Episodes of respiratory morbidity in children with cough and wheeze

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.

Monitoring asthma in childhood: lung function, bronchial responsiveness and inflammation

This review focuses on the methods available for measuring reversible airways obstruction, bronchial hyperresponsiveness (BHR) and inflammation as hallmarks of asthma, and their role in monitoring children with asthma. Persistent bronchial obstruction may occur in asymptomatic children and is considered a risk factor for severe asthma episodes and is associated with poor asthma outcome. Annual measurement of forced expiratory volume in 1 s using office based spirometry is considered useful. Other lung function measurements including the assessment of BHR may be reserved for children with possible exercise limitations, poor symptom perception and those not responding to their current treatment or with atypical asthma symptoms, and performed on a higher specialty level. To date, for most methods of measuring lung function there are no proper randomised controlled or large longitudinal studies available to establish their role in asthma management in children. Noninvasive biomarkers for monitoring inflammation in children are available, for example the measurement of exhaled nitric oxide fraction, and the assessment of induced sputum cytology or inflammatory mediators in the exhaled breath condensate. However, their role and usefulness in routine clinical practice to monitor and guide therapy remains unclear, and therefore, their use should be reserved for selected cases.

Airway obstruction at time of symptoms prompting use of reliever therapy in children with asthma

BACKGROUND

In asthma treatment, doses of inhaled corticosteroids are often adapted to symptoms and need for bronchodilators. However, in cross-sectional studies in emergency room settings, lung function and respiratory symptoms are not always concordant. Available longitudinal data are based on written peak flow diaries, which are unreliable. Using home spirometry, we studied prospectively whether mild respiratory symptoms, prompting reliever therapy are accompanied by a clinically relevant drop in lung function in children with asthma.

METHODS

For 8 weeks, children with asthma scored symptoms and measured peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) on a home spirometer twice daily. Additional measurements were recorded when respiratory symptoms prompted them to use bronchodilators.

RESULTS

The mean difference between symptom free days and at times of symptoms was 6.6% of personal best for PEF (95% CI: 3.2-10.0; p = 0.0004) and 6.0% of predicted for FEV(1) (95% CI: 3.0-9.0; p = 0.0004). There was complete overlap in PEF and FEV(1) distributions between symptom free days and at times of symptoms.

CONCLUSIONS

Although statistically significant, the degree of airway narrowing at times of respiratory symptoms, prompting the use of reliever therapy, is highly variable between patients, limiting the usefulness of home spirometry to monitor childhood asthma.

Anti-histamines for prolonged non-specific cough in children

BACKGROUND

Non-specific cough is defined as non-productive cough in the absence of identifiable respiratory disease or known aetiology. It is commonly seen in paediatric practice. These children are treated with a variety of therapies including anti-histamines. Also, anti-histamines are advocated as an empirical treatment in adults with chronic cough.

OBJECTIVES

To evaluate the effectiveness of anti-histamines in treating children with prolonged non-specific cough.

SEARCH STRATEGY

We searched the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, OLDMEDLINE and EMBASE databases. The latest searches were performed in November 2007.

SELECTION CRITERIA

All randomised controlled trials comparing anti-histamines with a placebo or placebo-like medication with cough as an outcome, where cough is not primarily related to an underlying respiratory disorder such as cystic fibrosis, asthma, or suppurative lung disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and extracted data.

MAIN RESULTS

Three included therapeutic studies had 182 randomised participants with 162 completing the trials although in one study, children with recurrent wheeze were also included. The two included safety evaluation studies randomised 963 participants with 793 completing the trials. Clinical heterogeneity was evident and limited data prevented combining data for meta-analysis. The two larger therapeutic studies described significant improvement in both the intervention and the placebo/placebo-like arms with no significant difference between the two groups. In the study with the smallest sample size, cetirizine (a second generation anti-histamine) was significantly more efficacious than placebo in reducing chronic cough in children associated with seasonal allergic rhinitis, and the effect was seen within two weeks of therapy. Combined data from the safety evaluation studies revealed a non-significant difference between groups (OR 1.6, 95% CI 0.7 to 3.82) for cough as an adverse event but the trend favoured the placebo arm.

AUTHORS' CONCLUSIONS

This review has significant limitations. However, our finding of uncertain efficacy of anti-histamines for chronic cough are similar to that for acute cough in children. In contrast to recommendations in adults with chronic cough, anti-histamines cannot be recommended as empirical therapy for children with chronic cough. If anti-histamines were to be trialled in these children, current data suggest a clinical response (time to response) occurs within two weeks of therapy. However the use of anti-histamines in children with non-specific cough has to be balanced against the well known risk of adverse events especially in very young children.

