questionnaire-reported symptoms

BACKGROUND

Planned care of patients with chronic diseases in primary care depends on being able to identify them. A recorded label of asthma does not necessarily mean that the patient is currently symptomatic, and failure to record the diagnosis may influence future care.

AIM

To determine the degree of under- and over-reporting of the diagnosis of asthma for patients aged 16-55 years inclusive in one large general practice.

DESIGN

A questionnaire validated for the detection of bronchial hyper-reactivity was sent to all patients recorded as having asthma and their matched controls. Patients with a diagnosis of asthma and symptomatic bronchial hyper-reactivity were considered to have asthma. Evidence of asthma in the written and computer records was sought for two groups: patients with asthma and without symptoms of bronchial hyper-reactivity, and controls with symptoms of bronchial hyper-reactivity.

SETTING

A semi-rural group practice with 14 830 patients.

METHOD

Questionnaires were sent to 833 patients and 831 controls matched by age and sex.

RESULTS

Response rates were 79.1% (659/833)for patients with asthma and 70.6% (587/831) for control patients. Of the patients with asthma who replied, 60.5% (399/659) had symptomatic bronchial hyper-reactivity. Of those with asthma and a negative bronchial hyper-reactivity status (based on the questionnaire), 190/260 (73.1%) were considered to have had asthma when diagnosed, on review of their primary care records. There was no evidence to suggest asthma in 45 (17.3%) of the 260 patients who had a negative bronchial hyper-reactivity status. Of the control patients, 41 (7.0%) of the 587 responders had symptomatic bronchial hyper-reactivity and nine of these may have asthma. By extrapolation, we estimate that there were possibly another 99 patients with symptoms of asthma, who had not been labelled as having asthma, and 362 patients with symptoms of bronchial hyper-reactivity who had not reported them to their doctors or had not had them recognised.

CONCLUSIONS

There is an 89.4% chance that a patient recorded as having asthma has, or has had, asthma.

Is bronchodilator response in 2-yr-old children associated with asthma risk factors?

Factors that might influence lung function bronchodilator response by 2 yr of age is largely unknown, thus we aimed to assess this in the 'Environment and Childhood asthma' (ECA) study in Oslo. A clinical investigation at mean age 26 months was attended by 516 (84%) children included in a nested case-control study [children with recurrent bronchial obstruction (rBO)] (n = 265) and controls without a history of lower respiratory disease (n = 251). Tidal lung function measures before and after inhaled nebulized salbutamol (bronchodilator response) (when clinically without BO) were obtained in 46%. Clinical characteristics and personal and family history of allergic/respiratory diseases (asthma risk factors) were ascertained by structured interview and clinical examination. Allergic sensitization was assessed by skin prick test/specific IgE antibody analyses to common allergens. Mean (95% CI) per cent change in time to reach peak flow/total expiratory time (t(PTEF)/t(E)) from before to after salbutamol was significantly larger in children with rBO [17.3 (9.4-25.3) than controls (-2.2 (-7.7 to 3.0)]. The bronchodilator response increased significantly (p = 0.001) with increasing number of asthma risk factors, but was not significantly associated with allergic sensitization, parental 'atopy', or maternal smoking alone. Children treated with inhaled corticosteroids had greater bronchodilator response than those treated with bronchodilators alone. Bronchodilator response in asymptomatic 2-yr-old children was most closely associated with the presence of rBO, but increasing number of asthma risk factors and treatment with inhaled corticosteroids were associated with increased bronchodilator response.

