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

CD4+IL13+ T lymphocytes at birth and the development of wheezing and/or asthma during the 1st year of life

BACKGROUND

Despite our knowledge that maternal inheritance influences the development of asthma in childhood, attempts to identify a clear-cut Th2-oriented cytokine production by T lymphocytes at birth have given conflicting results. The prognostic significance of these cells for asthma development later in life remains to be determined.

METHODS

We evaluated at the single cell level Th1- and Th2-type cytokines in 208 randomly selected cord blood mononuclear cell (CBMC) samples obtained from pregnant women (group A, n = 68 with diagnosed respiratory allergic disease; group B, n = 140, with no evidence of atopy), and prospectively followed newborns for 1 year.

RESULTS

There was no difference in IFN-gamma, IL-4 and IL-5 production at birth between both groups, whereas a correlation between CD4+IL13+ lymphocytes from CBMC samples derived from atopic mothers and the occurrence of wheezing and/or asthma during the 1st year of life was found.

CONCLUSIONS

Our observations suggest that the intracellular cytokine profile of cord blood CD4+ cells, in terms of IL-13 production, could be considered a useful tool for a more accurate identification of newborns from atopic mothers who are at high risk of developing asthma.

Gibbs sampling-based segregation analysis of asthma-associated quantitative traits in a population-based sample of nuclear families

Asthma is a common, complex human disease. Elevated serum immunoglobulin E (IgE) levels, elevated blood eosinophil counts, and increased airway responsiveness are physiological traits that are characteristic of asthma. Few studies have investigated major gene effects for these traits in a population-based sample. Further, it is not known if any putative major genes may be common to two or more of these traits. We investigated the existence and nature of major genes modulating asthma-associated quantitative traits in an Australian population-based sample of 210 Caucasian nuclear families. The sharing of these major genes was also investigated. Segregation analysis was based upon a Markov Chain Monte Carlo (Gibbs sampling) approach as implemented in the program BUGS v0.6. All models included adjustment for age, height, tobacco smoke exposure, and gender. The segregation of total IgE levels, blood eosinophil counts, and dose-response slope (DRS) of methacholine challenge were all consistent with major loci at which a recessive allele acted to increase or decrease the phenotype. The respective estimated frequencies of the recessive alleles were 68% (total IgE), 10% (blood eosinophil count), and 27% (DRS). Extensive modelling suggested that the major loci controlling total serum IgE levels, blood eosinophil counts, and airway responsiveness represent different genes. These data provide evidence, for the first time, of the existence of at least 3 distinct genetic pathways involving major gene effects on physiological traits closely associated with asthma. These results have implications for gene discovery programs.

International Study of Asthma and Allergies in Childhood: validation of the rhinitis symptom questionnaire and prevalence of rhinitis in schoolchildren in São Paulo, Brazil

Written questionnaires (WQ) have been widely used in epidemiologic studies. In order to yield comparable results, they must be validated after translation to another language. The International Study of Asthma and Allergies in Childhood (ISAAC) WQ has been previously validated by a comprehensive study, but its validation in Brazil has not been performed. Our objectives were to validate the rhinitis component of the ISAAC's self-applicable WQ following its translation to Portuguese, and to determine the prevalence of rhinitis and related symptoms among Brazilian children living in the city of São Paulo. A group of 10 pediatricians and 10 pediatric allergists graded the questions from 0 to 2 and established a maximum score for each question. The WQ was answered by parents or guardians of children 6-7 years of age with rhinitis (R) (n = 27) and of control children of the same age without rhinitis (C) (n = 27). The WQ was also completed by adolescents 13-14 years of age with rhinitis (R) (n = 32) and without rhinitis (C) (n = 32). Half of these individuals answered the same WQ after 2-4 weeks, to ensure reproducibility. Cut-off scores of 4 and 3 were identified for the 6-7- and 13-14-year-old groups, respectively, as scores predictive of rhinitis. The prevalence of rhinitis was 28.8% in the group of 3005 children 6-7 years of age and 31.7% in the group of 3008 children 13-14 years of age, respectively. Using the global cut-off score, these prevalences were even higher, in the order of 34.7% and 40.7%, respectively. In conclusion, the rhinitis component of the ISAAC WQ was proven to be reproducible, adequate and able to discriminate children and adolescents with and without rhinitis, and revealed that the prevalence of rhinitis among Brazilian children living in the city of São Paulo was as high as the prevalence of rhinitis in other areas of the world.