Asthma

Asthma has been recognized as a disease since the earliest times. In the Corpus Hippocraticum, Hippocrates used the term “ασθμα” to indicate any form of breathing difficulty manifesting itself by panting. Aretaeus of Cappadocia, a well-known Greek physician (second century A.D.), is credited with providing the first detailed description of an asthma attack [13], and to Celsus it was a disease with wheezing and noisy, violent breathing. In the history of Rome, we find many members of the Julio-Claudian family affected with probable atopic respiratory disorders: Caesar Augustus suffered from bronchoconstriction, seasonal rhinitis as well as a highly pruritic skin disease. Claudius suffered from rhinoconjunctivitis and Britannicus was allergic to horse dander [529]. Maimonides (1136–1204) warned that to neglect treatment of asthma could prove fatal, whereas until the 19th century, European scholars defined it as “nervous asthma,” a term that was given to mean a defect of conductivity of the ninth pair of cranial nerves.

Relationship among pulmonary function, bronchial hyperresponsiveness, and atopy in children with clinically stable asthma

Pulmonary function testing plays a key role in the diagnosis and management of asthma in children. However, the literature does not clearly show whether children with clinically stable asthma have significantly reduced lung function when compared with normal children. We compared the lung function of 242 clinically stable asthmatic children who were initially diagnosed with mild intermittent or mild persistent asthma with the lung function of 100 nonasthmatic controls. The lung function was assessed using FEV1, FEV1/FVC, FEF25-75 and PEF. In addition, we measured bronchial hyperresponsiveness (BHR) using the provocation concentration of methacholine needed to produce a 20% fall in FEV1. All measures of pulmonary function were significantly decreased in the children with asthma. Pulmonary function was not influenced by atopy, serum IgE, or total eosinophil count (TEC). However, the likelihood ratio for trends revealed a significant association between our pulmonary parameters and the degree of BHR. Children with mild-to-severe BHR had greatly decreased lung function compared with those with normal BHR, the control group. In addition, a direct correlation was found between PC20 and our pulmonary parameters in asthmatic children. However, only atopic children with asthma had a significant correlation between PC20 and TEC. We found children with clinically stable asthma to have pulmonary obstruction, which associated strongly with their degree of BHR.

Anti-histamines for prolonged non-specific cough in children

BACKGROUND

Non-specific cough is defined as non-productive cough in the absence of identifiable respiratory disease or known aetiology. It is commonly seen in paediatric practice. These children are treated with a variety of therapies including anti-histamines. Also, anti-histamines are advocated as an empirical treatment in adults with chronic cough.

OBJECTIVES

To evaluate the effectiveness of anti-histamines in treating children with prolonged non-specific cough.

SEARCH STRATEGY

The Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, OLDMEDLINE and EMBASE databases were searched by the Cochrane Airways Group. The latest searches were performed in November 2005.

SELECTION CRITERIA

All randomised controlled trials comparing anti-histamines with a placebo or placebo-like medication with cough as an outcome, where cough is not primarily related to an underlying respiratory disorder such as cystic fibrosis, asthma, or suppurative lung disease.

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against pre-determined criteria for inclusion. Two independent reviewers selected, extracted and assessed data for inclusion. Three eligible trials were identified.

MAIN RESULTS

The three included studies varied in age of subjects, sample size, inclusion criteria, type of anti-histamine and length of intervention. These 3 studies included 182 randomised subjects with 162 completing the trials although in one study, children with recurrent wheeze were also included. Clinical heterogeneity was evident and limited data prevented combining data for meta-analysis. The two larger studies described significant improvement in both the intervention and the placebo/placebo-like arms with no significant difference between the two groups. In the study with the smallest sample size, cetirizine (a second generation anti-histamine) was significantly more efficacious than placebo in reducing chronic cough in children associated with seasonal allergic rhinitis, and the effect was seen within 2 weeks of therapy.

AUTHORS' CONCLUSIONS

This review has significant limitations. However, our finding of uncertain efficacy of anti-histamines for chronic cough are similar to that for acute cough in children. In contrast to recommendations in adults with chronic cough, anti-histamines cannot be recommended as empirical therapy for children with chronic cough. If anti-histamines were to be trialled in these children, current data suggest a clinical response (time to response) occurs within 2 weeks of therapy. However the use of anti-histamines in children with non-specific cough has to be balanced against the well known risk of adverse events especially in very young children.

Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines

OBJECTIVES

To review relevant literature and present evidence-based guidelines to assist general and specialist medical practitioners in the evaluation and management of children who present with chronic cough.

METHODOLOGY

The Cochrane, MEDLINE, and EMBASE databases, review articles, and reference lists of relevant articles were searched and reviewed by a single author. The date of the last comprehensive search was December 5, 2003, and that of the Cochrane database was November 7, 2004. The authors' own databases and expertise identified additional articles.