The effect of parental smoking on lung function and development during infancy

While the adverse effects of parental smoking on respiratory health during childhood are well recognized, its potential impact on early lung development is less clear. This review summarizes current evidence on the effect of parental smoking on lung function during infancy. It is difficult to separate the effects of pre- and postnatal exposure, since the majority of mothers who smoke in pregnancy (currently around 30% worldwide) continue to do so thereafter. Nevertheless, measurements undertaken prior to any postnatal exposure have consistently demonstrated significant changes in tidal flow patterns in infants whose mothers smoked in pregnancy. While there is, as yet, no convincing evidence from studies in human infants that smoking during pregnancy is associated with increased airway responsiveness at birth, many studies have demonstrated a reduction in forced expiratory flows (on average by 20%) in infants exposed to parental smoking. While maternal smoking during pregnancy remains the most significant source of such exposure and is likely to be responsible for diminished airway function in early life, continuing postnatal tobacco smoke exposure will increase the risk of respiratory infections, the combination of both being responsible for the two- to fourfold increased risk of wheezing illnesses observed during the first year of life in infants whose parents smoke. These findings emphasize the need to keep infants in a smoke-free environment both before and after birth, not least because of growing awareness that airway function in later life is largely determined by that during foetal development and early infancy.

Wheezy bronchitis in childhood: a distinct clinical entity with lifelong significance?

BACKGROUND

Historically, clinicians have recognized the existence of the clinical syndrome of childhood wheezy bronchitis. In the late 1960s, children with this syndrome were relabeled as having asthma, and the term wheezy bronchitis was abandoned. In a 1989 study of a cohort that originally had been studied in 1964, we reported that those who had childhood wheezy bronchitis had as adults attained lung function similar to that of healthy control subjects and had less significant symptoms than did those who had experienced childhood asthma, in whom lung function was reduced. In this study, we reexamined these subjects 12 years later to determine whether the improved outcome of the wheezy bronchitis group had been maintained.

METHODS

In 2001, we followed up the 283 participants of the 1989 study, who were now aged 45 to 50 years. In interviews, respiratory symptoms and smoking status were assessed. Spirometry was measured.

RESULTS

One hundred seventy-seven subjects (63%) completed the study. After adjusting for age, height, gender, socioeconomic status, smoking status, and number of pack-years smoked, the current FEV(1) in the childhood asthma group (mean, 2.45 L; 95% confidence interval, 2.29 to 2.62) was significantly lower than the wheezy bronchitis group (2.78 L, 95% confidence interval, 2.64 to 2.91; p < 0.01) and the control group (2.96 L; 95% confidence interval, 2.83 to 3.1; p < 0.01). The difference between the wheezy bronchitis group and the control subjects was not significant (p = 0.06). Between 1989 and 2001, both the childhood wheezy bronchitis group (p < 0.01) and the childhood asthma group (p = 0.01) had greater declines in FEV(1) than did the control group (asthma group decline, - 0.75 L [95% confidence interval, - 0.66 to - 0.84]; wheezy bronchitis group decline, - 0.75 L [95% confidence interval, - 0.68 to - 0.83]; control group decline, - 0.59 L [95% confidence interval, - 0.52 to - 0.67]). In 2001, the asthma group had more symptoms than did the wheezy bronchitis group (p < 0.01), who were more symptomatic than the control group (p < 0.01).

CONCLUSION

Those with childhood wheezy bronchitis, having achieved normal lung function in earlier adulthood, now show a more rapid decline in lung function than did control subjects. If this rate of decline persists, these subjects may develop obstructive airways disease in later life.

Episodic viral wheeze in preschool children: effect of topical nasal corticosteroid prophylaxis

BACKGROUND

The effect of prophylactic nasal corticosteroids on wheezing episodes associated with colds was investigated in a 12 week parallel group, double blind, randomised controlled trial in preschool children.

METHODS

Data were collected from 50 children aged 12-54 months with a history of at least three episodes of wheeze associated with colds over the previous winter, but few or no interval symptoms; 24 were given one dose of fluticasone aqueous nasal spray (50 micro g) into each nostril twice daily and 26 received an indistinguishable placebo spray. Episodes of lower respiratory illness occurring within 2 days of the onset of a cold were identified from daily symptom diaries. The main outcome was nocturnal symptom score during the first 7 days of an episode.

RESULTS

The groups were well balanced on entry except that the treatment group had a history of more prolonged episodes. During the trial there was no significant difference in the number of episodes in the treatment and control groups (27 and 37, respectively), in the severity of nocturnal symptoms (mean score 1.33 and 1.22, respectively, confidence interval of difference -0.24 to +0.47) or in daytime symptoms, activity or total scores during episodes. Compliance was estimated to be over 50% in 43 of the children.

