Natural history of allergy in asthmatic children followed to adult life

Transition for Adolescents and Young Adults With Asthma

Asthma is a complex, heterogenous medical condition which is very common in children and adults. The transition process from pediatric to adult health care services can be a challenge for young people with chronic medical conditions. The significant changes in physical and mental health during this time, as well as the many unique developmental and psychosocial challenges that occur during adolescence can complicate and impede transition if not adequately addressed and managed. The transition period can also be a challenging time for health professionals to assess readiness for transition and manage some of the complications which are particularly common during this time, including poor adherence to therapy, smoking, drug use, and emerging mental health conditions. The natural history, presentation, symptoms, and management of asthma is often significantly different when comparing pediatric and adult practice. In addition, management in infants, toddlers, school aged children, and adolescents differs significantly, offering an additional challenge to pediatric physicians managing asthmatic children and young people. Despite these challenges, if the transition process for young people with asthma is planned and performed in a formalized manner, many of these issues can be addressed, allowing the transition to occur smoothly despite changes that may occur in medical and psychosocial domains.

Breastfeeding duration and asthma in Puerto Rican children

RATIONALE

Little is known about breastfeeding and asthma in Puerto Ricans, the ethnic group most affected by this disease in the US. We examined the relation between the currently recommended duration of breastfeeding and asthma in school-aged Puerto Rican children.

METHODS

Case-control study of 1,127 Puerto Rican children aged 6-14 years living in Hartford, Connecticut (n = 449) and San Juan, Puerto Rico (n = 678). Parental recall of breastfeeding was categorized based on duration and according to current guidelines (i.e., none, 0-6 months, and >6 months). Asthma was defined as parental report of physician-diagnosed asthma and wheeze in the previous year. We used logistic regression for the multivariate analysis, which was conducted separately for each study site and for the combined cohort. All multivariate models were adjusted for age, gender, household income, atopy, maternal asthma, body mass index, early-life exposure to environmental tobacco smoke, and (for the combined cohort) study site.

RESULTS

After adjustment for covariates, children who were breastfed for up to 6 months had 30% lower odds of asthma (95% CI = 0.5-1.0, P = 0.04) than those who were not breastfed. In this analysis, breastfeeding for longer than 6 months was not significantly associated with asthma (OR = 1.5, 95% CI = 1.0-2.4, P = 0.06).

CONCLUSIONS

Our results suggest that breastfeeding for up to 6 months (as assessed by parental recall) is associated with decreased odds of asthma in Puerto Rican children, and that there is no additional beneficial effect of breastfeeding for over 6 months. These results support current recommendations on the duration of breastfeeding in an ethnic group at risk for asthma.

Long-term budesonide or nedocromil treatment, once discontinued, does not alter the course of mild to moderate asthma in children and adolescents

OBJECTIVES

To determine whether long-term, continuous use of inhaled anti-inflammatory medications affects asthma outcomes in children with mild to moderate asthma after use is discontinued.

STUDY DESIGN

Of the 1041 participants in the Childhood Asthma Management Program randomized clinical trial, 941 (90%) were followed to determine whether 4.3 years of twice-daily budesonide or nedocromil administration (each compared with placebo) affected subsequent asthma outcomes during a 4.8-year posttrial period in which treatment was managed by the participants' physicians.

RESULTS

The groups treated continuously during the trial with either budesonide or nedocromil did not differ from the group given placebo in terms of lung function, control of asthma, or psychological status at the end of 4.8 years of posttrial follow-up. However, the decreased mean height in the budesonide group relative to the placebo group at the end of the trial (1.1 cm; P = .005) remained statistically significant (0.9 cm; P = .01) after an additional 4.8 years and was more pronounced in girls (1.7 cm; P = .001) than in boys (0.3 cm; P = .49). Participants in all groups used inhaled corticosteroids during 30% of the posttrial period.

CONCLUSIONS

Clinically meaningful improvements in the control of asthma and in airway responsiveness achieved during continuous treatment with inhaled corticosteroids do not persist after continuous treatment is discontinued.

Breastfeeding and childhood asthma: a six-year population-based cohort study

Background

The question of the protective effect of breastfeeding on development of asthma has raised substantial interest, but the scientific evidence of the optimal duration of breastfeeding is controversial.