RESULTS/CONCLUSIONS

Pediatric chronic cough (ie, cough in children aged <15 years) is defined as a daily cough lasting for >4 weeks. This time frame was chosen based on the natural history of URTIs in children and differs from the definition of chronic cough in adults. In this guideline, only chronic cough will be discussed. Chronic cough is subdivided into specific cough (ie, cough associated with other symptoms and signs suggestive of an associated or underlying problem) and nonspecific cough (ie, dry cough in the absence of an identifiable respiratory disease of known etiology). The majority of this section focuses on nonspecific cough, as specific cough encompasses the entire spectrum of pediatric pulmonology. A review of the literature revealed few randomized controlled trials for treatment of nonspecific cough. Management guidelines are summarized in two pathways. Recommendations are derived from a systematic review of the literature and were integrated with expert opinion. They are a general guideline only, do not substitute for sound clinical judgment, and are not intended to be used as a protocol for the management of all children with a coughing illness. Children (aged <15 years) with cough should be managed according to child-specific guidelines, which differ from those for adults as the etiologic factors and treatments for children are sometimes different from those for adults. Cough in children should be treated based on etiology, and there is no evidence for using medications for the symptomatic relief of cough. If medications are used, it is imperative that the children are followed up and therapy with the medications stopped if there is no effect on the cough within an expected time frame. An evaluation of the time to response is important. Irrespective of diagnosis, environmental influences and parental expectations should be discussed and managed accordingly. Cough often impacts the quality of life of both children and parents, and the exploration of parental expectations and fears is often valuable in the management of cough in children.

Inhaled corticosteroids for non-specific chronic cough in children

BACKGROUND

Cough in isolation of other clinical features is known as non-specific cough, which has been defined as non-productive cough in the absence of identifiable respiratory disease or any known aetiology. In children with non-specific cough the possibility of asthma being the underlying disorder is often raised (so called cough variant asthma). The proponents of cough variant asthma suggest a therapeutic trial of medications usually used to treat asthma.

OBJECTIVES

To determine the efficacy of inhaled corticosteroids in non-specific cough in children over the age of two years.

SEARCH STRATEGY

Searches were conducted on Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Searches were current as of March 2004.

SELECTION CRITERIA

All randomised (randomised and quasi-randomised) controlled clinical trials in which an inhaled corticosteroid (beclomethasone (BDP), fluticasone (FP), triamcinalone (TAA) or any other corticosteroid) were given for cough in children over two years of age were included. Two review authors independently assessed articles for inclusion and methodological quality.

DATA COLLECTION AND ANALYSIS

Data from trials was extracted by both review authors and entered into the Cochrane Collaboration software program RevMan Analyses 1.0.2.

MAIN RESULTS

Two trials met the inclusion criteria (123 participants). One compared inhaled beclomethasone dipropionate (400 micrograms per day) with placebo and the other compared fluticasone propionate (2 mg per day for 3 days followed by 1 mg per day for 11 days) with placebo. Both studies used metered dose inhalers via a spacer. With the lower dose of inhaled corticosteroid there was no significant difference between the beclomethasone and placebo groups. With the higher dose there was a significant improvement in nocturnal cough frequency after two weeks in children presenting with persistent nocturnal cough. However, a significant but smaller improvement was also seen with placebo.

AUTHORS' CONCLUSIONS

In one study beclomethasone dipropionate (400 micrograms per day) was no different from placebo in reducing the frequency of cough measured objectively or scored subjectively. There might be a small improvement with very high-dose inhaled corticosteroid but the clinical impact of this is unlikely to beneficial.

Cough: are children really different to adults?

Worldwide paediatricians advocate that children should be managed differently from adults. In this article, similarities and differences between children and adults related to cough are presented. Physiologically, the cough pathway is closely linked to the control of breathing (the central respiratory pattern generator). As respiratory control and associated reflexes undergo a maturation process, it is expected that the cough would likewise undergo developmental stages as well. Clinically, the 'big three' causes of chronic cough in adults (asthma, post-nasal drip and gastroesophageal reflux) are far less common causes of chronic cough in children. This has been repeatedly shown by different groups in both clinical and epidemiological studies. Therapeutically, some medications used empirically for cough in adults have little role in paediatrics. For example, anti-histamines (in particular H1 antagonists) recommended as a front-line empirical treatment of chronic cough in adults have no effect in paediatric cough. Instead it is associated with adverse reactions and toxicity. Similarly, codeine and its derivatives used widely for cough in adults are not efficacious in children and are contraindicated in young children. Corticosteroids, the other front-line empirical therapy recommended for adults, are also minimally (if at all) efficacious for treating non-specific cough in children. In summary, current data support that management guidelines for paediatric cough should be different to those in adults as the aetiological factors and treatment in children significantly differ to those in adults.