CONCLUSIONS

Nasal corticosteroid treatment does not prevent acute wheezy episodes associated with upper respiratory infections (common colds) in preschool children.

The role of house dust mite elimination in the management of childhood asthma: an unresolved issue

Indoor allergens are likely to be direct environmental causes of asthma and mite exposure, and sensitization is the most important environmental risk factor for childhood asthma in temperate zones. Analagous to occupational asthma, allergen avoidance in asthmatic children sensitized and exposed to mite allergens is associated with a reduction in airway hyperresponsiveness and symptoms associated with improvement in lung function. The long-term effect of this strategy needs to be prospectively evaluated considering both the timing and duration of exposure, as well as the timing and duration of removal. In order to be successful, it is important to achieve and maintain a major reduction on allergen levels, for a long period of time.

A model of viral wheeze in nonasthmatic adults: symptoms and physiology

Episodic wheezing associated with viral infections of the upper respiratory tract (URT) is a common problem in young children but also occurs in adults. It is hypothesized that an experimental infection with human coronavirus (HCoV), the second most prevalent common cold virus, would cause lower respiratory tract (LRT) changes in adults with a history of viral wheeze. Twenty-four viral wheezers (15 atopic) and 19 controls (seven atopic) were inoculated with HCoV 229E and monitored for the development of symptoms, changes in airway physiology and provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20). At baseline, viral wheezers were similar to controls in PC20 (mean+/-SD log2PC20: 5.1+/-1.9 and 5.8+/-1.4 g x L(-1), respectively) but had a lower FEV1 than controls (mean+/-SD 85.8+/-11.4 and 95.6+/-13.2% predicted, respectively p < 0.05). Nineteen viral wheezers and 11 controls developed colds. Viral wheezers with colds reported significantly more URT symptoms than controls (median scores (interquartile range): 24 (10-37) and 6 (4-15), respectively p = 0.014). Sixteen viral wheezers and no controls reported LRT symptoms (wheeze, chest tightness and shortness of breath). The viral wheezers with colds had small (3-4%) reductions in FEV1 and peak expiratory flow on days with LRT symptoms (days 3-6), but a progressive reduction in PC20 from baseline on days 2, 4 and 17 after inoculation (by 0.82, 1.35 and 1.82 doubling concentrations, respectively). The fall in PC20 affected both atopic and nonatopic subjects equally. There were no changes in FEV1 or PC20 in controls. An adult model of viral wheeze that is independent of atopy and therefore, of classical atopic asthma was established.

Are all wheezing disorders in very young (preschool) children increasing in prevalence?

BACKGROUND

Distinct wheezing disorders co-exist in young (preschool) children, some of which (early transient wheeze and viral wheeze) are thought to be unrelated to atopy. Investigation of changes in prevalence of wheezing disorders in preschool children could provide important clues about underlying mechanisms responsible for increasing prevalence of asthma in schoolchildren.

METHODS

Repeated population surveys of the prevalence of respiratory symptoms were done by parent-completed postal questionnaires in random samples of 1650 (1990) and 2600 (1998) caucasian children aged 1-5 years living in the county of Leicestershire, UK.

FINDINGS

The response rates were 86% (1422 of 1650) in 1990 and 84% (2127 of 2522) in 1998. Between 1990 and 1998, there was a significant increase in the prevalance of reported wheeze ever (16% to 29%, p<0.0001), current wheeze (12% to 26%, p<0.0001), diagnosis of asthma (11% to 19%, p<0.0001), treatment for wheeze (15% to 26%, p<0.0001), and admission for wheeze or other chest trouble (6% to 10%, p<0.0001). The increase occurred both in children with viral wheeze (9% to 19%) and in those with the classic asthma pattern of wheezing with multiple triggers (6% to 10%). There was also an increase in transient early wheezers (3% to 5%), persistent wheezers (5% to 13%), and late-onset wheezers (6% to 8%), and in all severity groups. The increase could not be accounted for by putative household risk factors because these declined between the 2 years.

INTERPRETATION

The fact that all preschool wheezing disorders increased (including viral wheeze) makes it probable that factors unrelated to atopy are implicated in the changing epidemiology of wheeze in childhood.