Methods

The authors elaborated the optimal duration of breastfeeding with respect to the risk of asthma primarily, and secondarily to the risk of persistent wheezing, cough and phlegm in school age in a population-based cohort study with the baseline in 1991 and follow-up in 1997. The study population comprised 1984 children aged 7 to 14 years at the end of the follow-up (follow-up rate 77). Information on breastfeeding was based on the baseline survey and information on the health outcomes at the follow-up.

Results

There was a U-shaped relation between breastfeeding and the outcomes with the lowest risk with breastfeeding from four to nine months for asthma and seven to nine months for persistent wheezing, cough and phlegm.

Conclusion

Our results suggest a U shape relation between duration of breastfeeding and risk of asthma with an optimal duration of 4 to 6 months. A true concave relation would explain the inconsistent results from the previous studies.

The link between obesity and asthma: a Canadian perspective

Asthma is considered to be more prevalent in obese subjects, and a possible causal link between these two entities has been suggested. In the present study, various observations on this relationship were reviewed, and an analysis of data obtained from the 2000 to 2001 Canadian Community Health Survey on the prevalence of self-reported asthma, medication use and allergy, according to body weight, was reported. Asthma medication use and self-reported asthma were more prevalent in the obese population, particularly in women. Mean body mass index was higher in the asthmatic population compared with the nonasthmatic population. Self-reported nonfood-related allergies were higher in the more obese subjects in the general population, but the prevalence of allergy was not different in obese asthmatic subjects compared with nonobese asthmatic subjects. Smoking did not seem to influence the relationship between asthma and body mass index. Further research should investigate the mechanisms by which obesity may influence the prevalence of asthma or asthma-like symptoms.

Primary prevention of allergy and asthma is possible

Allergic diseases, such as asthma, are the result of complex gene-environment interactions. The focus for prevention of allergic disease has been on environmental control. Environmental exposures begin during the intrauterine period, during which a T-helper-2 immune phenotype is promoted. Food allergy frequently occurs during the first year of life, and avoidance of exposure must begin in early pregnancy and must be complete to be effective. Partial avoidance strategies have not been successful. Current data do not allow us to specifically recommend breastfeeding for the prevention of allergy and allergic diseases, but for other important reasons, breastfeeding (particularly exclusive breastfeeding) should be encouraged for at least the first 4 mo of life. Sensitization to allergens is one of the strongest determinants for subsequent development of asthma. There is a strong relationship between exposure to house dust mites, allergen sensitization, and asthma. However, exposure to pets and animals in a farming environment early in life may actually be protective for the development of allergy and asthma. Specific recommendations relating to these exposures requires additional research, but genetics clearly plays an important role in that process. To date, only a multifaceted intervention program has been successful as a primary prevention strategy for the development of asthma in young children. The specific components of the multifaceted intervention and the duration of protection have not yet been defined. It is increasingly clear that gene-directed environmental manipulation undertaken in a multifaceted manner during a "window of opportunity" is critical in the primary prevention of allergy and allergic diseases like asthma.

Do risk factors for childhood infections and malnutrition protect against asthma? A study of Brazilian male adolescents

OBJECTIVES

We studied the association between early life conditions and asthma in adolescence.

METHODS

We conducted a population-based birth cohort study involving 2250 male 18-year-olds residing in Brazil.

RESULTS

Approximately 18% of the adolescents reported having asthma. Several childhood factors were found to be significantly associated with increased asthma risk: being of high socioeconomic status, living in an uncrowded household, and children being breastfed for 9 months or longer.

CONCLUSIONS

The present results are consistent with the "hygiene hypothesis," according to which early exposure to infections provides protection against asthma. The policy implications of our findings are unclear given that risk factors for asthma protect against serious childhood diseases in developing countries.