[Acute viral respiratory tract infections and childhood asthma]

Les infections virales respiratoires sont de très importants facteurs déclenchants des crises d'asthme. Chez l'enfant les études épidémiologiques les plus récentes, utilisant la PCR, leur attribuent le déclenchement de 80 à 85 % des crises, aussi bien pour les crises modérées que les crises nécessitant une hospitalisation. Le virus respiratoire syncytial et les virus parainfluenzae prédominent chez le nourrisson, les rhinovirus et le mycoplasme chez l'enfant plus grand. Les mécanismes précis de l'induction des crises d'asthme par les virus restent mal compris, toutefois de récentes études montrent une augmentation de l'activation des cellules inflammatoires dans le lavage alvéolaire. Les sujets atopiques, en dehors des périodes d'allergie, ne semblent pas avoir plus de manifestations respiratoires viro-induites que les non-atopiques. En revanche, chez le sujet asthmatique, l'infection virale aggrave les réactions immédiate et retardée de l'hypersensibilité immédiate après test de provocation allergénique, en augmentant la libération des médiateurs mastocytaires et le recrutement des éosinophiles dans les voies aériennes inférieures. Les études chez l'homme et l'animal suggèrent que la production locale de cytokines (IL4, IL8, RANTES, MIP-1a...) et l'expression accrue chez l'asthmatique de la molécule d'adhésion ICAM1 aient un rôle important pour le recrutement et l'activation des cellules de l'inflammation dans les voies aériennes. Une hypothèse, qui reste à démontrer serait que dans des situations où, comme dans l'asthme, les lymphocytes Th2 prédominent, un excès d'Il4 pourrait inhiber les CD8 cytotoxiques, les cellules NK et les Th1 et ainsi entraîner une diminution des défenses antivirales et une réaction inflammatoire broncho-pulmonaire plus sévère que chez le non-asthmatique.

[Epidemiology of viral infection and asthma]

The first epidemiological data concerning viruses and asthma were obtained in the 1970s and 1980s by viral isolation and serology. Viral infection can be identified in 24 % to 31.9 % of children, and in 13.3 % of adults. The three most frequent viruses are rhinovirus (RV), respiratory syncytial virus (RSV), and parainfluenza viruses (PIV), detected in 8.8 %, 6.4 % and 6 % of cases, respectively. Due to its amplifying properties, the use of PCR increases the frequency of viral detection, and appears particularly appropriate in asthma where the viral load can be reduced. In a study of bronchiolitis, RSV, PIV3, AdV and RV were identified in 39.3 %, 4.3 %, 1.4 % and 3.9 % of cases, respectively, by IF or culture, and in 62.4 %, 8.3 %, 10.8 % and 12.6 % of cases, respectively, by PCR. Two recent epidemiological surveys used molecular diagnosis in asthma attacks. In a series of 61 adults, 27 (44 %) infections were identified: 16 RV, 4 CV OC43, 3 PIV, 1 RSV, 1 VI, 1 Chlamydia psitacci. In children, viral infection was detected in 226 cases (77 %) : 84 RV, 38 CV, 21 IV, 21 PIV, 12 RSV. We have performed a short retrospective survey for 1997, using molecular biology, on 39 nasal aspirates from children consulting for asthma or wheezing bronchitis. Testing for respiratory viruses by conventional techniques identified 8 (20.5 %) viral infections: 3 RV, 3 RSV, 1 IBV and 1 VPI2. After nucleic acid extraction, PCR-hybridization techniques were applied to these samples to detect RSV, AdV, RV, CV 229E, CV OC43, CP and MP sequences. Twenty six aspirates (54 %) were positive only on molecular biology techniques: 11 RSV, 12 RV, 2 enterovirus, 1 CV OC43. Overall 34 (82 %) viral infections were detected in these children, and a mixed RSV-RV infection was identified in 6 cases. Compared to the studies reported in the literature, we observed the same predominance of RV infections, more RSV infections, probably related to the use of PCR, and a lower incidence of CV infections.

Cough, wheezing and asthma in children: lesson from the past

Recurrent cough is an important medical and sometimes frustrating problem encountered by pediatricians, especially if it is not associated with wheeze or other evidence of systemic disease. In the past, many children with chronic cough have been diagnosed as asthmatic. However, epidemiological, clinical and laboratory studies conducted over the last ten years elucidated many aspects of the relationship between cough and bronchoconstriction. It is difficult to make a diagnosis of asthma on cough alone, but the setting in which the patient is seen (i.e., in a primary care setting or ain a specialistic clinic) may address doctors to the right diagnosis. A prudent ''wait and see'' approach may be useful in many occasions.