Prevalence of bronchial asthma and allergic rhinitis in Istanbul school children

The aim of this study was to determine the prevalence of asthma, allergic rhinitis and their related symptoms in Istanbul and to investigate the effect of socioeconomic status on the prevalence of asthma and allergic rhinitis and whether there are differences between the prevalence of childhood asthma in the same and different regions as found in previous studies and our own. The study period was the 1996-1997 school year in three primary schools in Istanbul. For proportional representation of high, middle, and low socioeconomic levels, the schools were selected from three different regions of Istanbul. A translated version of the International Study of Asthma and Allergies in Childhood (ISAAC) was used. The questionnaire was distributed to the parents of 2600 students aged 6-15 years. All of the 2276 children whose parents responded were included in the survey. The overall cumulative and current prevalences of wheezing were 13.7 and 7.2% respectively and the overall cumulative prevalence of allergic rhinitis was 17.6%. There was no statistically significant difference between asthmatics and non-asthmatics by sex, socioeconomic status and passive smoking. Family history of atopy was found to be significantly higher in asthmatics. Although there are differences in the results of studies concerning the prevalence of asthma and allergic rhinitis not only between different countries but also between different regions of the same city, by using a standardized international method, the actual values may be obtained.

Diet and asthma, allergic rhinoconjunctivitis and atopic eczema symptom prevalence: an ecological analysis of the International Study of Asthma and Allergies in Childhood (ISAAC) data. ISAAC Phase One Study Group

Several studies have suggested that the increasing prevalence of symptoms of asthma, rhinitis and eczema, could be associated with dietary factors. In the present paper, a global analysis of prevalence rates of wheeze, allergic rhinoconjunctivitis and atopic eczema was performed in relation to diet, as defined by national food intake data. Analyses were based on the International Study of Asthma and Allergies in Childhood (ISAAC) data for 6-7 and 13-14 yr old children. Symptoms of wheeze, allergic rhinoconjunctivitis and atopic eczema symptom prevalence were regressed against per capita food intake, and adjusted for gross national product to account for economic development. Dietary data were based on 1995 Food and Agriculture Organisation of the United Nations data for 53 of the 56 countries that took part in ISAAC phase I (1994/1995). The 13-14 year age group showed a consistent pattern of decreases in symptoms of wheeze (current and severe), allergic rhinoconjunctivitis and atopic eczema, associated with increased per capita consumption of calories from cereal and rice, protein from cereals and nuts, starch, as well as vegetables and vegetable nutrients. The video questionnaire data for 13-14 yr olds and the ISAAC data for 6-7 yr olds showed similar patterns for these foods. A consistent inverse relationship was seen between prevalence rates of the three conditions and the intake of starch, cereals, and vegetables. If these findings could be generalised, and if the average daily consumption of these foods increased, it is speculated that an important decrease in symptom prevalence may be achieved.

Prevalence of atopic dermatitis, asthma, allergic rhinitis, and hand and contact dermatitis in adolescents. The Odense Adolescence Cohort Study on Atopic Diseases and Dermatitis

BACKGROUND

Atopic diseases are common in children and adolescents. However, epidemiological knowledge is sparse for hand eczema and allergic contact dermatitis in this age group. Furthermore, no population-based studies have evaluated the prevalence of atopic diseases and hand and contact dermatitis in the same group of adolescents.

OBJECTIVES

To assess prevalence measures of atopic dermatitis (AD), asthma, allergic rhinitis and hand and contact dermatitis in adolescents in Odense municipality, Denmark.

METHODS

The study was carried out as a cross-sectional study among 1501 eighth grade school children (age 12-16 years) and included questionnaire, interview, clinical examination and patch testing.

