International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods

Agreement between parental and self-completed questionnaires about asthma in teenagers

In studies of asthma in children, a common method is for the parents to complete questionnaires about their child's asthma symptoms. With longitudinal studies of asthma, children reach an age when they can complete the questionnaire themselves. The aim of this paper was to compare the prevalence of asthma symptoms as well as the agreement between responses to an asthma questionnaire completed by teenagers and their parents. As a part of the Obstructive Lung Disease in Northern Sweden Study (OLIN) pediatric study, where 3345, 13-14-yr-old children completed an asthma questionnaire, 294 (84%) randomly selected parents also completed the questionnaire, which included the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. There were no significant differences in the prevalence of wheeze in the last 12 months, ever asthma, or physician diagnosed asthma as reported by the parents compared with the teenagers. However, the teenagers reported a significantly higher prevalence of wheeze during or after exercise. The absolute agreement was generally very high while the level of agreement (kappa-value) was slightly lower. The highest results in both absolute agreement and kappa-value, were reached by the questions on diagnosis of asthma (98.9% and 0.93), use of asthma medicines (95.5% and 0.78), and whether the child ever had had asthma (97.2% and 0.86), respectively. In conclusion, the agreement between the parents' and the teenagers' responses to the asthma questionnaire was good. The change in methodology from parental to self-completion of the questionnaire did not affect the results in the study.

Secondhand smoke, dietary fruit intake, road traffic exposures, and the prevalence of asthma: a cross-sectional study in young children

The authors have investigated the independent effects of exposure to secondhand smoke, road vehicle traffic, and dietary fruit intake in a cross-sectional study of asthma in young children. They surveyed all children aged 4-6 years in 235 schools in the East Midlands and East of England regions of the United Kingdom in 2003. Data on respiratory symptoms, diagnoses and treatment, smoking in the home, and dietary fruit intake were collected by parental questionnaire. A geographic information system was used to map postcodes and determine the distance of the home from the nearest main road. Responses were obtained from 11,562 children. Wheeze in the past year and physician-diagnosed asthma were reported by 14.1% and 18.2%, respectively. Both of these outcomes were more common in children who lived with a smoker, and the prevalence of asthma increased with the number of smokers in the home. Asthma prevalence was not associated with proximity of the home to a main road or with dietary fruit intake. The authors conclude that, of the potential risk factors considered in this study, preventing secondhand smoke exposure may be the most effective way of preventing asthma.

Food hypersensitivity in patients with seasonal rhinitis in Ankara

BACKGROUND

Food hypersensitivity (FH) affects 1-2 % of the adult population and is more common in atopic individuals. The aim of this study was to determine the frequency of FH and risk factors for its development in patients with seasonal rhinitis (SR) in our allergy clinic.

METHODS

We performed a retrospective study based on the medical records of 774 patients out of 955 patients diagnosed with SR in an adult allergy clinic between 1 January 1991 and 31 December 2003.

RESULTS

The mean age of the patients was 29.1 +/- 9.29 and 62.7 % were females. The most common major complaints were due to nasal symptoms in 82.3 %. The mean duration of SR was 6.8 +/- 6.8 years. Patients were symptomatic for a mean of 3.5 +/- 1.7 months per year. Skin prick tests (SPT) with common aeroallergens were positive in 685 patients (90.3 %), and the most common sensitivity was against timothy (85.1 %). The most common accompanying allergic disease was FH in 14 %. FH according to history and the results of SPT performed with food allergens were discordant. The most common clinical manifestations of FH were oral allergy (49.1 %) and cutaneous symptoms (38.9 %). Risk factors for the development of FH in patients with SR were dermatological symptoms, rhinitis duration > 5 years, symptom duration > 3 months per year, SPT reactivity to Artemisia vulgaris, tree pollen allergens (Corylus avellena, Betula verrucosa), and bee allergy.

CONCLUSION

FH was the most common (14 %) accompanying allergic disease in patients with SR. SPT with food allergens have limited diagnostic value for food allergy and/or intolerance. Risk factors for developing FH in patients with SR in Turkey were dermatological symptoms, duration of rhinitis > 5 years, duration of rhinitis symptoms > 3 months per year, and SPT reactivity to Corylus avellena.

Prevalence of asthma in a Portuguese countryside town: repercussions on absenteeism and self-concept

BACKGROUND

Childhood asthma represents an increasing health problem and is the leading cause of hospital admission and absenteeism in children with chronic disease. It also compromises quality of life, eventually contributing to disturbances in self-concept. Self-concept is a recent and global perspective of "the self" and relates to skills, self-image and self-esteem. Little information is available on this topic and there are no data from Portuguese countryside towns.

OBJECTIVE

The aim of this study was to determine the prevalence of asthma among all school children in the 5th and 6th grades in a Portuguese countryside town and to establish its possible correlation with absenteeism and self-concept.

METHODS

In April 2002, two questionnaires were administered in the presence of the researcher to a group of 950 children attending different schools. The children completed the internationally renowned questionnaires: ISAAC and the Self-Concept Scale by Susan Harter.

RESULTS

Our sample (n = 818) had a mean age of 11 years (10-15 years) and a male-to-female ratio of 1/1. The cumulative prevalence of asthma was 11.9 % and that of active asthma was 8.8 %; 63.9 % of asthmatics were male and 36.1 % were female. The mean age of asthmatics was 11.34 years and 74 % had active symptoms. Comparison of this group of 97 asthmatic children with the remaining children revealed a statistically significant correlation between the presence of asthma and school absenteeism (global: p = 0.04; gymnastics: 0.05). Regarding the Self-Concept Scale a statistically significant association was found between the presence of asthma and school achievement (p = 0.027), physical appearance (p = 0.015), behavior (p < 0.000) and self-esteem (p < 0.000). No statistically significant correlations were found in social acceptance (p = 0.289) or athletic competence (p = 0.085). Asthmatic boys had higher self-concept scores than girls, except in the domain of behavior.

CONCLUSIONS

Twelve percent of the population studied was asthmatic. In asthmatic children, absenteeism was higher and self-concept was lower for almost all domains, except social acceptance and athletic achievement, probably due to overprotection.

The burden of asthma in children: an Australian perspective

The burden of asthma among children is high in Australia compared with many other countries. Recent data show that 14-16% of children report a diagnosis of asthma that remains a problem. Boys, children under the age of 5 years and urban indigenous children experience a greater burden of asthma than other children. More than one-third of children with asthma have sleep disturbance due to the illness and 60% have missed school and/or experienced other restrictions in their activities due to the disease. Despite this, there is continuing evidence of under-utilisation of effective treatment for the disease. Asthma is a major cause of healthcare utilisation among children. Since the early 1990s, there has been a decline in both hospitalisation rates and general practitioner consultation rates for asthma among children. It remains to be seen whether this favourable trend will continue and extend into the adult age range.

Prevalence of allergy-related symptoms in Singaporean children in the second year of life

This study describes the cross-sectional prevalence of symptoms associated with eczema (chronic itchy rash), asthma (wheeze), and allergic rhinitis (rhinoconjunctivitis) in 1026 subjects between 18.5 and 23 months old (median age is 21 months) in Singapore. The first 2 yr cumulative prevalence of chronic itchy rash, wheeze, and rhinoconjunctivitis were 22.1% (n=227), 22.9% (n=235), and 8.4% (n=86) respectively. In total, 42.2% (414 of 979) reported ever having any of these symptoms. Eczema, although prevalent, was diagnosed only in 34.4% (n=78) of children with chronic itchy rash. Children with this eczematous rash were also more prone to wheeze (cOR=2.0, 95% CI: 1.2-3.0) and rhinoconjunctivitis (cOR=2.0, 95% CI: 1.4-2.8). Similarly, subjects who reported rhinoconjunctivitis and chronic itchy rash were 2.4 times (95% CI: 1.6-3.6) and 1.4 times (95% CI: 1.0-2.0) more at risk of wheezing respectively. Family history of allergy was a significant risk factor for chronic itchy rash (aOR=1.8, 95% CI: 1.3-2.4) and wheeze (aOR=1.7, 95% CI: 1.3-2.4). Thus, symptoms related to allergy were already prevalent during the second year of life. Significant proportions of these symptoms are likely to be due to true atopy as strong relationship with familial history and comorbidity with other potential allergic symptoms were observed.