Mild persistent asthma. Traits, treatment set it apart from mild intermittent asthma

Mild persistent asthma has greater airway hyperresponsiveness than mild intermittent asthma and may also have more persistent respiratory symptoms and more severe consequences. By other measures, the two conditions are not always easy to differentiate. Nevertheless, primary care physicians need to be able to recognize and treat mild persistent asthma in order to reduce the number of severe exacerbations, and even fatalities, that can occur if it is not properly managed. In this article, Dr Lim discusses how to differentiate mild persistent asthma from mild intermittent asthma and explores the best options for pharmacologic treatment.

Symptoms of asthma: comparison of a parent-completed retrospective questionnaire with a prospective daily symptom diary

In a study of the effects of indoor air pollution on the respiratory health of children in Newcastle, Australia, parental reports of symptoms experienced by children over the previous 12 months were compared with a prospective record of symptoms of cough and wheeze. Parents of 390 children aged 8-11 years completed a questionnaire about child and family respiratory health, which was used to assign children to one of four symptom groups: Wheeze (two or more attacks of wheezing in the last 12 months), Chest-Colds (two or more chest-colds in the last 12 months without wheezing), Cough Alone (a dry cough at night, without a cold or chest infection, that lasted for more than 2 weeks), or Control (none). A balanced sample of children (n=139) was invited to participate further by completing lung function tests, atopy testing, and keeping a daily diary of peak expiratory flow (PEF) and symptoms of cough and wheeze over a 7-week period. Valid data for the daily diary were provided by 66/85 (77.6%) of participants who commenced this stage (47.5% of the 139 invited to participate). The Wheeze group reported significantly more subsequent wheeze (median 16.8% of days) than the other three groups (median 0% of days). Parent reports of asthma-like symptoms over the previous 12 months were consistent with the subsequent experience of symptoms recorded in a daily diary.

Usefulness of monitoring lung function in asthma

There is no firm evidence from randomised controlled trials that routine monitoring of lung function improves asthma control in children. Guidelines for management of asthma consistently recommend routine home monitoring of peak expiratory flow (PEF) in each patient. However, changes in PEF poorly reflect changes in asthma activity, PEF diaries are kept very unreliably, and self management programmes including PEF monitoring are no more effective than programmes solely based on education and symptom monitoring. PEF diaries may still be useful in isolated cases of diagnostic uncertainty, in the identification of exacerbating factors, and in the rare case of children perceiving airways obstruction poorly and exacerbating frequently and severely. If a reliable assessment of airways obstruction in asthma is needed, forced expiratory flow-volume curves are the preferred method. Monitoring of hyperresponsiveness and nitric oxide cannot be recommended for routine use at present. Clinical judgement and expiratory flow-volume loops remain the cornerstone of monitoring asthma in secondary care.

[Viral identification, and during asthma exacerbation: comparative epidemiology between infants and children.]

Objectifs. – L’utilisation des nouvelles techniques d’identification par les méthodes moléculaires apporte de nouvelles données épidémiologiques.

Patients et méthodes. – Cent dix-huit aspirations nasales pratiquées chez des enfants hospitalisés pour une exacerbation aiguë d’asthme ont été colligées. Les techniques conventionnelles ont associé la culture virale et l’immunofluorescence et les techniques moléculaires une polymerase chain reaction (PCR).

Résultats. – L’utilisation des techniques conventionnelles a mis en évidence un virus dans 34 % des prélèvements respiratoires (40 cas sur 118), tandis que l’étude par PCR permet une identification positive sur 68 % des prélèvements (80 cas sur 118) et l’association des deux méthodes amène la positivité à 77 % (91 cas sur 118). Les co-infections ont concerné 23 % des prélèvements positifs. L’identification virale par les outils traditionnels est significativement plus fréquente chez les jeunes asthmatiques, ainsi que lors de l’utilisation des outils de biologie moléculaire de façon non significative. L’épidémiologie comparative retrouve la prépondérance dans les deux groupes d’âge du rhinovirus (45 %), puis du virus respiratoire syncytial (28 %) et de l’entérovirus (8,5 %). Chez les enfants âgés de moins de deux ans, rhinovirus et virus respiratoire syncytial ont une prévalence proche (42 et 36 % respectivement) sensiblement différente de celle des enfants âgés de plus de deux ans (66 et 27 % respectivement). L’identification par PCR de Chlamydia pneumoniae et de Mycoplasma pneumoniae reste rare (six cas sur 118 prélèvements).

Conclusion. – La prééminence du rhinovirus et du virus respiratoire syncytial est retrouvée lors des exacerbations d’asthme chez le nourrisson tandis que C. pneumoniae et M. pneumoniae ne semblent pas particulièrement impliqués. L’identification est plus forte chez les jeunes asthmatiques avec probablement une charge virale plus importante, car la positivité de la culture virale est plus fréquente chez les enfants âgés de moins de deux ans.