Genetic/environmental determinants of adult chronic obstructive pulmonary disease and possible links with childhood wheezing

Epidemiological evidence and similarities in underlying inflammatory mechanisms suggest that childhood respiratory conditions and adult onset chronic obstructive pulmonary disease (COPD) may have a common aetiology. The prevalence of COPD in the UK has been estimated to be 10% in males and 11% in females, and like asthma, is thought to have a polygenic contribution with a complex interplay between genetic and environmental factors. The only proven genetic factor so far identified in its pathogenesis is alpha1-antitrypsin deficiency, although this accounts for less than 1% of individuals with disease. Environmental exposures are significant but the observation that only 15% of smokers develop COPD and only some young children exposed in utero develop recurrent wheezing points to as yet undefined contributory genetic factors. The similarity in response to medication also suggests some features in common and a central question must be whether those adults who develop COPD had transient viral-associated wheeze (VAW) or non-specific bronchial hyperresponsiveness (BHR) in childhood? Similarities between some of the childhood wheezing syndromes and adult onset COPD invites a re-examination of possible links between the two conditions.

In utero and perinatal complications preceding asthma

BACKGROUND

It has been suggested that pregnancy and early life may influence the development of asthma in the offspring, but published studies have not carefully controlled for potential biases.

METHODS

In a large British birth cohort of 4065 natural children of 2583 mothers, we investigated whether in utero and perinatal influences contribute to the development and the severity of asthma in childhood, allowing for possible confounders of the relationship, and considering the nonindependence of familial data.

RESULTS

Child asthma (10.1%) was more frequently reported by mothers when there had been health complications during pregnancy (prevalence =14.3%; adjusted odds ratio [ORadj] =2.01; 95% confidence interval, 1.52-2.67), labor, or delivery (19.3%, ORadj =1.35, 1.01-1.81); child illness or health complications during the first week of life (22.6%, ORadj =1.35, 1.01-1.82); and birth weight of < 2.5 kg (7.0%, ORadj =1.57, 1.10-2.25). Specific causes of health complications during pregnancy which significantly related to asthma were early or threatened labor (ICD: 644) (4.8%, ORadj =1.58, 1.03-2.40) and the malposition or malpresentation of the fetus (ICD: 652) (1.6%, ORadj =3.63, 1.47-8.91).

CONCLUSION

The results provide further evidence that in utero and perinatal factors may increase the risk of developing asthma.

Cross-sectional observations on the natural history of asthma

BACKGROUND

Asthma is a major health care problem that affects all ages. It is uncertain whether asthma is a single clinical entity or a grouping of separate clinical syndromes that share a common set of treatment guidelines.

AIM

To observe the symptoms, treatment step, and health service utilisation of a population of patients throughout the United Kingdom (UK) listed on an asthma register.

DESIGN OF STUDY

A cross-sectional study and clinical assessment of asthma patients.

SETTING

A total of 12,203 patients from 393 general practices throughout the UK.

METHOD

A database was used to observe the symptoms, treatment step, and health service utilisation of the asthma patients.

RESULTS

Children aged up to four years had a distinctive profile of symptoms, including night time cough. They also experienced increased health service utilisation including a high hospital admission rate. Symptoms in adults became more common with increasing age. The pattern of symptoms in patients aged 45 years and over suggest many patients on asthma registers may have chronic obstructive pulmonary disease. Patients aged 16 to 30 years showed a different pattern of health service usage to those aged 5 to 15 years and 31 to 45 years, relying more on unscheduled use of health services rather than a review-based management plan. Patients aged 16 to 30 years used less anti-asthma medication than those aged 5 to 15 years and 31 to 45 years.

CONCLUSIONS

Databases may be a useful tool with which to study the natural history of asthma, but there are problems with bias. Several clinical subgroups exist within the broad diagnosis label of asthma. Knowledge of how these subgroups of doctor-diagnosed asthma use health services may help clinicians to create individual care plans for groups of patients.