Is rhinitis alone or associated with atopic eczema a risk factor for severe asthma in children?

The objective of this study was to evaluate the role of rhinitis (R) and atopic eczema (E) on asthma severity among asthmatic (A) schoolchildren identified by the International Study of Asthma and Allergies in Childhood written questionnaire (WQ). WQ was applied to parents of 6-7-yr-old schoolchildren (SC, n=3033), and to adolescents (AD, 13-14 yr old, n=3487), living in Sao Paulo, Brazil. An affirmative response to 'has your child/have you had wheezing/whistling in the last year' identified those with A, and an affirmative response to 'the last 12 months has your child/have you had sneezing/runny/blocked nose when he/she you did not have a cold/flu?' identified those with R. Subjects with an affirmative response to 'has your child/have you had this itchy rash at any time in the past 12 months?' were identified as having E. Subjects who had R associated with A were identified as AR and those with A associated with R and E as ARE. A who had at least two affirmative responses to questions for asthma severity: speech disturbance, more than four acute attacks, sleep disturbance, and wheezing with exercise were defined as having severe asthma. 22.1% AD and 24.3% SC were identified as A; 47.1% of those AD and 42.0% SC had AR and 10.0% of those AD and 12.8% of SC had ARE. Considering ARE, AR and A groups, speech disturbance during an acute episode of asthma was significantly higher among ARE AD (20.0% vs. 11.5% vs. 8.7%, p<0.05), and ARE SC (22.1% vs. 13.9% vs. 10.5%, p<0.05) in comparison with A. Likewise, more than four acute attacks in the last year was significantly higher among ARE AD (24.0% vs. 14.0% vs. 10.5%, p<0.05) and ARE SC (32.6% vs. 19.4% vs. 12.8%, p<0.05) as the frequency of sleep disturbance due to wheezing, for AD (61.3% vs. 42.0% vs. 38.4%, p<0.05) and SC (77.9% vs. 67.3% vs. 58.4%, p<0.001) and for 'wheezing associated with exercise' for AD (72.0% vs. 47.5% vs. 39.9%, p<0.001) and SC (36.8% vs. 31.4% vs. 14.1%, p<0.001). Prevalence of severe asthma was higher among ARE AD (57.3% vs. 31.9% vs. 27.0%, p<0.05) and ARE SC (52.6% vs. 36.9% vs. 22.5%). In patients with A, the presence of R or E are risk factors for severe asthma, and both together (R and E) are a higher risk.

Changing prevalence of asthma in Taiwanese adolescents: two surveys 6 years apart

This study compared the prevalence of asthma among Taiwanese adolescents with individual-level risk factors and municipal-level air pollution and meteorology data to determine whether changes in these factors could explain the observed change in prevalence. We conducted two national surveys of respiratory illness and symptoms in Taiwanese middle-school students in 1995-96 and 2001. The effects of personal and environmental factors were assessed and temporal changes of outdoor monitoring data were also compared with asthma prevalence difference. A total of 44,104 children from the 1995-96 survey and 11,048 children from the 2001 survey attended schools located within 1 km of 22 monitoring stations. Lifetime prevalences of physician-diagnosed and questionnaire-determined asthma increased during this period. After adjustment for potential risk factors, the prevalence differences were statistically unchanged. Although parental education level contributed most, changes in investigated personal and environmental factors might not explain the observed changes in asthma prevalence. Municipalities with higher temperature increase were significantly associated with prevalence difference in questionnaire-determined asthma. We concluded that correlates of the investigated individual-level factors, which have changed over time, still underlie changes in asthma prevalence. Increasing temperature might be the main reason for the rising trends of asthma in Taiwanese adolescents.

Risk factors for atopic eczema in school children

OBJECTIVES: to study risk factors related to atopic eczema (AE) in school children of São Paulo. METHODS: 1972 parents or guardians of 6-7 years old children in the Southern Central area of São Paulo answered to a written questionnaire (standardized questionnaire of the International Study of Asthma and Allergies in Childhood plus a complementary questionnaire regarding family history of asthma and allergies, and exposure to environmental allergens). AE was defined by the presence of an itchy rash in the last year. Risk factors were analyzed through logical regression. RESULTS: the following factors were significantly associated with AE: history of maternal (OR: 4.1; 95%CI: 2.4 to 7.1) and paternal eczema (OR: 2.6; 95%CI: 1.4 to 5.0), dust in the child's bedroom (OR: 1.6; 95%CI: 1.1 to 2.4), lower maternal education (OR: 1.7; 95%CI: 1.1 to 2.7), rhinitis fever (OR: 1.7; 95%CI: 1.1 to 2.9) and wheezing in the last year (OR: 1.9; 95%CI: 1.2 to 2.8). CONCLUSIONS: our data suggest that AE has a specific pattern of inheritance. The presence of dust in the child's bedroom was the single environmental risk factor found. Diagnose of other allergic diseases, as well as the presence of recent symptoms were strongly associated with AE in children.

Childhood infections and risk of wheezing and allergic sensitisation at age 7-8 years

BACKGROUND

Childhood atopic disease has been associated with exposure to infections early in life. There is however considerable controversy on this issue, since evidence exists for both protective and adverse effects of infections. Aim of this study was to investigate the association between childhood infections and the occurrence of wheeze and allergic sensitisation in 7-8-year-old Dutch and German children.

METHODS

A nested case-control study was conducted among German and Dutch children participating in a large longitudinal study on respiratory health. Parents of 510 7-8-year-old children with respiratory complaints and an equal number of children without respiratory complaints were asked to complete a questionnaire. Blood samples were collected for specific serum Immunoglobulin E (IgE) analysis. Data on childhood infections were collected through records of the participating Municipal Health Services.

RESULTS

No association was found between recent wheeze and any of the childhood infections investigated. For scarlet fever infection an increased risk of allergic sensitisation (OR: 2.82; 95% CI: 1.40-5.72) and sensitisation against grasses (OR: 3.00; 95% CI: 1.35-6.69) at the age of 7-8 years was found. Varicella infection tended towards increased risk of sensitisation against grasses (OR: 1.88; 95% CI: 0.99-3.58). For allergic sensitisation and sensitisation against grasses the odds ratios increased with increasing number of infections.

CONCLUSIONS

The results do not lend support to the suggestion that childhood infection protects against wheezing or allergic sensitisation at age 7-8 years. Scarlet fever or varicella infection presented an increased risk of allergic sensitisation.

Self-reported drug allergy in a general adult Portuguese population

AIM

To estimate the prevalence of self-reported drug allergy in adults.

METHODS

Cross-sectional survey of a general adult population from Porto (all of whom were living with children involved in the International Study of Asthma and Allergies in Childhood-phase three), during the year 2002, using a self-administered questionnaire.

RESULTS

The prevalence of self-reported drug allergy was 7.8% (181/2309): 4.5% to penicillins or other beta-lactams, 1.9% to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) and 1.5% to other drugs. In the group 'allergic to beta-lactams', the most frequently implicated drug was penicillin G or V (76.2%) followed by the association of amoxicillin and clavulanic acids (14.3%). In the group 'allergic to NSAIDs', acetylsalicylic acid (18.2%) and ibuprofen (18.2%) were the most frequently identified drugs, followed by nimesulide and meloxicam. Identification of the exact name of the involved drug was possible in less than one-third of the patients, more often within the NSAID group (59.5%). Women were significantly more likely to claim a drug allergy than men (10.2% vs. 5.3%). The most common manifestations were cutaneous (63.5%), followed by cardiovascular symptoms (35.9%). Most of the reactions were immediate, occurring on the first day of treatment (78.5%). Only half of the patients were submitted to drug allergy investigations. The majority (86.8%) completely avoided the suspected culprit drug thereafter.