Exhaled nitric oxide is age-dependent in asthma

We determined whether the exhaled nitric oxide (eNO) level in asthmatics is age-dependent. Eighty-seven asthmatic patients aged 2-41 years were studied. Hyperreactivity to adenosine 5'-monophosphate (AMP) was used to confirm asthma (</= 200 mg/ml). In the younger group of children (2-5 years), AMP challenge was performed by the provocation concentration causing wheeze (PCW) method, while in the older groups of patients (6-41 years), regular spirometry was used. Exhaled NO was measured in the younger group by the tidal breathing method (TBm) and in the older subjects by the slow vital capacity method (SVCm). TBm and SVCm were compared in 21 other subjects, and there was a significant correlation between the two values (r = 0.96, P < 0.0001). The equation of correlation between the two methods was eNOTBm = 0.78eNOSVCm - 0.51. Within asthmatic patients, we found a significant increase in eNO with age (P < 0.0001), while there was no significant difference in AMP reactivity (P = 0.35). We conclude that eNO in asthmatic patients is age-dependent, with lower values in young children.

The prognosis of bronchial asthma in childhood in Hungary: a long-term follow-up

The aim of this study was to determine the prognosis of bronchial asthma in childhood in Hungary. One hundred and forty five adults (96 men and 49 women) with a clinical history of childhood bronchial asthma were examined at the age of 28 years or above (mean age 37.6, SD 5.9 years). The patients completed questionnaires concerning their asthmatic and accompanying allergic symptoms in childhood, at the age of 18 and at present. They were all prick-tested with 12 inhalant allergens. The results showed that 42.8% of the patients had become symptom-free, but 57.2% still had intermittent or persisting asthmatic symptoms in adulthood. More patients had intermittent day-time (59%) and night-time (67%) asthmatic symptoms than persistent symptoms (41% and 33%). Accompanying allergic diseases (rhinitis, conjunctivitis, dermal and gastrointestinal diseases, and drug andfood allergies) in childhood did not definitely affect the prognosis of the bronchial asthma. The proportion of females with allergic diseases increased, and among patients with skin diseases it was significantly higher than the proportion of affected males. At the age of 18, allergic rhinitis was more frequent than in childhood. The frequencies of other allergic disorders did not change significantly. In the patients with asthmatic symptoms, molds and cat-hair allergies were more frequent than in the symptom-free group. The long-term prognosis of bronchial asthma in childhood in Hungary is relatively good, but fewer than half of the patients became symptom-free. The complaints of most of the patients were mild, but one in seven of all the adults suffered from moderate or serious bronchial asthma. Household allergens may contribute to the persistence of asthmatic symptoms.

Expression of activation markers and cytokine mRNA by peripheral blood CD4 and CD8 T cells in atopic and nonatopic childhood asthma: effect of inhaled glucocorticoid therapy

HYPOTHESIS

Activated CD8 as well as CD4 T cells contribute to the production of asthma-relevant cytokines in both atopic and nonatopic childhood asthma.

OBJECTIVES

To measure the percentages of peripheral blood CD4 and CD8 T cells expressing naïve/memory (CD45RA/CD45RO) and activation (HLA-DR, CD25) markers, as well as mRNA-encoding interleukin-4 (IL-4) and interleukin-5 (IL-5) in atopic and nonatopic childhood asthmatics and in nonasthmatic controls matched for age and atopic status; and to study the effects of inhaled glucocorticoid therapy of the asthmatics on these measurements.

METHODS

Peripheral blood mononuclear cells were isolated from 17 atopic and 8 nonatopic stable (not acutely ill) asthmatics aged 7 to 16 years with moderate-to-severe disease and from 15 nonasthmatic controls matched for age and atopic status. Activation markers on CD4 and CD8 T cells were measured by flow cytometry, and expression of cytokine mRNA by in situ hybridization with CD4 and CD8 T cells were isolated using magnetic beads. Measurements were repeated in 18 of the asthmatics 4 to 6 months after initiation or escalation of inhaled glucocorticoid therapy for inadequately controlled asthma.

