Natural history of bronchial asthma in childhood. A prospective study from birth up to 12-14 years of age

Sensitization to Inhaled Allergens in Atopic Children in Jordan Capital, Amman: A Cross-sectional Study

Background:

As the prevalence of allergic diseases is increasing all over the world, it is vital to identify the specific allergens, which contribute to the development and persistence of such conditions.

Objectives:

This study aims to assess the prevalence of aeroallergen sensitization and, to evaluate the profile of skin prick test among atopic Jordanian children who are visiting Jordan University Hospital (JUH).

Methods:

A retrospective analysis of all Skin Prick Test (SPT) and results of atopic children and adolescents aged (1.5-18 years) who visited the pediatrics clinics at JUH from January 2018 until December 2019.

Results:

Over two years, a total of 171 children (male: female ratio of 1.9) with a median age of 6.2 years (1.5-18) were subjected to SPT. One hundred and seven children (62.5%) were found to be sensitized to at least one of the ten aeroallergen extracts tested. The most common sensitizations were to olive pollen (45.6%), Mites Dermatophagoides Petronyssinus (42.0%), and Dog Dander (38.6%). The highest sensitization rate was among the age group 2-4 years (28.1%). The sensitization rates increased in conjunction with an increase in age in the first age groups (preschool and school-age groups).

Conclusion:

The study’s findings provide an understanding of the locally prevalent aeroallergens, yet a multi-center review would be more useful for creating an optimized SPT panel specific to the Jordanian pediatric population.

Risk Factors for Wheezing in Primary School Children in Bursa, Turkey

Background

Wheezing is the most common symptom of childhood respiratory tract illnesses. It is important not only for its associated acute morbidity, but also for the fact that early childhood wheezing confers a high risk for asthma. Epidemiological studies from various countries show that 10–15% of children <1 year of age and 25% of children <5 years of age have wheezing-associated respiratory tract illness, and one-third of these children develop asthma later in life.

Methods

In this retrospective study, we evaluated the association between a history of wheezing and prenatal, postnatal, familial, and environmental risk factors in 858 7-year-old children, randomly selected from seven primary schools in Bursa, Turkey, by means of an easy-to-understand questionnaire form. Among these children, 12.4% had a history of early transient wheezing, 7.1% had persistent wheezing, and 7.7% had late onset wheezing; 72.8% had no wheezing symptoms and 33.3% of children who experienced wheezing during the first 3 years of life had physician-diagnosed asthma.

Results

Notable risk factors associated with wheezing were as follows: male gender, lower socioeconomic status, premature birth, maternal smoking during pregnancy, bottle-feeding before 2 months of age, dampness and mold at home, hospitalization due to any respiratory illness in infancy, history of croup between 6 months and 5 years of age, frequent upper respiratory infections during the first 3 years of life, allergic eczema in the child, and any allergic disease in the mother or siblings.

Conclusion

This study shows that the high rates of reported wheezing in the 858 primary school children in Bursa are clearly attributable to important risk factors that have long been recognized and discussed by researchers worldwide, and this suggests that all efforts at primary prevention may be insufficient.

Effect of season of birth on cord blood IgE and IgE at birth: A systematic review and meta-analysis

BACKGROUND

Elevated cord blood IgE is important on the pathway to allergic disease. The association between season of birth and infant cord blood IgE is not well-established. Study findings differ on which birth season is associated with higher cord blood IgE risk and its magnitude. We conducted a systematic review and meta-analysis of studies on season of birth and cord blood IgE.

METHODS

We searched Medline, Web of Science, Scopus and ProQuest Health databases, and reviewed reference lists of articles that met the inclusion criteria. All included studies measured IgE as a binary variable using various cut-off values. We performed multivariate-random-effects meta-analysis to handle an exposure with multiple categories of Season of Birth.

RESULTS

Our search identified 275 records and 10 had sufficient data to be included in a meta-analysis. Relative to summer, winter birth had the greatest odds of high IgE (≥ 0.1IU/ml), meta-analysis OR = 1.24 (95%CI: 1.01-1.52). A similar OR, was found for IgE ≥ 0.5 IU/ml, OR = 1.30 (95%CI: 0.99-1.71).

CONCLUSIONS

A winter season of birth was associated with statistically significant higher odds of elevated cord blood IgE at cut-off ≥ 0.1IU/ml but borderline at cut-off ≥ 0.5IU/ml. This winter effect is likely to be a marker for a range of other environmental exposures during specific stages of pregnancy, such as aeroallergen exposures, maternal infections and vitamin D levels. Further research is required to support our finding and to identify the exact mechanisms that lead to the winter season of birth effect on circulating IgE levels, as this may have implications for allergic disease prevention.

Impact of a short early therapeutic education program on the quality of life of asthmatic children and their families

OBJECTIVES

Few studies have been made on the impact of therapeutic education (TE) on the quality of life (QOL) of asthmatic primary-school aged children. We attempted to assess the beneficial effects on the QOL of children and their parents of a short TE program initiated immediately after the first consultation with a pediatric pulmonologist.

METHODS

The QOL of 31 families of asthmatic children (aged 5-11) was measured before and 3 months after a short and early programme of TE by the French version of the Pictured Child's Quality of Life Self Questionnaire (AUQUEI, AUtoquestionnaire QUalité de vie Enfant Imagé) for the children, and by the Paediatric Asthma Caregiver's Quality of Life Questionnaire (PACQLQ) for the parents. The other criteria studied were asthma management, school and workplace absenteeism and functional respiratory parameters.

RESULTS

TE did not significantly alter the AUQUEI score (P = 0.67). No change was observed in the different areas studied: autonomy (P = 0.97), leisure activities (P = 0.64), functions (P = 0.88), and social relations (P = 0.51). In contrast, the PACQLQ score considerably improved after TE (P < 0.001), as evidenced by reduced activity limitations (P < 0.001) and improved emotional functioning of parents (P < 0.001). These results were accompanied by a significant improvement in asthma management, with, in particular, a major decrease in the use of medication (P < 0.001) and the number of unscheduled medical consultations (P < 0.001) and visits to the emergency department (P = 0.02); a decrease in school absenteeism (P = 0.009); and an improvement in forced expiratory volume in 1 sec (FEV₁ ) (P = 0.05).

CONCLUSIONS

Our TE program had rapid and beneficial effects on numerous objective and subjective parameters, thereby contributing to the well-being of the families and probably to a subsequent decrease in the overall cost of asthma management. Pediatr Pulmonol. 2015; 50:213-221. © 2014 Wiley Periodicals, Inc.

Can family history and cord blood IgE predict sensitization and allergic diseases up to adulthood?

BACKGROUND

Long-term studies of the predictive value of family history and cord blood IgE level until adulthood are few, and their conclusions have been contradictory.

METHODS

Screening of total IgE in 1617 cord blood samples was performed in a Danish birth cohort. All infants with cord blood IgE (CB-IgE) ≥ 0.5 kU/l and a corresponding randomly chosen group with CB-IgE <0.5 kU/l were chosen for follow-up. Questionnaire-based interviews, physical examination, specific IgE testing, and from 10 yr also spirometry, were carried out at 1½, 5, 10, 15, and 26 yr. Predefined diagnostic criteria were used.