CONCLUSIONS

The results showed that self-reported allergy to drugs is highly prevalent and poorly explored. Women seem to be more susceptible. beta-lactams and NSAIDs are the most frequently concerned drugs.

Haplotypes of G protein-coupled receptor 154 are associated with childhood allergy and asthma

RATIONALE

Allergic diseases are influenced by both genes and environment. A 70-kb haplotype block in the G protein-coupled receptor for asthma susceptibility gene (GPR154; alias GPRA) on chromosome 7p was recently identified to influence susceptibility to asthma and elevated total serum IgE levels in adults.

OBJECTIVES

To assess the impact of GPR154 on childhood allergic disease, including allergic sensitization, asthma, and rhinoconjunctivitis, in study populations with diverse environmental backgrounds.

METHODS

We studied farm children, Steiner school children, and two reference groups from five Western European countries in the cross-sectional PARSIFAL (Prevention of Allergy Risk factors for Sensitization In children related to Farming and Anthroposophic Lifestyle) study and a sample of children from the Swedish birth cohort study BAMSE. DNA samples from 3,113 PARSIFAL and 800 BAMSE children were genotyped for 7 GPR154 polymorphisms and haplotypes were inferred. The proportions of alleles and haplotypes (H1-H7) were compared in affected children with their healthy counterparts.

RESULTS

Data indicate a global association of the haplotype block to sensitization (allergen-specific serum IgE > or = 0.35 kU/L, p = 0.022), with significant haplotype-specific associations for H1, H5, and H6. Haplotypes H1 and H5 were also significantly associated with childhood allergic asthma (p = 0.045 and p = 0.023, respectively), and H5 to asthma regardless of sensitization. A broader involvement of GPR154 in allergic diseases was further supported in allergic rhinoconjunctivitis (H3: p = 0.046). The associated haplotypes could be allocated into risk (H5/H6) and nonrisk (H1/H3) groups, a pattern supported by allelic association of single nucleotide polymorphisms (SNPs) rs324384 and rs324396.

CONCLUSIONS

Our results indicate that polymorphisms and haplotypes in the haplotype block of GPR154 are associated with asthma, rhinoconjunctivitis, and sensitization in European children.

Extent of exposure to environmental tobacco smoke (ETS) and its dose-response relation to respiratory health among adults

Background

There is a dearth of standardized studies examining exposure to environmental tobacco smoke (ETS) and its relationship to respiratory health among adults in developing countries.

Methods

In 2004, the Syrian Center for Tobacco Studies (SCTS) conducted a population-based survey using stratified cluster sampling to look at issues related to environmental health of adults aged 18–65 years in Aleppo (2,500,000 inhabitants). Exposure to ETS was assessed from multiple self-reported indices combined into a composite score (maximum 22), while outcomes included both self-report (symptoms/diagnosis of asthma, bronchitis, and hay fever), and objective indices (spirometric assessment of FEV₁ and FVC). Logistic and linear regression analyses were conducted to study the relation between ETS score and studied outcomes, whereby categorical (tertiles) and continuous scores were used respectively, to evaluate the association between ETS exposure and respiratory health, and explore the dose-response relationship of the association.

Results

Of 2038 participants, 1118 were current non-smokers with breath CO levels ≤ 10 ppm (27.1% men, mean age 34.7 years) and were included in the current analysis. The vast majority of study participants were exposed to ETS, whereby only 3.6% had ETS score levels ≤ 2. In general, there was a significant dose-response pattern in the relationship of ETS score with symptoms of asthma, hay fever, and bronchitis, but not with diagnoses of these outcomes. The magnitude of the effect was in the range of twofold increases in the frequency of symptoms reported in the high exposure group compared to the low exposure group. Severity of specific respiratory problems, as indicated by frequency of symptoms and health care utilization for respiratory problems, was not associated with ETS exposure. Exposure to ETS was associated with impaired lung function, indicative of airflow limitation, among women only.

Conclusions

This study provides evidence for the alarming extent of exposure to ETS among adult non-smokers in Syria, and its dose-response relationship with respiratory symptoms of infectious and non-infectious nature. It calls for concerted efforts to increase awareness of this public health problem and to enforce regulations aimed at protecting non-smokers.

Prevalence of wheeze and self-reported asthma and asthma care in an urban and rural area of Tanzania and Cameroon

We investigated the prevalence of wheeze, self-reported asthma, and asthma care via four cross-sectional surveys among adults and children (5-15 years) in urban and rural populations from Tanzania and Cameroon. Age-standardized prevalence of current wheeze (in the previous year) was 2.2% to 5.0% in adults and 1.9% to 5.2% in children in Tanzania, and 1.3% to 2.5% (adults) and 0.8% to 5.4% (children) in Cameroon. There were no consistent patterns of urban:rural prevalence. Peak flow rates varied with age, peaking at 25-34 years, and were higher in urban areas (age adjusted difference 22-70 L/min) and in the Tanzania populations. Awareness (83%-86% versus 52%-58%) and treatment (43%-71% versus 30%-44%) of asthma was higher among those with current wheeze in rural areas. Use of inhaled drugs, particularly steroids, was rare. Diagnosis by traditional healers (15%) and use of traditional remedies (62% of those recalling any treatment) were common only among self-reported asthmatic patients in rural Cameroon. Asthma is an importantclinical condition in sub-Saharan Africa. There were major gaps in clinical care, particularly in urban areas. Sustainable methods for delivering accessible and effective asthma care in sub-Saharan Africa are required.

Association of air-conditioning with respiratory symptoms in office workers in tropical climate

To evaluate the association of heating, ventilation and air-conditioning systems (HVAC) and respiratory symptoms in a tropical city, self-administered questionnaires were given to 2000 individuals working in air-conditioned office buildings and to 500 control workers in naturally ventilated buildings. Reported symptoms from the two populations were analyzed using chi-square tests, univariate and multiple logistic regressions models. Symptoms were the outcome variable and the odds ratios were adjusted by gender, age, accumulated work time, smoking habits and atopic background. There was a 79.8% response rate and there was a positive association of nasal symptoms (odds ratio, OR = 1.59, 95% confidence interval, CI = 1.11-2.28), naso-ocular symptoms (OR = 1.58, 95% CI = 1.05-2.38), persistent cough (OR = 3.04, 95% CI = 2.00-4.63) sinusitis symptoms (OR = 1.85, 95% CI = 1.27-2.71) and building-related worsening of the symptoms (OR = 4.92, 95% CI = 2.93-8.27) with working in air-conditioned buildings. In conclusion, our study suggests that artificial air-conditioning is a matter of concern for respiratory symptoms in cities with hot and humid climate.

PRACTICAL IMPLICATIONS

This study suggests that indoor air-related respiratory symptoms are a matter of concern in places with hot and humid climate. The regression models were adjusted by confounders that could be used in further reanalysis of indoor air quality related symptoms and ventilation systems with expanded variety of climatic conditions.

Markers of eosinophilic inflammation and tissue re-modelling in children before clinically diagnosed bronchial asthma

Chronic inflammatory changes in the bronchial mucosa have been well documented in patients with established asthma. Much less is known of the changes, which occur in the airways of children early in the evolution of their disease with most of the information based on indirect markers of inflammation only. We evaluated markers of inflammation and tissue re-modelling in bronchial biopsies from children with early respiratory symptoms before a clear clinical diagnosis of bronchial asthma could be made. We examined bronchial biopsies performed in 27 children between the ages of 1.2 and 11.7 yr who were bronchoscoped for a clinical indication because of recurrent or chronic respiratory symptoms. The patients were re-evaluated 22-80 months after the original bronchoscopy to determine whether or not they had subsequently developed bronchial asthma. There were more eosinophils in the bronchial mucosa (129.4 vs. 19.1 cells/mm2 of lamina propria, p <0.001) and the thickness of the subepithelial lamina reticularis was greater (4.65 vs. 3.72 microm, p=0.044) in children with bronchial asthma diagnosed at follow-up, compared with the children who did not progress to asthma. Eosinophilic inflammation and airway re-modelling occur early in the natural history of bronchial asthma and are present even before asthma would be diagnosed based on clinical symptoms. Recognition of these changes and their significance for clinical disease should emphasize the need for timely detection and diagnosis of asthma in children to facilitate the early introduction of anti-asthma therapy.