Daycare attendance, asthma and atopy

The objective of this article is to review studies that have examined the relation of daycare to asthma and atopy. In order to identify studies for inclusion, abstracts of all studies referenced in Medline from January 1966 to January 2000 and in BIBSYS were searched and extracted if they included 'asthma' or 'atopy' combined with words such as 'daycare', 'nursery' or 'kindergarten'. Eight studies fulfilled the criteria of inclusion. The outcomes were asthma, skin prick test (SPT) reactivity, a positive radioallergosorbent test (RAST), hay fever, and eczema. Daycare attendance was positively associated with asthma in five of six studies including asthma. In three of these studies there was no statistically significant association between daycare and asthma. Early start in daycare protected against later asthma in one study. There was a weak, but not a statistically significant positive relation between daycare and atopy in two of three studies when SPT reactivity was used as the outcome. In children of small families early start in daycare protected against atopy. The quality of the studies varies, and they are not directly comparable. The relation between daycare attendance and asthma and atopy is unclear, and further studies designed to answer this specific research question are needed.

Siblings, day-care attendance, and the risk of asthma and wheezing during childhood

BACKGROUND

Young children with older siblings and those who attend day care are at increased risk for infections, which in turn may protect against the development of allergic diseases, including asthma. However, the results of studies examining the relation between exposure to other children and the subsequent development of asthma have been conflicting.

METHODS

In a study involving 1035 children followed since birth as part of the Tucson Children's Respiratory Study, we determined the incidence of asthma (defined as at least one episode of asthma diagnosed by a physician when the child was 6 to 13 years old) and the prevalence of frequent wheezing (more than three wheezing episodes during the preceding year) in relation to the number of siblings at home and in relation to attendance at day care during infancy.

RESULTS

The presence of one or more older siblings at home protected against the development of asthma (adjusted relative risk for each additional older sibling, 0.8; 95 percent confidence interval, 0.7 to 1.0; P=0.04), as did attendance at day care during the first six months of life (adjusted relative risk, 0.4; 95 percent confidence interval, 0.2 to 1.0; P=0.04). Children with more exposure to other children at home or at day care were more likely to have frequent wheezing at the age of 2 years than children with little or no exposure (adjusted relative risk, 1.4; 95 percent confidence interval, 1.1 to 1.8; P=0.01) but were less likely to have frequent wheezing from the age of 6 (adjusted relative risk, 0.8; 95 percent confidence interval, 0.6 to 1.0; P=0.03) through the age of 13 (adjusted relative risk, 0.3; 95 percent confidence interval, 0.2 to 0.5; P<0.001).

CONCLUSIONS

Exposure of young children to older children at home or to other children at day care protects against the development of asthma and frequent wheezing later in childhood.

Issues and unmet needs in pediatric asthma

Asthma is common and becoming more so in childhood. Although mild asthma may incur low average annual costs per child, these estimates need to be viewed in the context of the very large numbers of affected individuals. Whereas asthma and wheezing illness in childhood had in the past been broadly subdivided into asthma (often associated with atopy) and wheezy bronchitis (wheeze only, with associated upper respiratory tract infection), this distinction was lost during the 1970s in view of the demonstrated underdiagnosis and undertreatment of symptomatic school-age children. The acceptance of asthma as a chronic inflammatory disease and evidence for airway remodeling and progressive deterioration in airway function in association with symptoms and atopy have led to earlier use of topical steroids at higher starting doses delivered by improved age-appropriate devices. Treating all children as if they were destined to become atopic asthmatics and at risk of airway remodeling may not be rational, particularly in those whose symptoms will subsequently resolve. However, there are as yet no screening tests which can clearly identify individuals at risk of long-term chronic airway inflammation and airway remodeling. The large number of infants and young children with current symptoms suggestive of asthma and in whom resolution is likely in the majority poses problems for the clinician in deciding the best initial therapy. There is an urgent need to develop simple and reliable measures that can identify the early manifestations of atopic airway sensitisation and to establish the place of early intervention with nonsteroidal drugs, including leukotriene antigonists.