RESULTS

A total of 455 infants were included, 188 with CB-IgE ≥ 0.5 kU/l and 267 with CB-IgE <0.5 kU/l. Follow-up rates were high, 288 (63%) attended the 26-yr follow-up. Family history and elevated CB-IgE were significantly associated to allergic disease until 26 yr. Concerning any allergic symptoms at 1½ yr the positive and negative predictive values (PPV and NPV), the sensitivity and specificity of CB-IgE ≥ 0.5 kU/l, was 29%, 81%, 54%, and 61%, respectively. The corresponding figures at 26 yr were 46%, 62%, 43%, and 65%. Overall, family history as well as CB-IgE ≥ 0.5 kU/l was associated with high NPV and specificity, but low PPV and sensitivity.

CONCLUSION

Although family history and elevated CB-IgE were significantly associated with primarily atopic disease until 26 yr, none of these were strong predictors for subsequent sensitization and allergic symptoms from childhood until early adulthood. It appears that the predictive capacity of CB-IgE decreases in adolescence and early adulthood.

Prevalence and clinical profile of difficult-to-control severe asthma in children: results from pneumology and allergy hospital units in Spain

BACKGROUND

Severe asthma is often poorly controlled and its prevalence in Spanish children is unknown. The aim was to determine the prevalence of difficult-to-control severe asthma in children, the agreement of asthma control between physicians and Spanish Guidelines for Asthma Management (GEMA), and the health-related quality of life (HRQoL) for children and parents.

METHODS

Observational, cross-sectional, two-phase, multicentre study. In the first phase, all children who attended pneumology and allergy units during a three-month period were classified according to physicians' criteria as patients with: asthma, severe asthma, or difficult-to-control severe asthma. Patients aged 6-14 years with severe asthma (difficult-to-control or controlled) were included in the second phase.

RESULTS

12,376 asthmatic children were screened in the first phase. According to physicians' criteria, 8.8% (95% CI 8.3-9.3%) had severe asthma. Of these, 24.2% (95% CI, 21.7-26.8%) had difficult-to-control severe asthma. 207 patients with severe asthma (mean age 10.8 ± 2.3 years; 61.4% male; mean of 5.5 ± 3.4 years since asthma diagnosis) were included in the second phase. Compared to the patients with controlled asthma, children with difficult-to-control asthma had a higher number of exacerbations, emergency room or unscheduled primary care visits in the previous year (p<0.0001, all) and poor HRQoL (p<0.0001, both children and caregivers). 33.3% of patients with controlled asthma according to physicians' criteria were poorly controlled according to GEMA.

CONCLUSIONS

Around one in four asthmatic children with severe disease had difficult-to-control asthma, although one third was underestimated by physicians. Children with difficult-to-control severe asthma had a poor HRQoL that also affected their parents.

Irreversible airway obstruction in asthma: what we lose, we lose early

Asthma, a syndrome manifested by airway inflammation and obstruction, globally contributes significantly to morbidity and mortality. Although current evidence identifies risk factors that evoke asthma, critical questions concerning susceptibility factors that induce severe persistent disease remain unclear. Early onset of asthma decreases lung function that may be unrecognized until later in adulthood when patients experience dyspnea on exertion and attenuated quality of life. This review highlights current evidence in predicting the onset of asthma and identifying those patients at greatest risk for severe persistent disease.

Asthma Heredity, Cord Blood IgE and Asthma-Related Symptoms and Medication in Adulthood: A Long-Term Follow-Up in a Swedish Birth Cohort

Cord blood IgE has previously been studied as a possible predictor of asthma and allergic diseases. Results from different studies have been contradictory, and most have focused on high-risk infants and early infancy. Few studies have followed their study population into adulthood. This study assessed whether cord blood IgE levels and a family history of asthma were associated with, and could predict, asthma medication and allergy-related respiratory symptoms in adults. A follow-up was carried out in a Swedish birth cohort comprising 1,701 consecutively born children. In all, 1,661 individuals could be linked to the Swedish Prescribed Drug Register and the Medical Birth Register, and 1,227 responded to a postal questionnaire. Cord blood IgE and family history of asthma were correlated with reported respiratory symptoms and dispensed asthma medication at 32-34 years. Elevated cord blood IgE was associated with a two- to threefold increased risk of pollen-induced respiratory symptoms and dispensed anti-inflammatory asthma medication. Similarly, a family history of asthma was associated with an increased risk of pollen-induced respiratory symptoms and anti-inflammatory medication. However, only 8% of the individuals with elevated cord blood IgE or a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication at follow-up. In all, 49 out of 60 individuals with dispensed anti-inflammatory asthma medication at 32-34 years of age had not been reported having asthma at previous check-ups of the cohort during childhood. Among those, only 5% with elevated cord blood IgE and 6% with a family history of asthma in infancy could be linked to current dispensation of anti-inflammatory asthma medication as adults. Elevated cord blood IgE and a positive family history of asthma were associated with reported respiratory symptoms and dispensed asthma medication in adulthood, but their predictive power was poor in this long-time follow-up.

The relationship of season of birth to asthma and allergy in urban African American children from 10 to 13 years of age

OBJECTIVES

To assess the relationship between season of birth and presence of asthma and allergy in preteen, low-income, African American children.

METHODS

The study consisted of a self-administered survey followed by telephone interviews of parents of children attending 19 middle schools in Detroit, Michigan. Out of 4194 children, 1292 were identified with asthma and 962 parents of these children provided informed consent and took part in telephone interviews.

RESULTS

No statistically significant relationships were observed between season of birth and diagnosis of asthma (p > .05) or with diagnosis adjusting for income, age, gender, parent's education, or parent being a smoker (p > .05). No statistically significant association was evident between season of birth and presence of allergy (p > .05) or with allergy adjusting for the above variables (p > .05).

CONCLUSIONS

Identifying children vulnerable to problems with asthma and allergy, especially in populations exhibiting high prevalence of the conditions and significant disparities in outcomes, requires use of all possible means. Season of birth does not appear to be a useful indicator in identification of such children. The findings from this study do not support the proposition that season of birth, associated with early exposure to viruses as evident in the winter and to seasonal allergens, contributes to more asthma and/or allergy.

Forced oscillation technique and childhood asthma

Most infants and preschool children are not able to voluntarily perform the physiological maneuvers required to complete the pulmonary function tests that are used in adults and older children. Recently, commercial devices using forced oscillation technique (FOT) suitable for young children have become available. In devices with FOT, an oscillation pressure wave is generated by a loud speaker, is applied to the respiratory system, usually at the mouth, and the resulting pressure-flow relationship is analyzed in terms of impedance (Zrs). Zrs encompasses both resistance (Rrs) and reactance (Xrs). Rrs is calculated from pressure and flow signals, and is a measure of central and peripheral airway caliber. Xrs is derived from the pressure in the phase with volume and is related to compliance (Crs) and inertance (Irs). These parameters individually indicate the condition of the small and large airways in each patient and indirectly suggest the presence of airway inflammation. It is agreed that the clinical diagnostic capacity of FOT is comparable to that of spirometry. One of the advantages of FOT is that minimal cooperation of the patient is needed and no respiratory maneuvers are required. The use of FOT should be considered in patients in whom spirometry or other pulmonary function tests cannot be performed or in cases where the results of other tests appear to be unreliable. In addition, this approach is effective in assessing bronchial hyperresponsiveness. Considering these qualities, FOT is a useful method to study pulmonary function in preschool children with asthma.