Obesity and asthma in 11-12 year old New Zealand children in 1989 and 2000

BACKGROUND

There has been a concurrent increase in the prevalence of obesity and asthma in recent years in New Zealand and other countries.

METHODS

Two cross sectional surveys performed in 1989 and 2000 were used to test this association in children of mean age 11.7 years. Body mass index (BMI) was calculated as weight/height2 (kg/m2) and obesity and overweight defined according to an international standard. Standard questions were used to measure the prevalence of asthma symptoms.

RESULTS

Significant increases in the prevalence of reported symptoms and disease between 1989 and 2000 were not explained by a concurrent increase in the prevalence of obesity. In 2000, multivariate analysis showed that increasing BMI standard deviation score was significantly associated with current wheeze (p=0.002), inhaled steroid use (p=0.004), and the use of any medication (p=0.001). None of the associations was significantly different for boys or girls.

CONCLUSION

There is some evidence for an association of obesity with asthma symptoms and treatment but this does not explain the increasing prevalence of this disease.

Exposure to pets, and the association with hay fever, asthma, and atopic sensitization in rural children

BACKGROUND

An increasing number of studies report pet exposure to be associated with lower risk of asthma and allergies. This 'protective pet effect' has been suggested to result from a modified T-helper (Th)2-cell response, or because of increased microbial load in homes where pets are kept. We examined the associations between pet contact and the occurrence of asthma and allergies in children of the rural Allergy and Endotoxin (ALEX) population, taking farm animal contact, endotoxin and cat allergen levels in mattress dust into account.

METHODS

Information about contact with pets and farm animals, asthma and allergy were collected for 812 children by a standardized parents' questionnaire and an interview. Mattress dust endotoxin and cat allergen levels as well as specific IgE and IgG4 antibodies to Fel d1 were determined.

RESULTS

Current contact with dogs was inversely associated with diagnosed hay fever (OR 0.26, 95% CI 0.11-0.57), diagnosed asthma (OR 0.29, 95% CI 0.12-0.71), sensitization to cat allergen (OR 0.48, 95% CI 0.23-0.99) and to grass pollen (OR 0.55, 95% CI 0.33-0.94), but not with increased IgG4 levels. Early and current contact with cats were associated with reduced risk of wheezing (OR 0.48, 95% CI 0.23-1.00, and OR 0.49, 95% CI 0.26-0.92, respectively) and grass pollen sensitization. Adjustment for farm animal contact but not for endotoxin and cat allergen exposure attenuated these associations and the effect of pet was stronger among farmers' children.

CONCLUSION

Although pet exposure was very frequent in this rural population, the inverse relation between current dog contact, asthma and allergy was mostly explained by simultaneously occurring exposure to stable animals or was restricted to farm children. In addition, a subtle form of pet avoidance may contribute to the protective effect of pet.

Atypical bacterial pneumonia and asthma risk

The role of respiratory infections in asthma is poorly understood. Atypical bacteria Mycoplasma pneumoniae and Chlamydia pneumoniae are present in the lower airways of approximately 50% of asthmatics. This study tested the hypothesis that early life community-acquired pneumonia caused by Mycoplasma pneumoniae or Chlamydia pneumoniae is associated with increased asthma prevalence. Thirty-five subjects with a history of community-acquired pneumonia (22 due to atypical bacteria, 13 due to nonatypical pathogens) were evaluated by questionnaire 7-9 years after the episode of pneumonia. Subjects with a history of either typical or atypical pneumonia demonstrated increased asthma prevalence. Current or past asthma prevalence was 55% in subjects with atypical bacterial pneumonia and 61.5% in subjects with nonatypical bacterial pneumonia. Significant between-group differences were not demonstrated with regard to asthma prevalence (risk ratio=0.89; 95% confidence interval=0.49-1.61), current bronchodilator use [1.18 (0.44-3.17)], and family history of atopy [1.18 (0.73-1.91)], or asthma [1.63 (0.68-3.88)]. These data suggest that atypical bacterial pneumonia confers a risk of asthma similar to that seen with nonatypical bacterial pneumonia. Prospective studies are warranted to more fully evaluate the importance of atypical bacterial pneumonia as an asthma risk factor.

Asthma and other allergic conditions in Colombia: a study in 6 cities

BACKGROUND

No detailed information is available on the burden and impact of allergic diseases simultaneously for adults and children in Colombia and most Latin American countries.

OBJECTIVES

To investigate the prevalence of asthma, allergic rhinitis, and atopic dermatitis symptoms in 6 cities in Colombia; to measure patient expenses and school days and workdays lost; to describe disease severity; and to determine levels of total and specific IgE in asthmatic subjects.

METHODS

A multistage stratified random sample selection of schools with subjects aged 5 to 18 years in each city was used. Guardian subjects selected were contacted, and home visits were arranged. Subjects aged 1 to 4 years and older than 19 years were also selected randomly by systematic sampling based on the addresses of the subjects aged 5 to 18 years. Subjects with asthma symptoms were invited to provide a blood sample.

RESULTS

Information was obtained from 6,507 subjects. The prevalence of asthma, rhinitis, and atopic dermatitis symptoms in the past 12 months was 10.4% (95% confidence interval [CI], 9.7%-11.1%), 22.6% (95% CI, 21.6%-23.6%), and 3.9% (95% CI, 3.4%-4.4%), respectively. Thirty-eight percent of asthmatic subjects had visited the emergency department or have been hospitalized, and 50% reported lost school days and workdays. Seventy-six percent of sampled asthmatic patients were considered to be atopic.

CONCLUSIONS

The burden of disease and societal consequences of allergic entities in urban settings in countries such as Colombia are of concern but are largely ignored, perhaps because of the misconception that these diseases are of public health importance only in industrialized nations.

Cytomegalovirus infection and development of allergic diseases in early childhood: interaction with EBV infection?

BACKGROUND

Chronic replication of cytomegalovirus and EBV in early life may affect the immune system and play a role in the development of allergy in children.

OBJECTIVE

To assess the relation between cytomegalovirus infection and allergic disorders in children, including a possible interaction with EBV infection.

METHODS

From a prospective birth cohort study in Stockholm, on factors of importance for development of allergy, 2581 four-year-old children were enrolled. The classification of allergic diseases was based on questionnaire answers and determination of IgE antibodies to common airborne and food allergens. IgG to cytomegalovirus was determined by a commercial ELISA and to EBV by indirect immunofluorescence.

RESULTS

A total of 1191 (46%) children were cytomegalovirus-seropositive. There were no significant associations between seropositivity to cytomegalovirus and allergic manifestations, such as bronchial asthma, suspected allergic rhinitis, or atopic dermatitis. Seropositivity to cytomegalovirus alone, ie, without seropositivity to EBV, was related to IgE antibodies to airborne and food allergens (adjusted odds ratio, 1.8; 95% CI, 1.2-2.9). An antagonism between cytomegalovirus and EBV in relation to sensitization to airborne and food allergens was suggested ( P = .05).

CONCLUSION

The study does not support the hypothesis that previous cytomegalovirus infection plays an important role in the pathogenesis of bronchial asthma, suspected allergic rhinitis, or atopic dermatitis in children. However, in the absence of EBV infection, cytomegalovirus infection may be related to sensitization to airborne and food allergens.