Airway eosinophilia is associated with wheeze but is uncommon in children with persistent cough and frequent chest colds

The role of eosinophilic airway inflammation in the variant asthma syndromes of cough and chest colds is not well defined. We tested the hypothesis that children with persistent cough and chest colds have increased sputum eosinophils, similar to those with wheeze. The parents of 390 primary school children completed a symptoms questionnaire. Children with wheeze (n = 28), cough (n = 12), recurrent chest colds (n = 17), and no symptoms (control subjects, n = 26), underwent allergy skin prick tests, spirometry, hypertonic saline inhalation challenge, and sputum induction, and then completed a peak expiratory flow (PEF) and symptoms diary over a 2-mo period. Children with wheeze had significantly reduced PEF (p = 0.001) and higher sputum eosinophils when compared with the cough, chest cold, and control groups (3.1% versus 0.5%, 0%, 0%; p = 0.03). The prevalence of eosinophilic bronchitis (sputum eosinophils > 2.5%) was 45% in the wheeze group, which was significantly higher than the control group (9.35%, p = 0.04). Eosinophilic bronchitis was present in two children with cough (20%) and two with chest colds (15%, p > 0.05 versus control). In these groups, eosinophilic bronchitis was not associated with airway hyperresponsiveness (AHR) to hypertonic saline (p > 0.05). Children with cough and chest colds reported greater exposure to environmental tobacco smoke. In conclusion, this community-based survey of children with chronic respiratory symptoms has shown that wheeze is a good discriminator for the presence of eosinophilic bronchitis, and that persistent cough and recurrent chest colds without wheeze should not be considered a variant of asthma. Eosinophilic bronchitis did occur in a significant minority of these "variant asthma" syndromes.

A review of cough in children

Cough is a very common symptom of respiratory disease and reason for parents to seek medical attention. The article presents broad clinical guidelines on the approach to childhood cough and discusses current controversies of the management of cough in children.

The role of acute and chronic stress in asthma attacks in children

BACKGROUND

High levels of stress have been shown to predict the onset of asthma in children genetically at risk, and to correlate with higher asthma morbidity. Our study set out to examine whether stressful experiences actually provoke new exacerbations in children who already have asthma.

METHODS

A group of child patients with verified chronic asthma were prospectively followed up for 18 months. We used continuous monitoring of asthma by the use of diaries and daily peak-flow values, accompanied by repeated interview assessments of life events and long-term psychosocial experiences. The key measures included asthma exacerbations, severely negative life events, and chronic stressors.

FINDINGS

Severe events, both on their own and in conjunction with high chronic stress, significantly increased the risk of new asthma attacks. The effect of severe events without accompanying chronic stress involved a small delay; they had no effect within the first 2 weeks, but significantly increased the risk in the subsequent 4 weeks (odds ratio 1.71 [95% CI 1.04-2.82], p < or = 0.05 for weeks 2-4 and 2.17 [1.32-3.57], p < or = 0.01 for weeks 4-6). When severe events occurred against the backdrop of high chronic stress, the risk increased sharply and almost immediately within the first fortnight (2.98 [1.20-7.38], p < or = 0.05). The overall attack frequency was affected by several factors, some related to asthma and some to child characteristics. Female sex, higher baseline illness severity, three or more attacks within 6 months, autumn to winter season, and parental smoking were all related to increased risk of new exacerbations; social class and chronic stress were not.

INTERPRETATION

Severely negative life events increase the risk of children's asthma attacks over the coming few weeks. This risk is magnified and brought forward in time if the child's life situation is also characterised by multiple chronic stressors.

Induced sputum: comparison of postinfectious cough with allergic asthma in children

BACKGROUND

Cough persisting after a respiratory infection is common in children and is often managed as asthma. However, little is known about the pathophysiologic mechanisms of such cough and how it compares with asthma.

OBJECTIVE

We used the technique of induced sputum to examine the inflammatory index values associated with persistent cough or allergic asthma in children. We hypothesized that the sputum from children with persistent postinfectious cough would differ from that of children with allergic asthma in that the former would lack eosinophils compared with the latter.

STUDY DESIGN

Sputum production was induced with hypertonic saline solution in 34 children: 12 with cough persisting for 1 month or more after an apparent respiratory tract infection, not treated with corticosteroid; 11 with untreated atopic asthma, not using inhaled corticosteroid; and 11 with treated atopic asthma using inhaled corticosteroid.