Happy air®, a successful school-based asthma educational and interventional program for primary school children

BACKGROUND

To investigate whether an active partnership between schools, parents, and pediatricians can improve the management of asthma and quality of life of children with asthma.

METHODS

A comprehensive asthma program (Happy Air®), based on a strong family-physician-school relationship, was carried out over a period of 3 years in six primary schools (2765 children). This program provides educational intervention to families, school staff, and students, as well as the administration of written questionnaires to identify children with asthma, asthma diagnosis and management, and, last but not least, extracurricular activities to improve respiratory and psychological conditions. Quality of life of children and parents, at the beginning and end of the program, was assessed using PedsQL™ 4.0 (Pediatric Quality of Life Inventory) measurement model.

RESULT

Asthma was diagnosed in 135 children, of which 37 (27%) were diagnosed de novo. In all children, both single item and total clinical asthma scores showed a significant increase (p < .001) at the end of the Happy Air® program. The average scores of both the total PedsQL™ 4.0 and the four Scales were significantly increased (p < .001).

CONCLUSION

Happy Air® is a model for a strategy of education- and school-based intervention for children with asthma and their families. This multi-action program for diagnosis, clinical follow-up, education, self-management, and quality-of-life control aims to minimize the socioeconomic burden of asthma disease.

Asthma prediction in school children; the value of combined IgE-antibodies and obstructive airways disease severity score

BACKGROUND

Allergic sensitisation increases the risk for asthma development. In this prospective birth cohort (Environment and Childhood Asthma) study, we hypothesized that combining quantitative measures of IgE antibodies (Sigma-IgE) and Severity score of obstructive airways disease (OAD) at 2 years of age (Severity score) is superior to predict current asthma (CA) at 10 years than either measure alone. Secondarily, we assessed if gender modified the prediction of CA.

METHODS

A follow-up study at 10 years of age was performed in 371 2-year-old children with recurrent (n = 219) or no (n = 152) bronchial obstruction with available serum analysed for Sigma-IgE to common food and inhalant allergens through a panel test, Phadiatop Infant) (Phadia, Uppsala, Sweden). Clinical variables included allergic sensitisation and exercise testing to characterise children with CA vs not CA at 10 years and the Severity score (0-12, 0 indicating no OAD) was used to assess risk modification.

RESULTS

Severity score alone explained 24% (Nagelkerke R(2) = 0.24) of the variation in CA, whereas Sigma-IgE explained only 6% (R(2) = 0.06). Combining the two increased the explanatory capacity to R(2) = 0.30. Gender interacted significantly with Sigma-IgE; whereas Severity score predicted CA in both genders, the predictive capacity of Sigma-IgE for CA at 10 years was significant in boys only.

CONCLUSION

Combining Sigma-IgE to inhalant allergens and Severity score at 2 years was superior to predict asthma at 10 years than either alone. Severity score predicted CA in both genders, whereas Sigma-IgE significantly predicted CA in boys only.

Projections of the effects of climate change on allergic asthma: the contribution of aerobiology

Climate change is unequivocal and represents a possible threat for patients affected by allergic conditions. It has already had an impact on living organisms, including plants and fungi with current scenarios projecting further effects by the end of the century. Over the last three decades, studies have shown changes in production, dispersion and allergen content of pollen and spores, which may be region- and species-specific. In addition, these changes may have been influenced by urban air pollutants interacting directly with pollen. Data suggest an increasing effect of aeroallergens on allergic patients over this period, which may also imply a greater likelihood of the development of an allergic respiratory disease in sensitized subjects and exacerbation of symptomatic patients. There are a number of limitations that make predictions uncertain, and further and specifically designed studies are needed to clarify current effects and future scenarios. We recommend: More stress on pollen/spore exposure in the diagnosis and treatment guidelines of respiratory and allergic diseases; collection of aerobiological data in a structured way at the European level; creation, promotion and support of multidisciplinary research teams in this area; lobbying the European Union and other funders to finance this research.

Fungi and pollen exposure in the first months of life and risk of early childhood wheezing

BACKGROUND

Many studies have found that the risk of childhood asthma varies by month of birth, but few have examined ambient aeroallergens as an explanatory factor. A study was undertaken to examine whether birth during seasons of elevated ambient fungal spore or pollen concentrations is associated with risk of early wheezing or blood levels of Th1 and Th2 type cells at 24 months of age.

METHODS

514 children were enrolled before birth and followed to 24 months of age. Early wheezing was determined from medical records, and Th1 and Th2 type cells were measured in peripheral blood using flow cytometry. Ambient aeroallergen concentrations were measured throughout the study period and discrete seasons of high spore and pollen concentrations were defined.

RESULTS

A seasonal pattern was observed, with birth in autumn to winter (the spore season) associated with increased odds of early wheezing (adjusted odds ratio 3.1; 95% confidence interval 1.3 to 7.4). Increasing mean daily concentrations of basidiospores and ascospores in the first 3 months of life were associated with increased odds of wheeze, as were increasing mean daily concentrations of total and specific pollen types. Levels of Th1 cells at age 24 months were positively associated with mean spore concentrations and negatively associated with mean pollen concentrations in the first 3 months of life.

CONCLUSIONS

Children with higher exposure to spores and pollen in the first 3 months of life are at increased risk of early wheezing. This association is independent of other seasonal factors including ambient levels of particulate matter of aerodynamic diameter <or=2.5 microm and lower respiratory infections.

Factors affecting bronchial hyperreactivity in asthmatic children

Bronchial hyperresponsiveness (BHR), the exaggerated airway narrowing in response to nonspesific stimuli, is a common characteristic of asthma. One hundred thirty-five children who were diagnosed asthma in the outpatient clinic of Gazi University Hospital, Pediatric Allergy and Asthma Department between January 2007 and January 2008 were retrospectively analysed from the asthma database of the division. BHR was not found to be different according to sex. Younger the age of the patient, more severe was BHR (p = 0.096, r = 0.164). Younger the age at onset of the symptoms, the more severe was the BHR (p < 0.001, r = 0.307). Patients who had an asthmatic first degree relative and who were exposed to passive smoking at home, had more severe BHR (p = 0.006 and p = 0.032, respectively). There were more hospitalizations among the asthmatic children with moderate-severe BHR (p = 0.027) however no correlation was found between chronic asthma severity and the degree of BHR). In this study we found that age, age at onset of symptoms, having a parent with asthma, exposure to tobacco smoke and baseline lung function are related to BHR measured at referral. Serum levels of Ig E or skin prick test positivity were not found to have any effect on BHR severity. Considering BHR severity, we could not reveal any relation between atopic and nonatopic children. However among atopic subjects, the ones with indoor allergen sensitization had more severe BHR.

Timeliness of diagnosis of asthma in children and its predictors

BACKGROUND

There is a paucity of literature using medical records to evaluate the timeliness of asthma diagnosis in children and the predictors associated with timeliness of asthma diagnosis.

METHODS

Subjects were obtained from a convenience sample of 839 children, aged 5-13 years. We conducted comprehensive medical record reviews for these children to determine their asthma status by applying predetermined criteria for asthma. Predictors were evaluated for an association with timeliness of asthma diagnosis.