[Time trends in prevalence of symptoms of allergic rhinitis in 13-14 year-old schoolchildren in 8 areas of Spain between 1993-1994 and 2001-2002 according to the International Study of Asthma and Allergies in Childhood (ISAAC)]

BACKGROUND AND OBJECTIVE

Our goal was to estimate the time trends in the prevalence of symptoms of allergic rhinitis (AR) and its geographic variations.

POPULATION AND METHOD

During 2001-2002, the phase 3 of ISAAC study was carried out, and a comparison with the phase 1 (1993-1994) was done. This cross sectional study included 30,046 schoolchildren 13-14 years-old from 9 centers (Asturias, Barcelona, Bilbao, Cartagena, Castellon, Madrid, Pamplona, Valencia, and Valladolid). A questionnaire about rhinitis symptoms self-administered to schoolchildren was used at schools and institutes with a participation rate of 100% to 75.8%.

RESULTS

A divergent time trend of AR prevalence symptoms was observed with a decrease in Barcelona and Bilbao, a stabilization in Cartagena, Pamplona, and Valencia, and an increase in Castellon; Madrid and Valladolid; however, there was an overall increase in nasal allergy. The prevalence of rhinoconjunctivitis in the past year (Prevalence Ratio [PR] = 1,13; 95% Confidence Interval [CI], 1.07-1.19) and nasal allergy ever (PR = 1.22; 95% CI, 1.15-1.30) increased after adjusting for gender, center and season change. The prevalence of rhinoconjunctivitis and nasal allergy varied according to centres, Madrid, Asturias, Cartagena and Bilbao exhibiting the higher prevalence. Taken as a whole, these data indicate a middle prevalence of AR when compared with other countries following an ISAAC methodology.

CONCLUSIONS

Two patterns of time trend of prevalence of symptoms of AR were observed. The investigation of risk factors at local level could be important in order to undertake preventive measures.

Effect of mite-impermeable mattress encasings and an educational package on the development of allergies in a multinational randomized, controlled birth-cohort study -- 24 months results of the Study of Prevention of Allergy in Children in Europe

BACKGROUND

Sensitization to house dust mite (HDM) is an important risk factor for the development of asthma and allergic disease in childhood. Higher levels of HDM allergen are linked to increased sensitization to HDM.

OBJECTIVE

To study the effect of mite-impermeable mattress encasings and an educational package on the development of allergies in a newborn cohort.

METHODS

Six hundred and ninety-six newborns at high risk of developing allergies were enrolled in three European countries (Germany, Austria, UK) in a prospective, randomized, controlled birth-cohort study. Children were randomly assigned to an intervention and control group. Intervention measures included the use of mite-impermeable mattress encasings for the child's bed and a simple educational package on allergen avoidance. The control group received basic information about allergies. Children were followed up at age 6, 12, 18 and 24 months.

RESULTS

80.9% of the children were followed up to the age of 24 months. No difference in the prevalence of sensitization to HDM (control vs. intervention group: 8.4% vs. 6.1%, P=0.33) or the development of symptoms (recurrent wheezing 10.3% vs. 10.7%, nocturnal cough 12.5% vs. 12.5%) or allergic diseases (asthma 3.5% vs. 5.1%, eczema 20.0% vs. 19.6%, rhinitis 28.9% vs. 25.8%) could be found between the control and intervention group.

CONCLUSION

In this study, HDM avoidance did not show a protective effect on the development of sensitization to HDM or symptomatic allergy in children at age 24 months.

Bronchial hyper-responsiveness to hypertonic saline and blood eosinophilic markers in 8-13-year-old schoolchildren

BACKGROUND

In adult asthma, bronchial hyper-responsiveness (BHR) to indirect stimuli reflects eosinophilic activation more closely than BHR to stimuli that directly cause smooth muscle contraction.

AIM

To assess the relationship between BHR to the indirect stimulus hypertonic saline (HS), blood eosinophil numbers, and serum eosinophilic cationic protein (ECP) in children with and without current wheeze.

METHODS

A cross-sectional survey among 8-13-year-old schoolchildren, using the International Study of Asthma and Allergic disease in Childhood questionnaire, bronchial challenge with HS, skin prick tests, serum IgE, blood eosinophil counts and ECP (in a subset). Based upon the presence of current wheeze (WHE) and BHR, we defined three case groups (WHE+BHR+, WHE-BHR+, WHE+BHR-) and the reference group (WHE-BHR-). By regression analyses, each case group was compared with the reference group for differences in atopic sensitization, blood eosinophil counts and serum ECP.

RESULTS

Complete data were obtained for 470 children. BHR was present in 103 children (22%), 66 being asymptomatic and 37 symptomatic. Children of all three case groups were more often atopic. Sensitization to indoor allergens particularly occurred in children with BHR, irrespective of symptoms (P < 0.05). Children with WHE+BHR+ had highest values for blood eosinophils and serum ECP (P < 0.05). Children with WHE-BHR+ had less severe responsiveness. In atopic children with WHE-BHR+, serum ECP was higher than in children with WHE-BHR-(P < 0.05).

CONCLUSIONS

BHR to HS is associated with blood markers of eosinophilic activation, particularly in atopic children.

Stabilization of asthma prevalence among adolescents and increase among schoolchildren (ISAAC phases I and III) in Spain

BACKGROUND

Most studies show a steep increase in asthma prevalence in the last decades, although few studies had applied the same methodology. Recent reports point out the possibility that the epidemic has come to an end. We have studied the prevalence of asthma in a very large sample of children, repeating the study eight years apart.

METHODS

Repeated cross-sectional studies using the International Study of Asthma and Allergies in Childhood (ISAAC) protocol in a sample of Spanish schoolchildren 6-7 (parent-reported) and 13-14 (self-reported) years old in 1994-95 (phase I) and 2002-2003 (phase III). The number of participants was 42 417 in phase I and 42 813 in phase III. The participation rate was over 87% (13-14 years) and 70% (6-7 years).

RESULTS

The prevalence of wheezing in the previous year in children aged 13-14 years was 9.0 and 9.3% for boys and 9.6 and 9.2% for girls for phases I and III, respectively. Children 6-7 years of age showed a substantial increase in wheezing in the previous year (7.0 and 10.7% for boys and 5.3 and 8.2% for girls). Other symptoms and severity indexes followed the same patterns.

CONCLUSIONS

In the last 8 years, the prevalence of asthma has not changed in 13-14-year-old Spanish children but has increased substantially in 6-7-year olds.

Are oral contraceptive use and pregnancy complications risk factors for atopic disorders among offspring?

In utero programming of atopic manifestations has been suggested. We investigated the association between oral contraceptive (OC) use before, and complications during pregnancy (CDP) and asthma, along with other atopic manifestations. The study is based on neonates from Kingston and St Andrew, a geographic subcohort from the Jamaican Perinatal Morbidity, Mortality Survey conducted in 1986-1987. Information on OC use and CDP was extracted from maternal interviews and medical records. In a follow up in 1997-1998, via interviews with mothers, trained nurses collected information on asthma/wheezing, coughing, eczema, and hay fever. Data, specific to this paper, from birth and 11-12 yr of age was available for a total of 1040 of the 1720 members of the geographic subcohort. Using logistic regression, controlling for confounders, we estimated adjusted odds ratio (aOR) and corresponding 95% confidence intervals (CI). For asthma or wheezing, and coughing, aOR for OC use were 1.81 (95% CI: 1.25-2.61), and 2.72 (95% CI: 1.41-5.24), respectively. CDP was only shown to be a significant risk factor for hay fever. Additionally, a higher number of older siblings were protective for hay fever. The results suggest that asthma in childhood may be programmed in utero.

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

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

Long-term pulmonary sequelae in children who were treated with extracorporeal membrane oxygenation for neonatal respiratory failure

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for neonates with intractable respiratory failure, but the long-term pulmonary outcome is unknown. Our aim was to investigate the long-term pulmonary sequelae of these children.