RESULTS

The percentages of CD4 T cells expressing CD45RO but not CD45RA were elevated in both asthma groups as compared with the relevant controls and were reduced in association with de novo or augmented inhaled glucocorticoid therapy. The percentages of CD8 T cells expressing both markers were not elevated in asthmatics as compared with controls. The percentages of both CD4 and CD8 T lymphocytes expressing HLA-DR and CD25 were elevated in the asthmatics as compared with controls, and significantly reduced in association with de novo or augmented inhaled glucocorticoid therapy. Elevated percentages of CD4 T cells expressing mRNA encoding IL-4 and IL-5, and CD8 T lymphocytes expressing IL-5, were found in asthmatics as compared with the controls. De novo or augmented inhaled glucocorticoid therapy was associated with significant reductions in the percentages of CD4 T cells expressing IL-5 and IL-4 mRNA, as well as improvements in lung function, symptom scores, and bronchial hyperresponsiveness to metacholine (PD20) in both the atopic and nonatopic asthmatics.

CONCLUSIONS

The data are consistent with the hypothesis that both activated CD4 and CD8 T cells are associated with child asthma, and that CD4 T cells make a greater contribution to IL-4 and IL-5 synthesis. Increased dosages of inhaled glucocorticoid resulted in clinical improvement in the asthmatics along with reduced T-cell activation and cytokine mRNA expression, suggesting a possible causal association.

Association between allergy and asthma from childhood to middle adulthood in an Australian cohort study

A cohort of 378 asthmatic children was studied from 7 to 35 yr of age at 7-yr intervals. On selection for inclusion in the study sample, the children had a wide range of severity of wheezing. At each 7-yr review, asthma severity, the presence of eczema or hay fever, and skin test reactivity to house dust mite or rye grass were recorded by questionnaire or clinical interview. We report on the course of asthma and these atopic conditions over the study period and discuss associations between the two phenomena. The presence of an atopic condition in childhood was found to increase the odds of more severe asthma in later life (odds ratio [OR] = 1.66, 95% confidence interval [CI]: 1.17 to 2.36 in the case of eczema; OR = 1. 39, 95% CI: 1.00 to 1.92 for hay fever; and OR = 2.25, 95% CI: 1.49 to 3.39 for skin test reactivity). Additionally, the odds of eczema and hay fever in later life increased with severity of asthma in childhood. The findings of this study provide substantially new quantitative information on the extent of association between asthma and atopic conditions from childhood into middle adulthood.

Is primary prevention of asthma possible?

The increased prevalence of asthma over the past quarter century has become a major public health problem for the industrialized world. Asthma is a disease process which has a strong heritable component which is impacted by multiple environmental factors. Given the rapid increase in asthma prevalence, it is difficult to ascribe the change to a genetic alteration. Therefore, the focus for understanding the changing prevalence of asthma must be on environmental factors. This article reviews factors which may contribute, in whole or in part, to the development of the disease process. In questioning whether it is possible to prevent development of a disease (primary prevention), it is critical to understand these factors. The environment may even have an impact on the fetus during intrauterine life. There does appear to be a "window of opportunity" in early life where a variety of factors, including food and inhalant allergen exposure, exposure to pollutants, and infection with both viral and bacterial agents, may be important in initiating the development of asthma and allergy. Potential approaches to primary prevention of asthma and allergy must consider each of these important factors. Given that asthma is a multifactorial disease with both complex genetic and environmental components, it is unlikely that any single intervention will significantly decrease the prevalence of asthma.

PEDIATRIC ALLERGY

The current paradigm of allergy pathogenesis is that allergy develops in individuals with a genetic predisposition only after they are exposed to allergens (Fig. 1). This hypothesis implies that factors in the environment can determine the initiation of allergic sensitization and can potentially influence the clinical manifestations and severity of disease. Because the prevalence of atopic diseases such as allergic rhinitis, asthma, atopic dermatitis, and food allergy have increased worldwide in the past several decades, and there is no mechanism for changes in population genetics over this short period of time, changes in the human environment are most likely responsible for these trends. From this line of reasoning, it follows that if the factors responsible for the increasing prevalence can be identified, then there would be an opportunity to develop strategies to reverse these trends. It also would be helpful to identify infants who are at risk for developing allergy, so that preventive strategies could be used most effectively.

In this article, studies to determine the contributions of genetics and the environment to the development of allergic diseases in childhood are explored. In addition, progress in identifying risk factors for allergy and preventive therapies for those children at risk are also addressed.