Corticosteroid-sparing options in the treatment of childhood asthma

During the last 30 years, a significant rise in wheezing illness has occurred in the child population. Despite its high prevalence there is no clear definition of the disease, which includes a heterogeneous group of syndromes ranging from transient wheezing in infancy to atopic asthma with persistence into adult life. Molecular advances and further epidemiological information from well characterised individuals and their families are likely to clarify the different subtypes of wheezing illness and inform therapeutic options. With the recognition that chronic airway inflammation is a feature of persistent disease, at least in adults, there has been a trend towards the early introduction of anti-inflammatory treatment and particularly inhaled corticosteroids (ICS). However, the natural resolution of much wheezing illness, particularly in young children and in children with viral-induced episodes, suggests that newly presenting children should remain on symptomatic therapy alone while the severity of the disease is being assessed. Although ICS have become a cornerstone of management of chronic persistent disease, their ability to protect against exacerbations in young and mildly affected children is questionable. Alongside concerns about long term use of ICS and possible systemic adverse effects, there remains a need for alternative approaches to the control of the disease in children. Extrapolation of the findings of large multicentre adult studies into childhood, particularly for doubling the doses of ICS and long-acting beta2-agonists, may be unsound. Other approaches include the early introduction of inhaled cromones, use of second generation antihistamines, low dose theophyllines and, more recently, leukotriene modifiers. As the majority of preschool children will become asymptomatic by mid-childhood, there is an urgent need to identify those in whom chronic airway inflammation is developing, as it is in this group that early introduction of ICS may be of maximum benefit. In the remainder, other approaches, including use of corticosteroid-sparing longacting P2-agonists and leukotriene modifying drugs, may be more appropriate. Safe and effective oral preparations such as leukotriene modifying drugs are likely to establish a significant role in the management of symptoms in children of all ages and with all types of asthma and wheezing illness.

Inhaled salbutamol for wheezy infants: a randomised controlled trial

BACKGROUND

Salbutamol is frequently used as a bronchodilator for infants who wheeze. Many single dose studies have questioned its effectiveness.

AIMS

To investigate the response of wheezy infants to salbutamol over an extended time period in order to elucidate either symptomatic relief or a protective effect.

METHODS

Eighty infants under 1 year, with persistent or recurrent wheeze and a personal or family history of atopy, were recruited to a randomised, double blind, cross over, placebo controlled trial. Salbutamol (200 microg three times daily) or placebo were administered regularly over two consecutive treatment periods of four weeks via a spacer and mask. Symptoms of wheeze and cough were recorded in a diary. At the end of the study pulmonary function tests were performed before and after salbutamol (400 microg).

RESULTS

Forty eight infants completed the diary study; 40 infants underwent pulmonary function testing. No difference in mean daily symptom score was observed between the salbutamol and placebo periods. There was no difference in the number of symptom free days. Compliance and forced expiratory flows remained unchanged and resistance increased following salbutamol. There was no relation between the response measured by symptom score or pulmonary function in individual patients.

CONCLUSION

In wheezy infants with an atopic background, there was no significant beneficial effect of salbutamol on either clinical symptoms or pulmonary function. Clinical effects could not be predicted from pulmonary function tests. Salbutamol cannot be recommended as the bronchodilator of choice in this age group.

Differences between infants and adults in the social aetiology of wheeze. The ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood

OBJECTIVES

To compare the relation between relative deprivation, its associated social risk factors and the prevalence of wheeze in infancy and in adulthood.

DESIGN

A cross sectional population study.

SETTING

The three District Health Authorities of Bristol.

SUBJECTS

A random sample of 1954 women stratified by age and housing tenure to be representative of women with children < 1 in Great Britain and selected from the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC).

MAIN OUTCOME MEASURES

The prevalence of wheeze for infants at six months after birth and for their mothers and fathers at eight months postpartum. Potential mediators of the relation between relative deprivation and wheeze measured were overcrowded living conditions, number of other siblings in the household, damp or mouldy housing conditions, maternal and paternal smoking behaviour, and infant feeding practice.