STUDY DESIGN

We studied 50 children at 11.1 +/- 1.1 years (mean +/- SD) who had been treated with neonatal ECMO for meconium aspiration syndrome (38%), sepsis (18%), sepsis with pneumonia (12%), congenital diaphragmatic hernia (12%), congenital heart disease (8%), persistent pulmonary hypertension of the newborn (6%), and respiratory distress syndrome (4%) and 27 healthy controls (10.8 +/- 1.6 years). All subjects completed a respiratory questionnaire and performed pulmonary function and graded cardiopulmonary exercise testing.

RESULTS

Neonatal ECMO survivors had hyperinflation (median residual volume: 131%), airway obstruction (median forced expired volume in 1 second: 79%), lower oxygen saturation with exercise, and lower peak oxygen consumption than controls. The ECMO group achieved similar exercise minute ventilation to controls, with more rapid and shallow breathing. ECMO survivors had an increased frequency of exercise-induced bronchospasm. Those who required higher inspired oxygen tension and ventilator pressures after weaning from ECMO had lower forced expired volume in 1 second and oxygen saturation values.

CONCLUSION

Neonatal ECMO survivors experience lung injury lasting into later childhood. Lung dysfunction correlates with the extent and duration of barotrauma and oxygen exposure as neonates.

Infections, medication use, and the prevalence of symptoms of asthma, rhinitis, and eczema in childhood

BACKGROUND

The "hygiene hypothesis" postulates that infections during infancy may protect against asthma and atopy. There is also some evidence that antibiotic and/or paracetamol use may increase the risk of asthma.

METHODS

The study measured the association between infections, and medication use early in life and the risk of asthma at age 6-7 years. It involved 1584 children who had been notified to public health services with serious infections at age 0-4 years, and 2539 children sampled from the general population. For both groups, postal questionnaires were completed by parents.

RESULTS

There was little difference in the prevalence of current wheezing between the childhood infections group (prevalence = 23.5%) and the general population group (prevalence = 24.3%). There was also little difference whether the major site of infection was gastrointestinal (prevalence = 24.1%), invasive (prevalence = 24.6%) or respiratory (prevalence = 21.1%). However, in both groups, there were associations with antibiotic (OR = 1.78, 95% CI 1.49 to 2.14) or paracetamol (OR = 1.38, 95% CI 1.04 to 1.83) use in the first year of life or recent paracetamol use (OR = 2.10, 95% CI 1.78 to 2.49) and current wheezing. There was a weak protective effect of childhood infections in children who had not used antibiotics in the first year of life (OR = 0.78, 95% CI 0.55 to 1.10).

CONCLUSIONS

These findings are consistent with other evidence that antibiotic use early in life may increase the risk of asthma. They are also consistent with some preliminary evidence associating paracetamol use with an increased risk of asthma. Any protective effect of notifiable childhood infections was weak.

Role of prostanoid DP receptor variants in susceptibility to asthma

BACKGROUND

Previous genetic studies have associated the region of the human genome (14q22.1) containing the gene for the prostanoid DP receptor (PTGDR) with asthma. A study of a mouse model suggests that the receptor is required for the expression of the asthma phenotype. Our associations of asthma with functional genetic variants of PTGDR link these observations.

METHODS

We identified and evaluated combinations of genetic variants that influence PTGDR transcription for disease association in case-control studies of 518 white patients with asthma and 175 white controls and 80 black patients with asthma and 45 black controls.

RESULTS

We identified four novel and two previously reported single-nucleotide polymorphisms (SNPs) in PTGDR and its vicinity. These define four common three-SNP haplotypes, which vary in their ability to support transcription of PTGDR and have distinct DNA-binding-protein affinity profiles. Individual PTGDR SNPs were significantly associated with asthma in both populations. Specific PTGDR haplotypes were significantly associated with a diagnosis of asthma in a large case-control study of whites (P=0.002); we confirmed these findings in a second population of blacks (P=0.01). Multivariate analysis of the haplotype combinations (diplotypes) demonstrated that both whites (odds ratio, 0.55; 95 percent confidence interval, 0.38 to 0.80; P=0.002) and blacks (odds ratio, 0.32; 95 percent confidence interval, 0.12 to 0.89; P=0.03) who had at least one copy of the haplotype with a low transcriptional efficiency had a lower risk of asthma than subjects with no copies of the haplotype.

CONCLUSIONS

Our functional and genetic findings identify PTGDR as an asthma-susceptibility gene.

Road-traffic pollution and asthma - using modelled exposure assessment for routine public health surveillance

Asthma is a common disease and appears to be increasing in prevalence. There is evidence linking air pollution, including that from road-traffic, with asthma. Road traffic is also on the increase. Routine surveillance of the impact of road-traffic pollution on asthma, and other diseases, would be useful in informing local and national government policy in terms of managing the environmental health risk.

Several methods for exposure assessment have been used in studies examining the association between asthma and road traffic pollution. These include comparing asthma prevalence in areas designated as high and low pollution areas, using distance from main roads as a proxy for exposure to road traffic pollution, using traffic counts to estimate exposure, using vehicular miles travelled and using modelling techniques. Although there are limitations to all these methods, the modelling approach has the advantage of incorporating several variables and may be used for prospective health impact assessment.

The modelling approach is already in routine use in the United Kingdom in support of the government's strategy for air quality management. Combining information from such models with routinely collected health data would form the basis of a routine public health surveillance system. Such a system would facilitate prospective health impact assessment, enabling policy decisions concerned with road-traffic to be made with knowledge of the potential implications. It would also allow systematic monitoring of the health impacts when the policy decisions and plans have been implemented.

Influence of MMR-vaccinations and diseases on atopic sensitization and allergic symptoms in Swiss schoolchildren

The prevalence of asthma and allergic disease has increased in many countries. It has been proposed that vaccinations may contribute to the development of allergic disease by reducing clinical infections in infancy or through the direct IgE-inducing effects of the vaccines. Evidence for a potential role of immunizations in the development of allergic disease is scarce. Therefore the objective was to study the associations between vaccinations against measles, mumps and rubella (MMR), natural infections of these diseases and atopic sensitization to indoor and outdoor allergens and allergic symptoms in schoolchildren. The cross-sectional study including 1537 8(th) grade school children aged 13-15 years living in 10 communities across Switzerland was organized in the framework of an environmental health surveillance program within the School Health Services (Swiss Surveillance Program of Childhood Asthma and Allergies with respect to Air Pollution and Climate, SCARPOL). Main outcome measures were asthma and sneezing during pollen season assessed by parental questionnaires and atopic sensitization determined by IgE concentrations to various allergens. It was found that parents' reported history of measles or mumps was associated with a stronger immune response than two or more vaccinations against the respective infection (measles: geometric mean IgG titers (GMT) lU/ml (95% Cl) 2.8 (2.0-3.9) vs. 1.2 (1.0-1.4), mumps: GMT PE/ml (95% Cl) 16.3 (13.9-19.1) vs. 8.5 (6.1-11.7). With respect to atopic sensitization similar associations for exposure by natural MMR-infections or MMR-vaccinations were found: measles: OR (95% Cl) 1.02 (0.53-1.96) vs. 1.22 (0.69-2.16), mumps: 0.59 (0.38-0.93) vs. 0.79 (0.49-1.27), rubella: 0.93 (0.61-1.43) vs. 0.95 (0.66-1.37), respectively. Inverse relationships were found between the risk of asthma and a positive disease history or vaccination of measles 0.36 (0.14-0.91) vs. 0.45 (0.21-0.98) or a positive serum titer against measles 0.65 (0.35-1.20). From the present study can be concluded that exposure by MMR-vaccinations or natural MMR-infections in childhood does not increase the risk of sensitization to common allergens as well as to allergic respiratory diseases. MMR-vaccinations or natural MMR-infections are therefore an unlikely factor contributing to the increase in atopic disease in developed countries.