Evolution of asthma through childhood

The greatest incidence of childhood asthma is among males under 5 years, with decreasing numbers of new cases with age. Many young children wheeze, but remission is common especially in non-atopic children without a family history of allergy or asthma, whose wheezing relates more to infections and environmental tobacco smoke exposure. The prognosis of childhood asthma is best established from population studies, in which some two-thirds of wheezy children become symptom-free as adults, whereas follow-up studies of wheezing children seen in office or specialty clinic practice, who generally have more severe asthma, show a much greater likelihood (60-80%) of persistence of asthma into adulthood. Factors predisposing to persistence of childhood asthma include a positive family history, development of atopy, environmental exposures to allergens and cigarette smoke, markers of severity of childhood asthma, and female gender.

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.

Eczema, asthma and allergy

The literature in relation to the development of atopic and allergic disorders has been reviewed, in order to assess the claim that prolonged and exclusive breast feeding protects against the development of such disorders. The data in the literature show little consistent evidence to identify any protective association between breast feeding and either eczema, wheezing/asthma or other types of atopy or allergic response.

Prognostic factors for the outcome of childhood asthma in adolescence

By the second decade of life asthma symptoms often abate and it may seem that patients with mild asthma have "outgrown" the disease. Unfortunately this is likely to be the exception rather than the rule. Although the severity of asthma symptoms fluctuates with time, the inherited tendency towards respiratory symptoms never disappears and many teenagers who seem to be free of symptoms do, in fact, have persistent asthma. During symptom-free periods subclinical, but nevertheless significant, airways obstruction and/or bronchial hyperresponsiveness may be present. It is not unusual for adults who have been asymptomatic for a number of years to redevelope asthma symptoms. Indeed, much of the so-called adult onset asthma has its roots in childhood. Levison concluded that, in these subjects, it is often not the asthma that is outgrown but the paediatrician. The more severe asthma is in childhood the more likely it is that the disease will persist in adulthood. A complete list of the characteristics of the disease in childhood, and the potential risk factors associated with an unfavourable prognosis, such as pulmonary function and bronchial responsiveness and markers of airway inflammation, is therefore needed. As properly matched and controlled prospective long term studies have not been published it has not been possible to evaluate the effects on prognosis of any single class of antiasthma agent. Such studies are needed to find out if it is possible to alter the natural history of the disease. In theory modern asthma treatments, because they are able to improve symptoms and underlying disease phenomena, are also beneficial in the long term prognosis of childhood asthma. The majority of patients with persistent asthma included in the currently available studies were not receiving adequate treatment. Since compliance with therapeutic regimens in asthma, especially in adolescence, is low, a monitoring system is needed to guarantee adequate follow up and treatment during and beyond puberty.

Follow-up of asthma from childhood to adulthood: influence of potential childhood risk factors on the outcome of pulmonary function and bronchial responsiveness in adulthood

The outcome of asthma in 406 children, aged 8 to 12 years, was studied. Follow-up in adulthood was 86%, with a mean age of 24.7 years and a mean interval of follow-up of 14.8 years. The predictive value of gender and various childhood variables on the adult level of pulmonary function (forced expiratory volume in 1 second [FEV1]) and bronchial responsiveness in adulthood was assessed. An increase in mean percent predicted FEV1 from childhood to adulthood was found, both in subjects with (76%) and without (24%) current respiratory symptoms. The only childhood variable predictive of adult level of FEV1 was the level of percent predicted FEV1 (p < 0.01). The proportion of subjects with a histamine provocative concentration causing a 10% decrease in FEV1 less than or equal to 16 mg/ml decreased significantly in adulthood. The degree of bronchial responsiveness had increased slightly in adults with symptoms (p = 0.87), whereas it had decreased significantly in subjects without symptoms (p < 0.01). Female subjects were significantly more responsive in adulthood than male subjects (p = 0.047). The childhood degree of bronchial responsiveness significantly predicted the presence of bronchial responsiveness in adulthood (p = 0.02). We conclude that childhood percent predicted FEV1 is relevant to predict the outcome of the adult pulmonary function level, whereas female gender and the childhood degree of bronchial responsiveness are important for the prediction of adult degree of bronchial responsiveness among children with asthma.