RESULTS

Of 839 children, 276 children met the criteria for asthma before 18 years of age. Of these subjects, 97 had timely diagnosis of asthma while 179 did not have timely diagnosis of asthma with the median delay of 3.3 years. Children with definite asthma at the time of index date was three times more timely to be diagnosed with asthma [hazard ratios (HR) 3.3, 95% CI: 2.43-4.47, P < 0.001], compared to those with probable asthma. Children with a family history of asthma were more timely to be diagnosed with asthma (HR 1.36, 95% CI: 1.03-1.8, P = 0.031). Children with exercise-induced wheezing or bronchospasm were more timely to be diagnosed with asthma (HR 1.79, 95% CI: 0.95-3.36, P = 0.07), compared to those with spasmodic (or bronchospastic) cough.

CONCLUSIONS

Many asthmatic children are not diagnosed with asthma in a timely manner, especially in those without the commonly recognized factors associated with asthma. Health care providers need to be reminded that asthma can still occur in those without commonly recognized risk factors. Asthma guidelines need to emphasize this aspect.

Characterization of the duration from onset of asthma symptoms to asthma disease

BACKGROUND

Little is known about factors associated with progression of childhood asthma from onset of symptoms to index date determined by medical records.

OBJECTIVE

To determine the duration between the onset of asthma symptoms to index date of asthma (ie, time when one met the criteria for asthma) and associated factors.

METHODS

Study participants came from a sample of 839 healthy children, aged 5 to 12 years, who had participated in a previous study. Comprehensive medical record reviews were conducted to determine first documentation of asthma symptoms and index date of asthma. Factors were evaluated for an association with the duration from onset of asthma symptoms to index date of asthma.

RESULTS

Of the study sample, 222 children met the criteria for asthma and had an available onset date of asthma symptoms. The median ages at onset of asthma symptoms and the index date were 5.6 and 7.6 years, respectively. The median duration between onset of asthma symptoms and index date was 2.9 months, and the mean was 17.2 months. There was a tendency for patients with a pet at home (P = .047), exercise-induced symptoms (P = .04), younger age at symptom onset (P = .05), and more severe asthma (P = .05) to have a shorter duration from onset of symptoms to index date.

CONCLUSIONS

The duration from onset of asthma symptoms to index date of asthma varies significantly depending on host and environmental factors. It does not necessarily correlate with commonly recognized risk factors for incidence or severity of asthma.

[Epidemiology of allergic respiratory disorders in infants]

INTRODUCTION

Allergic disorders of the respiratory tract have been the subject of many epidemiological studies, especially during infancy which is known to be a critical period for development of the immune system. This paper aims to describe the prevalence of allergic respiratory disorders in children below three years of age in the general population, despite the lack of shared definition of asthma and allergic rhinitis among studies.

STATE OF ART

Doctor-diagnosed asthma occurs in 5% of children below two years of age. One third of children below three years of age experience wheeze during a lower respiratory tract infection, but only 7% of children wheeze apart from a respiratory infection. Asthma-like cough and bronchial obstruction symptoms are reported in respectively 15% and 9% of children below two years of age. Depending on the definition of allergic rhinitis used, its prevalence varies from 1 to 30% among two years old children.

PERSPECTIVES

Definitions of allergic respiratory tract disorders in infants become more elaborate involving parental and personal history of allergy and medication; epidemiological research now attempts to identify, using biological evidence of atopy, infants at risk of persistent allergic disorders.

CONCLUSIONS

A better definition of allergic respiratory disorders in infants may help epidemiological research and early care management.

Natural history of asthma: persistence versus progression-does the beginning predict the end?

Environmental exposures during the early years and airway obstruction that develops during this time, in conjunction with genetic susceptibility, are important factors in the development of persistent asthma in childhood. Established risk factors for childhood asthma include frequent wheezing during the first 3 years, a parental history of asthma, a history of eczema, allergic rhinitis, wheezing apart from colds, and peripheral blood eosinophilia, as well as allergic sensitization to aeroallergens and certain foods. Risk factors for the development of asthma in adulthood remain ill defined. Moreover, reasons for variability in the clinical course of asthma--persistence in some individuals and progression in others--remain an enigma. The distinction between disease persistence and disease progression suggests that these are different entities or phenotypes. There is currently no consensus on whether disease progression requires either airway inflammation or airway remodeling or the combination of the two. For patients with irreversible airway obstruction, inflammation might, in part, be necessary but perhaps not entirely sufficient to induce the irreversible component, some of which could be attributed to alterations in the structure of the bronchial wall. Intervening with intermittent or daily inhaled corticosteroids in high-risk infants and children does not prevent disease progression or impaired lung growth. These findings, however, might not apply to adults, and further study in adults is needed to determine the effect of inhaled corticosteroid therapy on disease progression.

Detection of horse allergen around a stable

BACKGROUND

Integrating horse stables with built-up areas may lead to conflicts. Dispersion of horse allergen may become a health risk for allergic people. The aim was to measure the dispersion of horse allergen around a stable, considering wind speed and direction and vegetation. The disturbance of staff at a workplace nearby a stable was investigated.

METHODS

Air sampling was performed around a stable (32 horses) at distances of 50-500 m in all directions. Sampling was done with a pump and an IOM sampler. Samples were collected at 50 points during all seasons. Horse allergen levels were determined using ELISA. Disturbance by horses was studied with a questionnaire handed to the employees in an office near the stable.

RESULTS

The median horse allergen level at the stable entrance was 316 U/m(3), in the horse fields 40 U/m(3) and in the whole source area 16 U/m(3), which declined to <2 U/m(3) at about 50 m from the source area. Downwind of the prevailing winds low levels of horse allergen (2-4 U/m(3)) could sometimes be detected at up to 500 m. The staff, including those allergic to horses, managed to tolerate horses close to the workplace.

CONCLUSIONS

At low winds horse allergen spread in ambient air about 50 m from the stable and horse fields. At higher winds low allergen levels were sometimes found in open areas up to 500 m from the source area. These levels were similar to those found in the office after moving away from the stable area. The employees did not report more symptoms of allergy or asthma while working close to the stable compared to after the move.

Sublingual immunotherapy with a standardized cat dander extract: evaluation of efficacy in a double blind placebo controlled study

BACKGROUND

Little information is available on the clinical efficacy of sublingual immunotherapy (SLIT) using extracts derived from mammalian epithelia.

OBJECTIVES

To assess clinical efficacy of cat SLIT based on natural exposure challenge test (NCT).

MATERIAL AND METHODS

Fifty cat allergic patients with rhinoconjunctivitis with or without asthma were included in a randomized double blind placebo controlled clinical trial of cat SLIT during 1 year. Twenty-five patients received active treatment and 25 placebo. Sublingual immunotherapy efficacy was assessed by natural exposure challenge to a cat in a cat-room and by skin tests. Airborne Fel d 1 levels, symptom scores and peak expiratory flow (PEF) values were monitored.

RESULTS

Thirty-three (66%) out of 50 patients completed the treatment. Fel d 1 content of the maximum concentration was 0.51 microg per ml. During the build up phase, the accumulated dose was 1.7 mug of Fel d 1 and during the entire length of the study was 17.1. No adverse reports were reported. The active group showed a marked reduction (62%) in symptoms during the NCT (P < 0.001) with no changes in placebo group. Active group also showed a reduced PEF response to cat exposure (P < 0.05), and an improvement in skin test reactivity to a standardized cat extract (P < 0.05), without significant changes in placebo group. Mean Fel d 1 exposure during the NCT was 6.2 +/- 2.21 ng/m(3).