RESULTS

The percentage of eosinophils in the sputum of children with cough was significantly lower than in the sputum of children with untreated allergic asthma (median 0.5% vs 14.5%, P <.0001). Similarly, the percentage of eosinophils in the sputum of children with asthma treated with inhaled steroids was significantly lower compared with untreated asthmatic children (1.5% vs 14.5%, P <.0001). The peripheral blood eosinophils, serum eosinophil cationic protein, and nasal percent eosinophils of the patients with cough were also significantly lower than those from patients with untreated asthma. Methacholine challenge in 6 of the 11 cough patients tested showed mild-to-moderate hyperresponsiveness, whereas the other 5 had a negative methacholine challenge.

CONCLUSIONS

Children with persistent postinfectious cough do not have airway eosinophilia typical of untreated asthma. Despite the absence of eosinophilic inflammation, some of the patients with chronic cough had reactive airways. These results suggest that postinfectious cough in children has different pathophysiologic features than allergic asthma and probably represents a different disease.

Persistent nocturnal cough: randomised controlled trial of high dose inhaled corticosteroid

OBJECTIVE

To investigate the effect of a short course of inhaled corticosteroid in the treatment of isolated and persistent nocturnal cough in children.

DESIGN

Randomised double blind placebo controlled study.

SETTING

Subjects' homes in east London, England.

SUBJECTS

Consecutively referred children, 1-10 years old, with persistent nocturnal cough.

INTERVENTIONS

Placebo or fluticasone propionate 1 mg twice daily for three nights and 500 microg twice daily for 11 nights. Videotaping of children at night: two nights' baseline, nights 3 and 4 after three days of inhaled corticosteroid, and nights 15 and 16.

MAIN OUTCOME MEASURE

A fall in 75% of coughs from baseline.

RESULTS

50 subjects were recruited. The median number of coughs in the baseline period for the inhaled corticosteroid group and placebo group were 92 and 71, respectively (p = 0.43) and, on nights 15 and 16, 8 and 36, respectively (p < 0. 01). Compared to baseline, both groups of subjects improved significantly by nights 15 and 16 (p < 0.01; p < 0.01). Comparing the inhaled corticosteroid and placebo groups, coughs fell to a median of 22% and 57% of baseline totals on nights 3 and 4, respectively (p = 0.38), and 8% and 35% on nights 15 and 16, respectively (p = 0.02). 17 of 24 subjects on inhaled corticosteroid who completed the study and 8 of 23 on placebo improved by 75% after two weeks (p = 0.03).

CONCLUSIONS

Children with persistent nocturnal cough improve in two weeks after referral on placebo. There is a modest benefit from a two week course of high dose inhaled corticosteroid.

Peak flow variation in childhood asthma: correlation with symptoms, airways obstruction, and hyperresponsiveness during long-term treatment with inhaled corticosteroids. Dutch CNSLD Study Group

BACKGROUND

Guidelines for asthma management focus on treatment with inhaled corticosteroids and on home recording of peak expiratory flow (PEF). The effect of maintenance treatment with inhaled corticosteroids on PEF variation and its relation to other parameters of disease activity were examined in 102 asthmatic children aged 7-14 years.

METHODS

During 20 months of treatment with inhaled salbutamol, with or without inhaled budesonide (600 micrograms daily), forced expiratory volume in one second (FEV1), the dose of histamine required to provoke a fall in FEV1 of more than 20% (PD20), the percentage of symptom free days, and PEF variation were assessed bimonthly. PEF variation was computed as the lowest PEF as a percentage of the highest PEF occurring over 14 days, the usual way of expressing PEF variation in asthma self-management plans. For each patient using inhaled corticosteroids within subject correlation coefficients (rho) were computed of PEF variation to the percentage of symptom free days, FEV1, and PD20.

RESULTS

PEF variation decreased significantly during the first two months of treatment with inhaled corticosteroids and then remained stable. The same pattern was observed for symptoms and FEV1. In contrast, PD20 histamine continued to improve throughout the whole follow up period. In individual patients predominantly positive associations of PEF variation with symptoms, FEV1, and PD20 were found, but the ranges of these associations were wide.

CONCLUSIONS

During treatment with inhaled corticosteroids the changes in PEF variation over time show poor concordance with changes in other parameters of asthma severity. When only PEF is monitored, clinically relevant deteriorations in symptoms, FEV1, or PD20 may be missed. This suggests that home recording of PEF alone may not be sufficient to monitor asthma severity reliably in children.

Measuring persistent cough in children in epidemiological studies: development of a questionnaire and assessment of prevalence in two countries

STUDY OBJECTIVE

Cough is a common symptom in children that is frequently encountered in general practice. However, most of the information on the prevalence of persistent cough has come from studies that use different, often ambiguous, definitions for persistent cough. It is therefore important that a validated questionnaire to accurately measure persistent cough is developed and is appropriate for use in different age groups of children and in different cultures. Such a questionnaire is essential for accurately measuring the prevalence of persistent cough and the factors associated with its occurrence.