Influence of asthma or allergies on the utilization of health care resources and quality of life of college students

The objectives of this study were to describe the treatment regimens of college students with asthma or allergies, to determine how asthma or allergies affect the lives of college students, and to evaluate the health care resources utilized by college students with asthma or allergies. A mail survey was sent to 275 students who received treatment for asthma or allergies at the Thomson Student Health Center at The University of South Carolina (TSHC-USC) during the fall 1991 semester. This survey, consisting of 46 questions, covered three key areas: current asthma or allergy management, class and work days missed, and utilization of health care resources. Students with "asthma and allergy" missed on average 2.4 days of class during the fall semester, whereas those with "asthma only" and "allergy only" missed on average 0.8 day and 1.5 days of class, respectively. Students with "allergy only" appeared to have a greater interference in their daily class and academic activities than students with "asthma and allergy" and "asthma only." In conclusion, students reported interference in their college activities and reported missing days of work and school because of asthma or allergies. This study also showed that a majority of these college students have not received asthma or allergy patient education nor utilized appropriate asthma or allergy management skills.

Childhood asthma: diagnosis and treatment

This discussion of asthma management should be regarded as providing guidelines, not dogma. The underlying principles of asthma management include recognition of the variability of the disease and the importance of the underlying inflammatory condition. Clinical assessment is not enough and objective monitoring with PEFR or spirometry provides important data. The treatment protocols require individualization. It is important that the patient and family are team members working together with the medical staff toward a goal of good asthma management. In the discussion of the management of asthma, much emphasis was placed on spirometry and home measurement of PEFR. Office use of spirometry is now the norm for asthma management. Providing asthmatic patients with peak flow meters and instructions in their use is part of the routine care of asthma. Instruction of the patient and family in the proper use of medications is paramount. The MDI devices need to be prescribed with careful instructions regarding their use. When the patient comes in for follow-up, part of the examination should include the patient's demonstration of how he uses this device. Discussion of the proper and safe use of bronchodilators is important. Overuse of inhaled bronchodilators may be a reflection of increasing asthma or, at the very least, evidence that the patient does not understand appropriate treatment of asthma. If a patient is dependent on regular use of an inhaled beta agent, it is likely that he would benefit from therapy directed at the underlying inflammation of asthma. The patient and the family should understand the purpose of each medication, the side effects, and the risks and benefits of their use. In particular, if steroid medications are necessary, the reasons for their use should be explained. Carefully matching the severity of the asthma with the therapeutic protocols provides an organized approach to asthma treatment. Avoiding triggers of asthma and controlling the environmental exposure to potential triggers leads to lower medication requirements and less lability. Offering the family written instructions to cope with changes in the child's condition, based on assessment of clinical and PEFR observations, allows them more autonomy and comfort in the day-to-day care of the asthmatic child.

The effects of airway hyperresponsiveness, wheezing, and atopy on longitudinal pulmonary function in children: a 6-year follow-up study

We examined growth of spirometric lung function in 696 children of European ancestry who were followed from ages 9 to 15 years and stratified according to their degree of responsiveness to methacholine inhalation challenge, atopic status, and respiratory symptoms. Subjects were participants in the longitudinal Multidisciplinary Health and Development Study in Dunedin, New Zealand. Forced expired volume in 1 second (FEV1), and vital capacity (VC) were measured at 9, 11, 13, and 15 years of age, concurrently with assessment of airway responsiveness determined by the concentration of methacholine causing a 20% fall in FEV1 (PC20 FEV1). Atopic status was assessed at age 13 by skin-prick testing to 11 allergens. In children demonstrating airway hyperresponsiveness, FEV1 increased with age at a slower rate, and the FEV1/VC ratio had a faster rate of decline through childhood, compared to non-responsive children. Subjects with positive skin tests to house dust mite and cat dander also had lower mean FEV1/VC ratios than the control group. Any reported wheezing was associated with slower growth of FEV1 and VC in males. We conclude that in New Zealand children with airway responsiveness and/or atopy to house dust mite or cat growth of spirometric lung function is impaired.