CONCLUSIONS

The results suggest that the cat SLIT used in this study was able to improve cat allergy based on natural exposure challenge.

Severity of childhood asthma and human leukocyte antigens type

We sought to learn if Class II HLA genes are associated with the severity of asthma in children. We examined a previously recruited cohort of 340 healthy children who had Class II HLA allele data available. We conducted a comprehensive review of their medical records to determine asthma status and, when present, its severity. We found that Class II HLA alleles, which were previously reported to have an association with asthma incidence, appear to have an association as well with asthma severity. These data support our hypothesis that both the incidence and severity of asthma are heritable and that HLA may play an important role in both development and severity of asthma. Because of limited statistical power, our study findings are subject to further investigation.

Interaction of maternal atopy, CTLA-4 gene polymorphism and gender on antenatal immunoglobulin E production

BACKGROUND

Genetic heritability and maternal atopy have been correlated to antenatal IgE production, but very few studies have studied gene-maternal atopy interaction on antenatal IgE production. This study investigated the interaction of CTLA-4 polymorphism with prenatal factors on the elevation of cord blood IgE (CBIgE).

METHODS

Pregnant women were antenatally recruited for collection of prenatal environmental factors by a questionnaire. Umbilical cord blood samples were collected for CBIgE detection by fluorescence-linked enzyme assay and CTLA-4 polymorphism measurement by restriction fragment length polymorphism.

RESULTS

A total of 1104 pregnant women initially participated in this cohort study, and 898 of them completed cord blood collection. 21.4% of the newborns had elevation of CBIgE (>or=0.5 kU/L). The CTLA-4+49A allele (P=0.021), maternal atopy (P<0.001) and gender (P=0.034), but not the CTLA-4+49G allele, -318C allele, -318T allele, parental smoking or paternal atopy, were significantly correlated with the CBIgE elevation in multivariate analysis. A dichotomous analysis of gene-maternal atopy interactions identified maternal atopy and CTLA-4+49A allele had an additive effect on the CBIgE elevation, especially prominent in male newborns; and in the absence of maternal atopy, CTLA-4+49GG genotype had a protective effect on CBIgE elevation in female newborns.

CONCLUSIONS

Maternal but not paternal atopy has significant impacts on CBIgE elevation depending on gender and CTLA-4+49A/G polymorphism of newborns. Control of maternal atopy and modulation of CTLA-4 expression in the prenatal stage may be a target for the early prevention of perinatal allergy sensitization.

The effect of pet ownership on the risk of allergic sensitisation and bronchial asthma

An increasing volume of evidence suggests that early contact of children with the allergens of furred pets (especially those produced by cats) may determine a lower risk of developing allergic sensitisation to these materials. A possible explanation of this data is that an early inhalation of high levels of the major cat allergen Fel d 1 induces the production of IgG and IgG4 antibodies with a "protective" effect. Other authors have shown that the prevalence of allergic sensitisation to cats, in adults, is reduced in those patients exposed to the lowest and highest levels of the allergens. On the contrary, the risk of developing sensitisation to cats is significantly higher when the patients were exposed to intermediate levels of Fel d 1. Moreover, epidemiological studies have demonstrated a relatively low prevalence of cat allergy (about 10%) in some countries where rates of cat ownership are high. This data confirms the role of indirect exposure to pet allergens in inducing allergic sensitisation. Clothes of pet owners have been indicated as the carriers for the dispersal of these allergens in pet-free environments. However, it is important to point out that exposure of highly sensitised patients to relevant amounts of pet allergens (such as in a pet shows/shops) may determine a dramatic exacerbation of nasal and/or bronchial symptoms.

Assessing respiratory function in young children: Developmental considerations

The purpose of this review is to provide practitioners and clinical investigators with an update on methods of assessing respiratory function in young children. The importance of this topic is presented in light of the natural history of asthma, as well as maturational changes that occur early in life in terms of airway development. Models of disease are cited to support the concept that injury of the mammalian airway early in postnatal life might have far-reaching consequences in terms of control of airway caliber and responsiveness. The methods currently available to measure respiratory function in our younger patients are outlined. The ability of children to perform the maneuvers necessary for this testing is considered as a function of age. Areas in which research and development are needed are highlighted.

Clinically diagnosed childhood asthma and follow-up of symptoms in a Swedish case control study

Background

Childhood asthma has risen dramatically not only in the western societies and now forms a major and still increasing public health problem. The aims of this study were to follow up at the age of ten the patterns of asthma symptoms and associations among children with a clinically diagnosed asthma in a sizeable urban-rural community and to in compare them with demographic controls using a standardised questionnaire.

Methods

In a defined region in Sweden with a population of about 150 000 inhabitants, all children (n = 2 104) born in 1990 were recorded. At the age of seven all primary care and hospital records of the 1 752 children still living in the community were examined, and a group of children (n = 191) was defined with a well-documented and medically confirmed asthma diagnosis. At the age of ten, 86 % of these cases (n = 158) and controls (n = 171) completed an ISAAC questionnaire concerning asthma history, symptoms and related conditions.

Results

Different types of asthma symptoms were highly and significantly over-represented in the cases. Reported asthma heredity was significantly higher among the cases. No significant difference in reported allergic rhinitis or eczema as a child was found between cases and controls. No significant difference concerning social factors or environmental exposure was found between case and controls. Among the control group 4.7 % of the parents reported that their child actually had asthma. These are likely to be new asthma cases between the age of seven and ten and give an estimated asthma prevalence rate at the age of ten of 15.1 % in the studied cohort.

Conclusion

A combination of medical verified asthma diagnosis through medical records and the use of self-reported symptom through the ISAAC questionnaire seem to be valid and reliable measures to follow-up childhood asthma in the local community. The asthma prevalence at the age of ten in the studied birth cohort is considerably higher than previous reports for Sweden. Both the high prevalence figure and allowing the three-year lag phase for further settling of events in the community point at the complementary roles of both hospital and primary care in the comprehensive coverage and control of childhood asthma in the community.

Analysis of clustered and interval censored data from a community-based study in asthma

Many authors in recent years have proposed extensions of familiar survival analysis methodologies to apply in dependent data settings, for example, when data are clustered or subject to repeated measures. However, these extensions have been considered largely in the context of right censored data. In this paper, we discuss a parametric frailty model for the analysis of clustered and interval censored failure time data. Details are presented for the specific case where the underlying time to event data follow a Weibull distribution. Maximum likelihood estimates will be obtained using commercially available software and the empirical efficiency of these estimators will be explored via a simulation study. We also discuss a score test to make inferences about the magnitude and significance of over-dispersion in clustered data settings. These methods will be illustrated using data from the East Boston Asthma Study.

Allergen-induced cytokine production, atopic disease, IgE, and wheeze in children

BACKGROUND

The early childhood allergen-induced immune responses associated with atopic disease and IgE production in early life are not well understood.

OBJECTIVE

We assessed the relationship of allergen-induced cytokine production by PBMCs to both atopic disease and to IgE increase in a cohort of children with a parental history of allergy or asthma (n = 112) at a median of 2 years of age. We examined cockroach (Bla g 1)-induced, house dust mite (Der f 1)-induced, and cat (Fel d 1)-induced cytokine secretion, including secretion of IFN-gamma, IL-13, IL-10, and TNF-alpha. We investigated whether distinct cytokine patterns associated with atopic disease can be detected in immune responses of children.