Infant immunization and the occurrence of atopic disease in Dutch and German children: a nested case-control study

Our goal was to assess the role of early childhood vaccination in the occurrence of respiratory symptoms and allergic sensitization in 7-8-year-old Dutch and German children. A nested case-control study was conducted among children participating in a large longitudinal study on respiratory health, to study the relationship between vaccination (bacille Calmette-Guérin (BCG), pertussis, measles/mumps, rubella, and Haemophilus influenza type b (Hib)) and respiratory symptoms and allergic sensitization. Parents of 510 7-8-year-old children with respiratory complaints and an equal number of randomly selected children without respiratory complaints were asked to complete a questionnaire. Blood samples were collected for specific serum IgE analysis. Vaccination status was assessed through the records of the participating Municipal Health Services. No association between vaccination against pertussis, measles, rubella, or Hib and respiratory symptoms or allergic sensitization was found. For sensitization against house dust mite, BCG vaccination resulted in an increased risk (OR, 2.28; 95% CI, 1.05-4.96). Birth order was inversely associated with allergic sensitization, but was not related to respiratory symptoms. We found an association between BCG vaccination and the subsequent risk for sensitization against house dust mite. No evidence was found for an association between vaccination and respiratory symptoms. Earlier reports of an association of birth order with atopic disease were supported by the results of the present study.

Quality of life in young urban children: does asthma make a difference?

The purpose of this study was to determine whether asthma status and severity have an impact on the quality of life of urban elementary school children. Participants were 1292 caregiver-child dyads from six schools serving low-income, ethnic minority, urban families; 53% of the children were female. Caregivers provided data on the children's asthma diagnosis and frequency in the last 12 months of asthma symptoms, use of medication for asthma, emergency room visits, and hospitalizations. Using the KINDL, a generic quality of life instrument, children reported on their health-related quality of life (HRQL). Results revealed a high prevalence of current asthma (18%). No differences were found in HRQL based on having current asthma or the severity of asthma as assessed by proxy measures of health care utilization and limited functioning. These findings are consistent with previous research indicating that HRQL is influenced by several factors other than asthma status and severity. The implications of these results for intervention are discussed.

Risk factors and prevalence of asthma or atopic dermatitis in young children by a questionnaire survey

Little is known about the relation between atopic disorders and altitude of residence. The author investigated the prevalence of asthma and atopic dermatitis, and their relationship with altitude of residence. A total of 24,631 children aged four years and under in Gunma Prefecture, Japan, were surveyed. The ATS-DLD questionnaire for asthma was distributed together with an item on atopic dermatitis. Some confounding variables were also asked. The author judged subjects as having asthma when positive answers were given to all 6 items in the ATS/DLD questionnaire. The prevalence of asthma in subjects with atopic dermatitis was higher than in those without (5.1% vs. 1.8%). Logistic regression analyses for asthma and atopic dermatitis were conducted, and male sex, increasing age, family history of target disease, and living at higher altitude commonly and significantly contributed to an increase in the risk of each allergic disorder. For asthma, not being the eldest child, and past or present history of atopic dermatitis were also selected as risk factors. There was an increase in the prevalence of atopic disorders in groups living at a higher altitude was observed in this area.

Atmospheric pollution and the prevalence of asthma: study among schoolchildren of 2 areas in Rio de Janeiro, Brazil

BACKGROUND

Air pollutants have been associated with the exacerbation of respiratory diseases. They may intensify the inflammatory allergic response and airways reactivity to inhaled allergens. However, it is still not clear if air pollution contributes to the increased prevalence of asthma.

OBJECTIVE

To investigate if different levels of air pollution exposure can be related to differences in the prevalence of asthma.

METHODS

The International Study of Asthma and Allergies in Childhood (ISAAC) protocol was used to determine and compare the prevalence of asthma among schoolchildren in 2 cities of the metropolitan region of Rio de Janeiro, Brazil, Duque de Caxias (DC) and Seropédica (SR), which have different levels of atmospheric pollution. The research involved 4,064 students aged 13 to 14 years from 49 schools in DC and 1,129 from 17 schools in SR. Air pollution was evaluated by the concentration of inhalable particulate matter (PM10).

RESULTS

ISAAC's written questionnaire was answered by 4,040 students aged 13 to 14 years in DC and 1,080 in SR. Between 1998 and 2000, the PM10 annual arithmetic mean was 124 microg/m3 in DC and 35 microg/m3 in SR (acceptable level is up to 50 microg/m3). The prevalence of wheezing ever was 35.1% in DC and 29.9% in SR (P = .001), and the prevalence of wheezing in the last 12 months was 19.0% in DC and 15.0% in SR (P = .002). In DC, 14.5% of the adolescents presented 1 to 3 crises of wheezing in the last year, whereas in SR only 11.0% presented 1 to 3 crises (P = .003).

CONCLUSIONS

In this study, the prevalence of asthma in adolescents was directly related to atmospheric pollution.

Lower prevalence of reported asthma in adolescents with symptoms of rhinitis that received neonatal BCG

BACKGROUND

BCG is a vaccine used against tuberculosis and leprosy and is an immunostimulant that primes T(H)1 lymphocytes to produce cytokines that antagonize atopy both in animal models and in man. Considering that atopy is the main risk factor for asthma, one can hypothesize that vaccination inducing T(H)1 responses, such as BCG, can be protective against asthma.

METHODS

OBJECTIVE

To estimate the association between neonatal BCG vaccination and prevalence of asthma among adolescents.

STUDY DESIGN

Cross-sectional study with schoolchildren aged 12-16 years. The presence of a scar compatible with BCG was used as a surrogate of neonatal vaccination. A self administered structured questionnaire was prepared based on that used by the International Study of Asthma and Allergies in Childhood. The prevalence of asthma was categorized according to the report of lifetime wheeze, lifetime asthma, lifetime asthma among those referring allergy and among those referring allergy and sneezing.

RESULTS

Neonatal BCG vaccination was not associated with the overall prevalence of reported wheezing or asthma. However, in the subgroup reporting current allergy and sneezing, neonatal BCG was associated with a 37% reduction of prevalence of lifetime asthma.

CONCLUSIONS

In the population we surveyed, neonatal BCG scar was associated with a reduction in the risk of asthma only in individuals with a past history suggestive of allergic rhinitis.

Development of atopy and wheezing symptoms in relation to heredity and early pet keeping in a Swedish birth cohort

The role of pet keeping during infancy for the development of allergy and asthma is still controversial. The objective of this population-based birth cohort study was to assess the development of atopy and different wheezing phenotypes during the first 4 yr of life in relation to heredity and early pet keeping. The cohort comprised all 1228 infants living in a Swedish county who were born over a 1-yr period. The parents replied to repeated questionnaires and 817 of the children were skin prick tested both at 1 and 4 yr. Cat keeping during the first year of life was associated with an increased risk of a positive skin prick test to cat at 1 yr of age [odds ratio (OR) 2.2, 95% confidence interval (CI) 0.9-5.6], but neither with sensitivity nor clinical symptoms of allergy at 4 yr. Dog keeping during the first year of life was associated with an increased risk of early-onset transient wheezing, but only in children with parental asthma (adjusted OR 4.3, 95% CI 1.5-12.1). In contrast, early dog keeping had an inverse association with sensitivity to pollen allergen at 4 yr (adjusted OR 0.3, 95% CI 0.1-0.9) and late-onset wheezing (adjusted OR 0.4, 95% CI 0.2-1.0). Thus, pet keeping during the first year of life was not associated with an increased risk of atopy at 4 yr, although a positive SPT to cat was more common at 1 yr. Our findings may even suggest that dog keeping during the first year of life might provide some protection from pollen allergy and late-onset wheezing and increase the risk of early-onset transient wheezing in children with heredity for asthma.