RESULTS

63.4% (1239) of the sample lived in owner occupied/mortgaged accommodation (relatively affluent) and 36.6% (715) lived in council house/rented accommodation (relatively deprived). Wheeze was significantly more likely for infants living in council house/rented accommodation (chi 2 = 15.93, df = 1, p < 0.0001), their mothers (chi 2 = 9.28, df = 1, p < 0.001) and their fathers (chi 2 = 7.41, df = 1, p < 0.01). For those living in council house/rented accommodation backward stepwise logistic regression analyses showed that infants with other siblings in the household were significantly more likely to wheeze (OR = 1.83, 95% CI = 1.27, 2.65), as were infants whose mothers smoked (OR = 1.82, 95% CI = 1.30, 2.55) and those who were breast fed for less than three months (OR = 0.66, 95% CI = 0.44, 0.98). Mothers with a partner who smoked were significantly more likely to report wheeze (OR = 1.73, 95% CI = 1.05, 2.85). There was no independent association between the social factors included in the analysis and the likelihood of wheeze for fathers.

CONCLUSIONS

This study identified differences in the social factors associated with a higher prevalence of wheeze in infancy and in adulthood; results suggested that this symptom was commonly linked to infection in infancy, but not in adulthood. While environmental tobacco smoke was associated with a higher prevalence of wheeze in infancy and in adulthood, this does not necessarily indicate a common underlying mechanism; possible explanations are discussed.

The epidemiology of childhood asthma

Variability is the hallmark of childhood asthma. Conceptually defined as variable airflow obstruction, asthma affects individual children through a variety of clinical manifestations. Particular controversy surrounds the nature of wheezing in early infancy and its relationship to atopic asthma of later onset. Asthma prognosis is also highly variable and only to a limited extent predictable by clinical indicators in early childhood. Long-term follow-up studies suggest a complex pattern of remission and relapse as wheezy children are followed through adolescence into adult life. Similarly, the population burden of asthma is highly variable, both over time and between countries. The balance of evidence worldwide suggests a modest but sustained increase in the prevalence of asthma symptoms over the past three decades. Superimposed on this have been larger changes in diagnostic fashion and use of health services for childhood asthma in many countries. There is substantial international variation in the prevalence of asthma symptoms, and marked urban-rural differences have been reported from several African countries. These contrast with the more uniform distribution of the disease within industrialized countries, reflecting its ubiquity in affluent societies.

Perinatal risk factors for recurrent wheeze in early life

The possible value of tidal flow volume (TFV) loops measured at birth in relation to the risk of developing recurrent or persistent bronchial obstruction within two years of life was assessed. TFV loops were measured at a mean age of 2.7 days in 802 neonates enrolled in the 'Environment and Childhood Asthma' (ECA) study in Oslo. Of these, 77 children developed recurrent or persistent bronchial obstruction (cases) and were included in a nested case-control study within the ECA study; 88 controls (the child born closest in time to the case), with no history of bronchial obstruction in the first two years of life, were also included. Information on socio-economic factors, parental atopic diseases and parental smoking habits during the pregnancy was collected from a questionnaire completed by the parents in the maternity ward, and cord blood IgE (CB-IgE) was determined as part of routine sampling in the delivery ward. Mean tPTEF/tE (time to reach peak flow to total expiratory time) was slightly lower in cases (0.31; 95% CI 0.28-0.34) than in controls (0.33; 0.31-0.35) (difference not significant), whereas geometric mean CB-IgE was significantly higher among cases (0.39; 0.30-0.52) than controls (0.27; 0.23-0.33). No significant differences between cases and controls were found for respiratory rate, peak tidal expiratory flow or expiratory volume. However, the odds ratio for developing recurrent or persistent bronchial obstruction was 3.5 (1.1-11.6) if tPTEF/tE was < 0.20 and 4.1 (1.1-14.5) with maternal daily smoking during the pregnancy, after adjusting for age, weight, sex, CB-IgE, parental atopy, maternal education and family income. The TFV parameter tpTEF/tE < 0.20 measured within the first week of life as well as maternal daily smoking during pregnancy are significant, independent risk factors for developing recurrent or persistent bronchial obstruction within the first two years of life.