METHODS

PBMCs were isolated, and allergen-induced cytokine secretion was analyzed by means of ELISA. Atopic disease was defined as physician- or nurse-diagnosed eczema or hay fever. Increased IgE was defined as an IgE level of greater than 35 U/mL to dust mite, cockroach, cat, and egg white or a total IgE level of 60 U/mL or greater.

RESULTS

Compared with children without atopic disease, children with atopic disease had lower Der f 1 (P =.005) and Bla g 2 (P =.03) allergen-induced IFN-gamma levels. Compared with children without increased IgE (n = 95), those with increased IgE (n = 16) had higher Der f 1-induced (P =.006) and Fel d 1-induced (P =.005) IL-13 levels and lower Bla g 2-induced (P =.03) IFN-gamma levels. Compared with children with neither atopic disease nor repeated wheeze, children with both atopic disease and repeated wheeze had lower levels of allergen-induced IFN-gamma (P =.01 for Der f 1 and P =.02 for Bla g 2) cytokine secretion.

CONCLUSION

In young children at risk for asthma or allergy, decreased allergen-induced IFN-gamma secretion is associated with atopic disease and, in some cases, with increased IgE levels. Increased allergen-induced IL-13 secretion is most strongly associated with early life increase of IgE.

Quantification of IgE antibodies simplifies the classification of allergic diseases in 4-year-old children. A report from the prospective birth cohort study--BAMSE

Allergic diseases are common among small children, but it is still unclear how immunoglobulin E (IgE) antibodies to ambient allergens are distributed in a population-based prospective material of children at 4 years of age. The study is based on 75% (n = 4089) of all eligible children from northern Stockholm, born between 1994 and 1996 in pre-defined geographical areas. Data on exposure and outcome were obtained by parental questionnaires when the child was 3 months and 4 years of age. Of the 92% who responded to the 4 years of age questionnaire, serum was obtained in 88% of these children for analysis of IgE antibodies performed with Pharmacia CAP system (Phadiatop and food mix fx5). An antibody level > or =0.35 kUA/l was considered as positive. A positive Phadiatop or fx5 was found in 24% of the 4 years old children. A rather poor correlation was found between the two tests (r = 0.39). Occurrence of IgE antibodies > or =3.5 kU/l for both Phadiatop and fx5 in combination could predict any suspected allergic disease [asthma, rhinitis, atopic eczema dermatitis syndrome (AEDS) and allergic reaction to food] to 97.4%. However, the presence of > or =3.5 kUA/l of Phadiatop or fx5 used as single tests only, was far less efficient to predict any allergic disease. The two mixes of airborne and food allergens were also associated, not only to the severity of the allergic disease in terms of number of organ involved, but also to the severity of recurrent wheeze, in particular in boys with a positive Phadiatop who exhibited significantly limited peak flows compared to those with a negative test. Already at the age of 4, one child in four is sensitized to an allergen as assessed by Phadiatop or food mix (fx5). The presence of IgE antibodies seems not only to predict allergic diseases in this age group, but also relates to severity of such diseases, in particular to asthma. Notable, there was a poor correlation between Phadiatop and fx5 that needs to be considered when identifying allergic diseases in young children. The study demonstrates that quantification of IgE antibodies in blood may be beneficial, not only to diagnose allergic diseases in young children, but especially to serve as a marker of severity of asthma.

Treating the wheezing infant

The management of infants and small children with asthma is a challenging task because of the many issues unique to this age group that deserve special consideration. The diagnosis of asthma is limited by inherent difficulties in obtaining objective measures of lung function and airway inflammation. In persistently symptomatic patients, the decision to initiate controller therapy is not as great an issue as it is in infants and young children with recurrent episodic wheeze in whom early intervention may allow a window of opportunity potentially to alter the course of the disease. The reality is that even if atopy has been consistently implicated in the development of persistent asthma, there is not a well-established set of criteria by which patients who are likely to benefit from early intervention controller therapy can be identified. Hence, large prospective studies need to be performed evaluating the impact of early pharmacologic intervention on the natural history of infantile asthma. Many areas needing investigation involve what medications to use, how best to deliver the medications, and how to monitor the response to treatment. Only a few medications have been approved for use in this population. Long-term studies evaluating available drugs such as inhaled glucocorticoids, LABAs, and the leukotriene-modifying agents in young children still need to be performed.

Skin-prick test findings in atopic asthmatic children: a follow-up study from childhood to puberty

In a prospective cohort study we investigated the course of allergic sensitization from childhood to puberty in a group of children with atopic asthma. An attempt was made to correlate the findings with the persistence of asthma. A total of 150 children with atopic asthma established at 7 years of age were evaluated when 8-10 years of age. A battery of skin-prick tests (SPTs) to common environmental allergens, a detailed clinical history for asthma severity classification, and spirometric analyses, were performed. In 127 of these children a re-evaluation was performed at puberty. A variety of statistical methods were used to analyze the results regarding changes in skin test reactivity to individual aeroallergens and atopic index (degree of atopy), as well as to determine any correlation between these changes and the persistence of asthma in puberty. A wide spectrum of modification in skin reactivity to common environmental allergens was observed, including the complete loss of sensitization to some allergens or the development of a new one to others. Specifically, 34% of asthmatic children sensitive to Dermatophagoides pteronyssinus and 52.7% sensitive to cat lost their sensitivity in puberty, while only 7.5% and 11.1%, respectively, became sensitized (p = 0.03 and p = 0.001, respectively). In contrast, regarding pollen sensitivity, 30.2% and 24% of asthmatic children became sensitive in puberty to olive pollen and grasses mix, respectively, and only 11.7% and 12.5%, respectively, lost their sensitivity to these allergens (p = 0.04). No correlation was shown between the skin test reactivity changes to individual allergens and the persistence of asthma, but a significant correlation was found between atopic index to indoor allergens in childhood and the persistence of asthma at puberty (p = 0.04). Interestingly, multi-sensitivity to allergens (>/= 4 allergens) in childhood was also found to correlate with the persistence of asthma at puberty [p = 0.05, odds ratio (OR) = 2.65, 95% confidence interval (CI) 1.2-7.2]. Our findings indicate that significant modification of skin reactivity to common environmental allergens in atopic children with asthma in puberty can occur. However, no association between these changes and the persistence of asthma could be demonstrated, although children with indoor allergic sensitization and multi-reactivity were found to have a higher probability of maintaining their asthma in puberty.

How should a birth cohort study be organised? Experience from the German MAS cohort study

Birth cohort studies offer the opportunity to study average risks, rates and occurrence times of disease longitudinally from birth. The effect of genetic and environmental factors and their interactions can be studied. Furthermore, quantity and duration of exposure to environmental agents can be evaluated prospectively. However, prospective birth cohort studies are expensive, labour intensive and take many years to complete. Loss of subjects over time as well as recall bias complicate the interpretation of observations. This paper summarises the potential pitfalls of such studies and discusses the experience of the German Multicentre Allergy Study (MAS), which began in 1990 in five German cities and included 1314 newborns for the study of the natural course of atopic diseases.