Snoring and its association with asthma in Indigenous children living in the Torres Strait and Northern Peninsula Area

OBJECTIVE

Respiratory health of Indigenous and minority ethnic groups in affluent countries is poorer than their non-minority counterparts and sleep disorders are no exception. In children, obstructive sleep apnoea has the potential to result in serious long-term consequences. In 1999, we studied 1650 children and adolescents living in the Torres Strait and the Northern Peninsula Area, Australia. Here we report prevalence of snoring in these communities and relate its association with asthma symptoms.

METHODS

A population-based cross-sectional study was conducted in the Torres Strait region. Five indigenous communities were randomly selected and information was collected using a structured face-to-face interview based on a standardized questionnaire. There was a 98% response rate, and 1650 children, 0-17 years of age, were included in the study.

RESULTS

Overall, the prevalence of snoring was 14.2% (95% CI 12.5-15.9); 3.6% (95% CI 2.7-4.6) reported snorting, and 6% (95% CI 4.9-7.2) reported restless sleep. The prevalence of snoring was significantly higher among males (17.1% for males and 10.8 for females, P = 0.005). Children were five times more likely to have experienced snoring and snorting if they reported wheezing in the last 12 months.

CONCLUSION

We conclude that the prevalence of symptoms suggestive of obstructive sleep problems is relatively high in children of this region. This highlights the need for awareness among the community patients and physicians about the problem of obstructive sleep-disordered breathing, especially in children with asthma, and for the need for further studies to measure prevalence of sleep breathing disorders among Indigenous Australians.

Prevalence of asthma and chronic respiratory symptoms among Alaska Native children

STUDY OBJECTIVES

To quantify the prevalence and impact of chronic respiratory symptoms among predominantly Alaska Native (AN)/American Indian (AI) middle school students.

DESIGN

School-based prevalence assessment using the International Study of Asthma and Allergy in Children survey, with supplemental video material and added questions about productive cough, exposure to tobacco smoke, and the functional impact of symptoms.

SETTING

The Yukon-Kuskokwim delta region of western Alaska.

PARTICIPANTS

A total of 466 children in the sixth to ninth grades, 81% of whom are AN/AI (377 children).

INTERVENTIONS

No study intervention.

RESULTS

Among the 377 AN/AI children, 40% reported one of the following three categories of chronic respiratory disease: physician-diagnosed asthma, 7.4%; asthma-like symptoms (ALS) without an asthma diagnosis, 11.4%; and chronic productive cough (CPC) without asthma diagnosis or symptoms, 21.5%. Symptom prevalence differed substantially between the largest town in the region and rural villages. After an adjustment for demographic factors, exposure to environmental tobacco smoke, active tobacco smoking, and self-report of atopy, village residents were 63% less likely to have ALS (p = 0.009), and had a twofold greater risk of CPC (p < 0.001) compared to children living in the town. Children with respiratory symptoms experienced sleep disturbances and accessed clinic visits for respiratory problems more often than did asymptomatic children.

CONCLUSIONS

Chronic respiratory symptoms are very common among AN children. CPC is an important nonasthmatic respiratory condition in this population. The differing patterns of respiratory illness within this region may help to elucidate the specific risk factors for asthma and chronic bronchitis in children.

Childhood asthma: healthcare resource utilisation in those with and without a diagnosis of the condition

AIM

To examine healthcare utilisation and the direct financial costs in providing medical care to a population of children aged 5-15 years with respiratory complaints. Secondarily, to assess whether these costs depended upon having specific asthma diagnosis or not.

METHOD

A postal respiratory questionnaire was sent to the parents or guardians of all children registered with two general practices. A search of the general practice medical records over a 2-year reference period was made for a stratified random sample and results are presented for 488 children aged 5-15 years.

RESULTS

The cost of primary care lower respiratory tract consultations in children with 4-5 symptoms/risk factors was pounds sterling 17.02 per patient per year for those with a previous diagnosis of asthma compared with pounds sterling 6.08 per patient per year for those with the same number of symptoms but no diagnosis (t = -4.446, P<0.001). The cost of primary care lower respiratory consultations in those with no GP diagnosis of asthma and no symptoms/risk factors was pounds sterling 2.25 per patient per year.

CONCLUSIONS

Studies, which fail to include the costs associated with treating children with respiratory symptoms but without a formal diagnosis, will seriously underestimate the costs of treating asthmatic children.

Climate and the prevalence of symptoms of asthma, allergic rhinitis, and atopic eczema in children

AIMS

To investigate the association between climate and atopic diseases using worldwide data from 146 centres of the International Study of Asthma and Allergies in Childhood (ISAAC).

METHODS

Between 1992 and 1996, each centre studied random samples of children aged 13-14 and 6-7 years (approx. 3000 per age group and centre) using standardised written and video questionnaires on symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema during the past 12 months. Data on long term climatic conditions in the centres were abstracted from one standardised source, and mixed linear regression models calculated to take the clustering of centres within countries into account.

RESULTS

In Western Europe (57 centres in 12 countries), the prevalence of asthma symptoms, assessed by written questionnaire, increased by 2.7% (95% CI 1.0% to 4.5%) with an increase in the estimated annual mean of indoor relative humidity of 10%. Similar associations were seen for the video questionnaire and the younger age group. Altitude and the annual variation of temperature and relative humidity outdoors were negatively associated with asthma symptoms. The prevalence of eczema symptoms correlated with latitude (positively) and mean annual outdoor temperature (negatively).

CONCLUSIONS

Results suggest that climate may affect the prevalence of asthma and atopic eczema in children.

Effect measures in prevalence studies

There is still considerable confusion and debate about the appropriate methods for analyzing prevalence studies, and a number of recent papers have argued that prevalence ratios are the preferred method and that prevalence odds ratios should not be used. These arguments assert that the prevalence ratio is obviously the better measure and the odds ratio is "unintelligible." They have often been accompanied by demonstrations that when a disease is common the prevalence ratio and the prevalence odds ratio may differ substantially. However, this does not tell us which measure is the more valid to use. In fact, the prevalence odds ratio a) estimates the incidence rate ratio with fewer assumptions than are required for the prevalence ratio; b) can be estimated using the same methods as for the odds ratio in case-control studies, namely, the Mantel-Haenszel method and logistic regression; and c) provides practical, analytical, and theoretical consistency between analyses of a prevalence study and prevalence case-control analyses based on the same study population. For these reasons, the prevalence odds ratio will continue to be one of the standard methods for analyzing prevalence studies and prevalence case-control studies.

Atopic dermatitis and respiratory symptoms in Russian and northern Norwegian school children: a comparison study in two arctic areas and the impact of environmental factors

BACKGROUND

The increase in atopic diseases during recent decades has been related to environmental factors such as indoor and outdoor pollution and the ingestion of certain foods. On the other hand, studies from Eastern Europe (with heavy air pollution) have reported a lower prevalence of atopic diseases and sensitization in their schoolchildren than in children living in Western Europe.

OBJECTIVES

This study compares the frequency of atopic diseases and respiratory symptoms in two geographically close arctic areas and points to possible risk factors for development of the diseases.

METHODS

A total of 1734 schoolchildren (1183 in Nikel and 551 in Sør-Varanger) were studied using identical, four-page, self-administered questionnaires.

RESULTS

Atopic diseases were reported in 38.7% of Norwegian and in 24.2% of Russian children (P < 0.001). Atopic dermatitis (AD) (23.6% vs 7.9%; P < 0.001) and allergic rhinoconjunctivitis (AR) (20.6% vs 14.7%; P < 0.001) occurred more frequently in Sør-Varanger, whereas 'self-reported' asthma (12.3% vs 13.1%) was similar in both areas. However, respiratory symptoms such as coughing, wheezing, breathlessness and bronchitis were 3-4 times more frequent in Nikel (P < 0.001).

CONCLUSION

This study disproves a previous hypothesis, i.e. that air pollution must be a major risk factor for the development of atopic diseases. Nevertheless, respiratory tract symptoms may be provoked by environmental pollution. Possible explanations for the higher frequency of atopic diseases in Sør-Varanger may be found in socio-economic and lifestyle differences between the two populations.