Influence of a positive family history and associated allergic diseases on the natural course of asthma

The outcome of childhood asthma was studied in a cohort of 406 asthmatic children, with emphasis on the influence of family history for allergic disease, as well as the influence of associated allergic diseases on prognosis. Sixty-two per cent had a positive family history for atopy. In young adulthood no differences, either in symptoms or lung function were demonstrated in comparison to subjects with a negative family history. Fifty-two per cent of the children had no other allergic disease, 48% had either eczema or hay fever or both. When subjects were stratified based on associated allergic disease, no differences in outcome in adulthood were revealed either. It is concluded that neither a positive family history, nor concurrent associated allergic diseases in the child contribute to the prognosis of asthma from childhood to young adulthood. Therefore, environmental factors as well as patient characteristics (including lung function level, level of bronchial responsiveness) are likely to be more important for the prognosis.

Sensitivity to common allergens: relation to respiratory symptoms and bronchial hyper-responsiveness in children from three different climatic areas of Australia

In order to examine further the relation between atopy, as defined by skin-prick tests, and respiratory illness, we studied three populations of schoolchildren aged 8-11 years and living in different climatic areas of New South Wales, Australia. Skin-prick tests were performed using 13 commercial allergen extracts. Respiratory and allergic symptoms were assessed using a self-administered questionnaire to parents and bronchial hyper-responsiveness (BHR) was measured by histamine inhalation test. We defined current asthma as BHR together with symptoms of wheeze in the 12 months prior to study. Children with one or more positive skin weals of greater than or equal to 3 mm had significantly more recent wheeze, hayfever, eczema and BHR than children with smaller weals (P less than 0.001). In each area, 95-97% of all atopic children were sensitized to one of the following seven allergens: house dust, Dermatophagoides farinae, D. pteronyssinus, cat dander, plantain, rye grass, and Alternaria tenuis. Thus, these seven selected allergen extracts and a skin weal of 3 mm could be used to detect clinically relevant atopy in these populations of children. Sensitivity to house dust mite had the strongest independent association with current asthma in all three areas. The associations of other allergen sensitivities with BHR or current asthma were area dependent, indicating the influence of local allergen levels on respiratory illness in children. The potency of house dust mite sensitivity in increasing the risk of children having BHR and current asthma is confirmed.

Assessment and prediction of asthma and its severity in the pediatric community

Seventy four asthmatic children aged 7 to 11 years were examined along with controls matched by age and sex. Clinical and laboratory investigations preceded a 28-day follow-up where data about morning and evening peak expiratory flow rate (PEF), symptoms and treatment were recorded. The coefficient of variation of PEF was found to be an objective measurement of asthma severity that has statistically significant correlation with both symptoms (rs = .36) and treatment (rs = .60). Moreover, it separates mild and severe asthmatics, as confirmed by statistically significant differences (p = .008 or less) in symptoms, treatment, skin allergy and airways response to exercise. Skin allergy and airways responsiveness to exercise were found to be predictors of both disease and severity. By means of logistic regression analysis it was possible to establish the probabilities for both asthma and severe asthma when children presenting and not presenting these characteristics are compared. One single positive skin test represent a probability of 88% for the development of asthma and a probability of 70% for severe disease. A PEF reduction of 10% after an exercise test implies a probability of 73% for disease and a probability of 64% for severe disease. Increases in these variables imply geometrically increased risks and their presence together have a multiplicative effect in the final risk.

The natural history of IgE sensitisation and atopic disease in early childhood

We have prospectively followed 57 children of atopic parents up to 5 years of age, documenting clinical atopic disease and allergen skin test reactions. The cumulative prevalences of the clinical features of atopic disease over the 5 years were: atopic dermatitis (58%), wheeze (49%), recurrent wheeze (33%), rhinitis (68%) and immediate food reactions (18%). Atopic dermatitis and immediate food reactions predominated in infancy (birth to 20 months) while wheezing was more prominent in later childhood (20 months to 5 years). Rhinitis was common in both infancy and childhood. IgE sensitisation to ingested allergens was prominent in early infancy and was usually transient. Inhaled allergen sensitisation occurred later in infancy and was generally permanent with wheal sizes tending to increase with age. There was a significant association between IgE sensitisation to ingested but not inhaled allergens and all atopic manifestations in infancy, with the exception of rhinitis. In contrast IgE sensitisation to inhaled allergens was associated with rhinitis and wheeze in later childhood. We found two clinical groups. One group, with only ingested allergen sensitisation had a high incidence of atopic dermatitis but low incidence of respiratory symptoms at 5 years of age. The other group, who developed evidence of IgE sensitisation to inhaled allergens, had a high incidence of rhinitis and wheeze but low incidence of atopic dermatitis at 5 years of age.