Towards excellence in asthma management (TEAM): a populational disease-management model

Asthma management is not always optimal, and deficiencies such as inadequate treatment and insufficient patient education are often reported. Towards Excellence in Asthma Management (TEAM) is a four-phase disease management program of the Quebec Asthma Education Network (QAEN), to be carried out over a 5-year period. The program aims to achieve a continuous improvement of asthma management by caregivers and patients. The first phase, completed in January 2000, consisted of determining the actual level of asthma-associated morbidity and mortality in various Quebec regions. The second phase, which began in September 1999, included three parts: 1. Definition of the burden of asthma, taking into account the socioeconomic consequences of the disease and the quality of life of the patients, 2. Comparison of current medical practices with the Canadian Asthma Consensus Guidelines for adult and pediatric populations, 3. Evaluation of the level of compliance with medical treatment and with the environmental changes recommended to asthmatic patients. This phase is carried out via a cohort study of physicians, mainly general practitioners and pediatricians, generating a patient cohort study, in addition to substudies evaluating specific aspects of asthma care. Once the care gap is identified, it will be possible to define, apply, and evaluate a series of interventions for physicians, other health professionals, and patients. The interventions will be particularly targeted at regions where asthma incidence and morbidity are higher. We hope that this model of disease management will progressively reduce the burden associated with asthma, and potentially other chronic diseases, and will result in the more effective use of health services.

Direct on air sampling filter quantification of cat allergen

A direct on sampling filter in solution (DOSIS) method for quantification of airborne cat allergens has been developed. In this method, the allergens firmly adsorbed to a porous polytetrafluoroethylene filter are reacted with specific antibodies conjugated to alkaline phosphatase, generating a matrix-bound allergen-antibody-phosphatase complex. The treated filter is subsequently floated on a commercially available chemiluminescent phosphatase substrate solution. Aliquots of this solution are removed and analyzed luminometrically. The light intensity of the product is linearly related to the amount of allergen over a large mass range, 0-100 SQ units (1 SQ unit is about 146 pg of the allergenic protein Fel d 1). DOSIS demonstrated intra- and interassay precisions of 9% and 8% and 14% and 21% for the levels 4 and 20 SQ units per filter, respectively. The limit of quantification was estimated to 0.4 SQ units (58 pg Fel d 1) of cat allergen per filter. Application of DOSIS to analysis of cat allergen concentrations of indoor air in homes with and without cats revealed, on average, a six times higher concentration in the former (142 SQ units/m(3)) as compared to the latter (24 SQ units/m(3)). The recorded concentrations for airborne cat allergen in homes with cats are in accordance with previously reported figures. Allergen-specifically stained sampling filters revealed the particulate nature of airborne cat allergen which seemed predominantly to be carried by numerous large dust particles.

Efficacy of dry-cleaning in removing Fel d 1 allergen from wool fabric exposed to cats

BACKGROUND

The main cat allergen (Fel d 1) is ubiquitous, having been found even in indoor environments and public places where a cat has never been kept. Clothes of cat owners constitute a carrier for the distribution of Fel d 1 allergen in these environments. Schools, for example, may be a site of indirect exposure to cat allergens.

OBJECTIVE

Our goal was to investigate the efficacy of commercial dry-cleaning in removing cat allergens from wool fabrics that had been exposed to cats to evaluate a possible preventive procedure.

METHODS

Twenty-six identical wool "squares" (80 x 100 cm) were put in cat baskets for 1 week. In our laboratory, the squares were cut in half (40 x 50 cm), and one half was subjected to high-volume sampling for 5 minutes in a cat-free room. The other half was subjected to commercial dry-cleaning and then the high-volume sampling. Five wool squares not exposed to cats served as controls. Dust was collected from the wool squares with a high-volume air sampler. Particulate material was harvested onto glass fiber filters (AP 20 Millipore, Milan, Italy) with 25-mm diameter and 2-microm pore size. Each dust sample was assayed by affinity-purified monoclonal antibody against purified Fel d 1. The results were expressed as micrograms per filter. Statistical analysis was done by using the paired t test.

RESULTS

Before dry-cleaning, Fel d 1 allergen was detected on all cat-exposed wool squares. No appreciable cat allergen was detected on control materials. After commercial dry-cleaning, the amounts of Fel d 1 extracted from cat-exposed squares were significantly reduced (t = 14.63; P < 0.001) but not abolished. Three of the five control squares were contaminated by Fel d 1.

CONCLUSIONS

Commercial dry-cleaning effectively removes large amounts of cat allergen from wool materials exposed to cats but does not completely abolish this protein. Further, low Fel d 1 contamination may occur during this procedure.

Child care program directors' level of knowledge about asthma and factors associated with knowledge

Although asthmatic children spend a significant amount of time in child care programs, little is known about child care program directors' knowledge about asthma and what factors influence directors' level of knowledge about asthma. A telephone interview was conducted with directors of a randomly selected sample of all licensed child care centers and group day care homes in Connecticut. Directors of most child care programs were willing to admit asthmatic children to their programs, but their knowledge about asthma needs to be improved. Directors who have served for long periods of time may be a target group for additional education about asthma.

A multi-stage asthma screening procedure for elementary school children

This paper describes an asthma screening procedure developed to identify children with asthma for an intervention study. Students were classified into three categories based on questionnaire responses (previous asthma, suspected asthma, and no evidence of asthma). Those classified as suspected asthma by questionnaire underwent further testing, including spirometry and exercise challenge. Using the questionnaire alone, the measured asthma prevalence was 32%; the addition of spirometry and step testing reduced this estimate to 9.89%. The diagnosis of asthma was confirmed in 96% of children who saw the study physician. This screening procedure can identify school children with suspected undiagnosed asthma.

Does allergen immunotherapy alter the natural course of allergic disorders?

Allergy in patients with atopy is caused by clinical adverse reactions to environmental antigen, which is often associated with allergen-specific immunoglobulin (Ig)E production. Since allergy reflects an inappropriate immunological reaction, a therapeutic approach related to immunology is likely to actively alter the natural course of allergic disorders. Allergen immunotherapy, known at various times as desensitisation or hyposensitisation, is very recently defined by the World Health Organization as therapeutic vaccines for allergic diseases. At present, it has become a common clinical practice in selected patients for the treatment and prevention of the recurrence of allergic disorders caused by insect venoms and has proven to be effective in changing the course of allergic responses induced by grass and tree pollen, animal hair and dander, house dust mite and mold, as demonstrated by improvement in clinical symptoms, skin prick test and medication scores. Reported effects of allergen immunotherapy on the natural course of allergic disorders include (i) prevention of reaction following re-sting in insect venom allergy; (ii) prevention or decrease the rate of the natural progress of allergic rhinitis to asthma; and (iii) inhibition of new sensitisation in monosensitised children. Many aspects of the immune responses associated with allergic disorders, including antibody production, cytokine secretion, T cell activation and local inflammatory reactions, are found to be significantly altered during and/or after immunotherapy. Specifically, the ratio of allergen-specific IgG4 to IgG1 correlates well with positive clinical outcome caused by allergen immunotherapy in patients with pollen-allergy. Allergen immunotherapy affects the cytokine profile of allergen-specific T cells and switches T(H)2 type immune responses in patients with atopy towards T(H)0 or T(H)1 type responses. Although the changes in the absolute value of T(H)1 or T(H)2 cytokines appear quite variable, the increase in the ratio of T(H)1/T(H)2 cytokines is very consistent among published reports, especially in the late stage of treatment. Accumulating evidence indicates that appropriate immunotherapy prevents the onset of new sensitisation and prevents the progress of allergic rhinitis to asthma. Although the changes in B cell and T cell responses, especially IgG antibodies and T(H)1/T(H)2 cytokine production, may be the major mechanism underlying the clinical efficacy of allergen immunotherapy and the prevention of the development of allergic phenotypic changes, multiple mechanisms may be involved in the outcome of alteration of the natural course of allergic disorders.