Asthma, wheezy bronchitis, and atopy across two generations

Although the prevalence of asthma has risen significantly during the last 30 yr, it is not clear whether this has occurred primarily in persons with a strong genetic predisposition to asthma and atopy or in other sections of the population. We have investigated outcomes in children of nuclear families selected through probands previously characterized by studies in 1964 and 1989 as having histories of persistent childhood onset atopic asthma, transient childhood wheezy bronchitis, and no respiratory symptoms or atopy. Children of wheezy bronchitic probands had a significantly better symptomatic outcome in adolescence, irrespective of the atopic status of the parent proband, than do children of either asthmatic or asymptomatic probands, suggesting that this may be a syndrome that shows familial aggregation and is distinct from asthma. Total serum IgE levels were significantly lower in children of nonatopic asymptomatic probands, including those with wheezing symptoms. In contrast children of nonatopic asymptomatic probands had an unexpectedly high prevalence of wheezing (33%), positive skin prick tests (56%), and positive specific serum IgE to common allergens (48%) that was similar to that found in children of atopic asthmatic probands. Our findings support the concept that wheezy bronchitis is a separate syndrome from atopic asthma. High total serum IgE levels within our population appear to be an important marker of genetic predisposition to atopy. Our data also suggest that much of the increase in asthma prevalence is associated with specific IgE sensitization and is occurring in persons previously considered to be at low risk of developing asthma or atopy.

Increasing risk of asthma without other atopic diseases in school children: a repeated cross-sectional study after 13 years

Some children develop asthma and other atopic diseases, others asthma without atopic diseases. To better understand secular trends, we estimated the relative increase in asthma in children with (atopy related asthma) and without (non-atopy related asthma) other atopic diseases (eczema or hay fever) in two samples of school children born, 1965-1975 (n = 1674) and 1978-1988 (n = 2188). By analysing the samples as historical cohorts, age-specific prevalence rates were estimated and incidence rates were calculated (number of new cases by 1000 person years under risk). Cox regression was used to estimate the relative risk (RR) of asthma by year of birth. The point prevalence of asthma was 1.9% (95% CI: 1.4-2.4) in the 1965-1975 cohort and 4.6% (95% CI: 3.8-5.4) in the 1978-1988 cohort for three-year old children, and remained fairly constant throughout childhood. The age-specific prevalence of non-atopy related asthma increased relatively more from 1965-1975 to 1978-1988 compared to atopy related asthma. The age-specific incidence rates of asthma showed that the RRs comparing the two cohorts tended at all ages to be highest for non-atopy related asthma. The relative risks of non-atopy related asthma by gender and birth cohort, showed that the effect of cohort was higher for non-atopy related asthma, aRR: 4.0 (95 % CI: 2.5-6.5), than for atopy-related asthma aRR: 2.0 (95% CI: 1.3-3.2). Children without other atopic diseases have a higher relative risk of being diagnosed with asthma than children with other atopic diseases across all ages comparing two samples of school children born 1965-1975 and 1978-1988.

Outcome of children of parents with atopic asthma and transient childhood wheezy bronchitis

BACKGROUND

Childhood asthma and wheeze only in the presence of respiratory infection (wheezy bronchitis) appear to have different prognoses and may differ in their aetiology and heritability. In particular, slight reductions in lung function may be associated with episodes of wheezing associated with intercurrent viral infection.

METHODS

Outcomes for wheezing symptoms and lung function were studied in 133 offspring of three distinct groups of 69 middle aged probands with childhood histories of (1) atopic asthma (n = 18), (2) wheeze associated with upper respiratory tract infection (wheezy bronchitis, n = 24), and (3) no symptoms (n = 27). Probands were selected from a previously studied cohort in which outcomes of wheezy bronchitis and asthma had been shown to differ.

RESULTS

Children of probands with wheezy bronchitis had a lower prevalence of current wheezing symptoms. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in boys of probands with a history of wheezy bronchitis were significantly reduced compared with either of the other two groups (p < 0.0001). In a multivariate analysis, grouping based on parent proband had a significant effect on lung function, independent of factors such as symptoms, atopy or smoking history.

CONCLUSIONS

The different symptomatic and lung function outcome in children of probands with wheezy bronchitis and asthma provides further evidence that wheezy bronchitis and asthma differ in their natural history and heritability, and suggests that there may be familial factors specific to each wheezing syndrome.