Bronchial hyperresponsiveness in two populations of Australian schoolchildren. II. Relative importance of associated factors

In a cross-sectional study of 2363 schoolchildren living in two rural areas of New South Wales, we used a questionnaire to collect details of sex, area of residence, social class, early respiratory illness (ERI), parental history of asthma and recent upper respiratory tract infection (URTI), and we used skin-prick tests to measure atopic status. The relative importance of these factors on the likelihood of children having bronchial hyperresponsiveness (BHR) was assessed using a linear modelling analysis. The extent to which these factors affected the severity of BHR was also examined. We found that social class or recent URTI had no association with BHR, that sex and area of residence (inland or coastal) had a small association and that a history of early respiratory illness, a history of asthma in either parent, and atopic status had an important association with BHR. Atopic status was the most important factor. The proportion of children with atopy, with ERI or with parental asthma increased as the severity of BHR increased. The odds ratio for moderate or severe BHR doubled if either ERI or parental asthma was present in addition to atopy and there was a six-fold increase if all three factors were present together. The identification of these risk factors makes it possible to predict which children in the community are most likely to have BHR, and which children are at high risk for having more severe levels of BHR.

Childhood asthma in adult life: a further study at 28 years of age

A group of 323 subjects who had wheezed in childhood and 48 control subjects of the same age were studied prospectively from 7 to 28 years of age. A classification system based on wheezing frequency was found to correlate well with clinical and spirometric features of airway obstruction. The amount of wheezing in early adolescence seemed to be a guide for severity in later life with 73% of those with few symptoms at 14 continuing to have little or no asthma at 28 years. Similarly 68% of those with frequent wheezing at 14 still suffered from recurrent asthma at 28 years. Most subjects with frequent wheezing at 21 continued to have comparable asthma at 28 years. Of those with infrequent wheezing at 21, 44% had worsened at 28 years. Women fared better than men between 21 and 28 with 19% having worse symptoms compared with 28% of men. Treatment at all ages was generally inadequate. The number of smokers among those with asthma was of concern.

Long-term changes in inhalant allergy in asthmatic children

In a representative cohort of 55 asthmatic schoolchildren the progress of the allergy per se was followed up prospectively for 8 years. Judged by clinical data, skin prick tests and RAST, a large majority of the children retained their allergies to pollen and animal danders. These allergens were predominant, whereas allergy to mites and moulds was less frequent. Serum IgE levels showed a strong tendency to remain high. Positive RAST and skin prick tests were also found in a substantial number of children with normal serum IgE concentrations.

Special features of asthma in children

Asthma in children has many special features which deserve consideration. This disease is probably underdiagnosed and is often undertreated. Vague, persistent respiratory symptoms, especially chronic cough, may often be due to asthma. Chronic bronchitis is extremely rare in the pediatric patient and is a manifestation of reactive airway disease or cystic fibrosis. The absolute severity, the extent of the disease, responses to treatment, and long-term course should be evaluated by repeated pulmonary function tests. Fortunately, asthma responds well to pharmacologic and supportive therapy, and it is important to approach its management as that of a chronic rather than episodic illness. Therapy should include comprehensive, closely supervised drug therapy, health education, and a program of self-management. Asthma usually starts before youngsters enter school, and the majority get better as they get older. Nevertheless, many children with moderate or severe asthma will continue to be troubled by intermittent or chronic airway obstruction into adulthood, and they require long-term, anticipatory treatment programs. Comprehensive care will optimize the quality of life for the affected children and their families, and it will minimize the discomfort and restrictions to which some of them have been subjected unnecessarily. Asthma in childhood, especially when not well controlled, may constitute a risk factor for the development of chronic obstructive pulmonary disease in adulthood; however, this is as yet only suspected and not proved.