The association between respiratory viruses and symptoms in 2-week-old infants at high risk for asthma and allergy

OBJECTIVES

The role of viral respiratory tract infections in the onset of childhood asthma and allergy is controversial, partly because of limited understanding about postnatal viral exposures. We investigated the prevalence of 3 common respiratory viruses and associated respiratory symptoms in 2-week-old infants at high risk for having asthma and allergy.

STUDY DESIGN

Frozen nasal specimens from 2-week-old children at high risk (n = 495) underwent reverse transcription-polymerase chain reaction (RT-PCR) for picornavirus-, parainfluenza-, and respiratory syncytial virus-specific nucleic acid. RT-PCR findings were related to respiratory symptoms (cold, cough, and wheeze) and to characteristics implicated with increased risk for asthma and allergy.

RESULTS

Viral RT-PCR was positive in 199 (40.2%) of 495 specimens examined, with picornavirus and parainfluenza significantly associated with respiratory symptoms. Viral prevalence was significantly higher in children born during the winter and summer months.

CONCLUSIONS

A high percentage (40.2%) of infants at high risk for asthma and allergy had been exposed to common respiratory viruses at 2 weeks of age. RT-PCR is a powerful diagnostic method that can be used in epidemiologic studies examining the role of viral respiratory tract infections in the pathogenesis of pediatric asthma and allergy.

Definition of respiratory symptoms and disease in early childhood in large prospective birth cohort studies that predict the development of asthma

We have reviewed the prospective value of early respiratory symptoms for determining the risk of development of asthma later in life by using data from studies based on the general population, hospital population, and general practices. Although "wheezing" in infancy generally has a good prognosis, it is an important risk factor for the development of asthma later in life. The prognostic value of "coughing" and "shortness of breath" in infancy for the later development of asthma is less clear. Despite the fact that no internationally accepted criteria for the definition of asthma in early childhood are available, many studies have been performed on this topic. We also investigated the outcome variables that were used to describe respiratory symptoms and disease in early childhood in the publications of nine large prospective birth cohort studies on the development of asthma. From seven of these studies, we reviewed the original questionnaires. We found that various studies used different outcome variables, but the data actually collected were similar. This is an important observation because it implies that comparisons between studies can be markedly improved by data sharing among investigators.

Residential exposures associated with asthma in US children

OBJECTIVE

Residential exposures are recognized risk factors for childhood asthma, but the relative contribution of specific risk factors and the overall contribution of housing to asthma in US children is unknown. The objective of this study was to identify risk factors and estimate the population attributable risk of residential exposures for doctor-diagnosed asthma for US children.

METHODS

A cross-sectional survey was conducted from 1988 to 1994. Survey participants were 8257 children who were <6 years old and who participated in the Third National Health and Nutrition Examination Survey, a survey of the health and nutritional status of children and adults in the United States. The main outcome measure was doctor-diagnosed asthma, as reported by the parent.

RESULTS

Six percent of children had doctor-diagnosed asthma. The prevalence of asthma was higher among boys (6.7%) than girls (5.1%) and was higher among black children (8.9%) than white children (5.2%). Risk factors for doctor-diagnosed asthma included a family history of atopy (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.5, 3.1), child's history of allergy to a pet (OR: 24.2; 95% CI: 8.4, 69.5), exposure to environmental tobacco smoke (OR: 1.8; 95% CI: 1.2-2.6), use of a gas stove or oven for heat (OR: 1.8; 95% CI: 1.02-3.2), and presence of a dog in the household (OR: 1.6; 95% CI: 1.1, 2.3). The population attributable risk of >/=1 residential exposure for doctor-diagnosed asthma in US children <6 years old was 39.2%, or an estimated 533 000 excess cases, whereas having a family history of atopy accounted for 300 000. The attributable cost of asthma as a result of residential exposures for children <6 years old was $402 million (95% CI: $296-$507 million) annually.

CONCLUSIONS

The elimination of identified residential risk factors, if causally associated with asthma, would result in a 39% decline in doctor-diagnosed asthma among US children <6 years old.

Nasal lavage biomarkers: effects of water damage and microbial growth in an office building

Selected nasal symptoms were studied in personnel who worked in a damp office building that had microbial growth (including Stachybotrys sp.) in mineral fiber insulation and gypsum board. There were also signs of dampness in the floor. Clinical examinations included nasal lavage and peak expiratory flow measurements in 12 subjects in the damp building; an additional 8 subjects in a control building (i.e., no signs of dampness or microbial growth) were also examined. Hygienic air measurements of microorganisms and volatile organic compounds were performed in both buildings. The concentrations of eosinophil cationic protein, myeloperoxidase, and albumin, and the number of subjects with eosinophils in lavage fluid, were higher among office workers in the damp building than among controls. The damp biiilding had greater amounts of total molds and bacteria in its construction than the building materials in nondamp buildings. In addition, an increase of 2-ethyl-1-hexanol in the indoor air was detected in the damp building-a sign of dampness-related alkaline degradation of diethyl-hexyl phthalate in polyvinyl chloride floor coatings. In conclusion, the results of this study indicate that exposures in a damp office building may cause an inflammatory nasal mucosal response. The results also support conclusions of earlier studies, indicating that building dampness is related to respiratory inflammation.

A new method for collecting airborne allergens

BACKGROUND

Measurement of airborne allergens has hitherto been done with the use of fixed-location pumps or personal air samplers. Our objective was to find out whether ionizers could be good tools for collecting airborne allergens. As a model we have used cat allergen (Fel d l). We have compared Fel d l levels collected by the ionizer at different time periods, as well as comparing Fel d l levels obtained with the ionizer with those of low- and high-volume pumps.

METHODS

Dust samples from floors and air samples collected with ionizers and pumps, obtained in 31 homes with cat, 23 homes without cats, and 28 day-care centres, were analysed for cat allergen content (Fel d I) by ELISA.

RESULTS

Fel d l was present in the reservoir in all homes with cats, ranging from 660 to 375,000 ng/g (GM 75,000) and in the air collected by the ionizer from 2.0 to 204 ng/24 h (GM 19.3). The allergen in homes without cat varied from < 55 to 1,800 ng/g (GM 166). Corresponding levels in air were found in two of these homes (2.3 and 7.3 ng/24 h). There was a correlation between the number of cats and the amount of airborne cat allergen (r: 0.47; P < 0.05). The levels in day-care centres were < 55 to 3,070 ng/g in dust (GM 360) and < 1.1 to 7.9 ng/24 h in the air (GM 1.6). We obtained a moderately strong correlation between air and dust samples in homes with cats (rs: 0.64; P< 0.001) and in day-care centres (rs: 0.49; P<0.05). We found that a collection period of 24 h is preferable for the ionizer. The intrahome reliability coefficient was nearly two times higher for the ionizer (r: 0.69) than the pump (r: 0.39).

CONCLUSIONS

The ionizer seems to be a good tool for monitoring the environment. It is easy to use and silent and does not disturb the airflow in the room.