DESIGN

A parent-administered respiratory questionnaire was developed and administered twice during a 3-week interval pilot study to test repeatability. The questionnaire was then administered to a randomly selected cross-section of Australian children aged 5 to 7 years old and 8 to 11 years old (N = 511 and N = 654, respectively), and to 566 Nigerian children aged 8 to 11 years old.

RESULTS

The new questionnaire was reliable, with most of the questions having a kappa value of above 0.6. The prevalence of persistent cough was similar in younger and older Australian children, but significantly less in Nigerian children (p < 0.001). Also, persistent cough was more prevalent in children of high rather than low socioeconomic status among older Australian children (p = 0.04).

CONCLUSIONS

The newly developed questionnaire will be an important tool in epidemiological studies for measuring the prevalence, morbidity, and risk factors of persistent cough in childhood. Although our findings showed that persistent cough does not occur more frequently in younger than in older Australian children, it is more frequent in Australian than in Nigerian children.

[Respiratory allergy and the viruses]

Viral respiratory tract infections are a major cause of wheezing in infants. Investigators determined that 80% to 85% of school-aged children with wheezing episodes were tested positive for virus. To more fully understand how viral respiratory tract infections influence asthma, investigators have evaluated the effect of respiratory tract infections on airway symptoms, function, and inflammation. Although the mechanisms by which respiratory viruses enhance lower airway inflammation are not established, cytokines may play a key role in this process. The respiratory epithelial cell is a principal host for respiratory virus replication and is likely to be the first source of cytokines during an acute infection. T cells orchestrate immune responses to both allergens and viruses, and regulate effector cells with virucidal and proinflammatory effects. Although studies demonstrate that virus-specific T cells may contribute to virus-induced lung disease, evidence to define the role of virus-specific T lymphocytes in asthma has not been fully established. Some infections early in life may also have an important immunoregulary role in the subsequent development of allergy and asthma. Atopy is characterised by exaggerated Th-2 cell responses to common allergens with secretion of cytokines such as IL-4 and IL-5 that promote IgE production and eosinophil activation. In contrast, childhood infections typically induce a Th-1 cell response, characterised by secretion of interferon-gamma, which enhances the antiviral activities of effector cells. These two types of T cell responses are mutually antagonistic.

The natural history of respiratory symptoms in a cohort of adolescents

A cohort of 2,289 children, previously studied at the age of 6-8 yr, were followed up by means of a postal questionnaire when aged 14 -16 yr to examine the association between potential risk factors and the natural history of respiratory symptoms. Children with current symptoms, persistent symptoms, and late-onset symptoms were identified and multivariate analyses were performed to determine the independent association between risk factors and these various symptom-based subgroups. Personal and family history of atopy was significantly associated with all symptom groups and with the presence of doctor-diagnosed asthma. Smoking, either active or passive, was shown to be significantly associated with current, persistent, and late-onset symptoms. Other factors shown to be significantly associated with certain symptom groups were gender (late-onset wheeze), single-parent households (current cough, persistent cough), social class (late-onset wheeze), number of children in the household (persistent wheeze, late-onset cough), number of furry pets in the household (current wheeze), birth weight (late-onset wheeze), and gas cookers (current wheeze, persistent wheeze). In a subgroup of children studied in more detail in 1987, bronchial hyperresponsiveness in 1987 was positively associated with persistent wheeze in 1995, whereas positive skin-prick testing in 1987 was not.

Community study of role of viral infections in exacerbations of asthma in 9-11 year old children

OBJECTIVE

To study the association between upper and lower respiratory viral infections and acute exacerbations of asthma in schoolchildren in the community.

DESIGN

Community based 13 month longitudinal study using diary card respiratory symptom and peak expiratory flow monitoring to allow early sampling for viruses.

SUBJECTS

108 Children aged 9-11 years who had reported wheeze or cough, or both, in a questionnaire.

SETTING

Southampton and surrounding community.

MAIN OUTCOME MEASURES

Upper and lower respiratory viral infections detected by polymerase chain reaction or conventional methods, reported exacerbations of asthma, computer identified episodes of respiratory tract symptoms or peak flow reductions.

RESULTS

Viruses were detected in 80% of reported episodes of reduced peak expiratory flow, 80% of reported episodes of wheeze, and in 85% of reported episodes of upper respiratory symptoms, cough, wheeze, and a fall in peak expiratory flow. The median duration of reported falls in peak expiratory flow was 14 days, and the median maximum fall in peak expiratory flow was 81 l/min. The most commonly identified virus type was rhinovirus.

CONCLUSIONS

This study supports the hypothesis that upper respiratory viral infections are associated with 80-85% of asthma exacerbations in school age children.