RESULTS

The lifetime prevalence of AD was 21.3% (girls 25.7% vs. boys 17.0%, P < 0.001) using predefined questionnaire criteria. The 1-year period prevalence of AD was 6.7% and the point prevalence 3.6% (Hanifin and Rajka criteria). In the interview the lifetime prevalence of inhalant allergy was estimated as 17.7% (6.9% allergic asthma, 15.7% allergic rhinitis). The lifetime prevalence of hand eczema based on the questionnaire was 9.2%, the 1-year period prevalence was 7.3% and the point prevalence 3.2%, with a significant predominance in girls. A significant association was found both between AD and inhalant allergy, and between AD and hand eczema using lifetime prevalence measures. The point prevalence of contact allergy was 15.2% (girls 19.4% vs. boys 10.3%, P < 0.001), and present or past allergic contact dermatitis was found in 7.2% (girls 11.3% vs. boys 2.5%). Contact allergy was most common to nickel (8.6%) and fragrance mix (1.8%).

CONCLUSIONS

High prevalence figures were found for atopic diseases, hand eczema and allergic contact dermatitis, and the diseases were closely associated. A considerable number of adolescents still suffers from AD, and a considerable sex difference was noted for hand eczema and allergic contact dermatitis. Nickel allergy and perfume allergy were the major contact allergies. In the future this cohort of eighth grade school children will be followed up with regard to the course and development of atopic diseases, hand eczema and contact dermatitis.

Higher occurrence of asthma-related symptoms in an urban than a suburban area in adults, but not in children

In young adults, a higher occurrence of asthma-related symptoms was found in an urban than an adjacent suburban area in a survey performed in 1991. The authors now wondered whether such differences could be established in other age groups. The present study (in 1996) included 14,299 subjects, aged 5-75 yrs, of a random sample of the general population in the same two adjacent areas: the centre of Antwerp (Belgium) and its south suburban border. The standardized European Community Respiratory Health Survey (ECRHS) and International Study of Asthma and Allergies in Childhood (ISAAC) questionnaires were used to assess the occurrence of asthma-related symptoms. Higher rates were confirmed in urban compared to suburban Antwerp in adults (20-75 yrs), but no such area differences were found in children (5-8 and 12-15 yrs). Adjustment for a number of recorded risk factors did not seem to affect the area differences in asthma-related symptoms. Comparing the survey results of 1991 and 1996 in 20-44 yr old adults, the findings suggest a slight increase in reported respiratory symptoms in both areas. A higher occurrence of asthma symptoms was observed in the urban than suburban area in adults, but not in children. This might be explained by a progressive effect of long-term exposure to the "urban environment". However, longitudinal studies are necessary to further clarify the factors accounting for these age-related area differences.

Incidence and remission of asthma in schoolchildren: report from the obstructive lung disease in northern Sweden studies

OBJECTIVE

An increasing prevalence of asthma has been reported worldwide as well as in Sweden. In 1996, the prevalence of asthma and type 1 allergy was investigated in a cohort of 3525 children 7 and 8 years old in 3 areas of northern Sweden. The aim of the present study was to estimate the incidence of asthma and to identify risk factors for incident cases over 1 year.

METHODS

The study started with a parental questionnaire, the International Study of Asthma and Allergies in Childhood questionnaire with additional questions, a skin prick test, and a validation study. The cohort was followed up after 1 year with the same questions. The response rate to the questionnaire was 97% in 1996, and 3339 children (97%) participated both in 1996 and 1997.

RESULTS

The incidence of physician-diagnosed asthma was 0.9/100/year; of wheezing, 3.8/100/year; and of new frequent or daily users of asthma medicines, 1.1/100/year. There was no difference by sex. The risk factor pattern based on incident cases of asthma was different from that based on prevalent cases. Significant risk factors for incident asthma were a positive skin test (odds ratio [OR]: 9.3; 95% confidence interval [CI]: 3.8-22.7); low birth weight (OR: 7.4; 95% CI: 2.2-24.5); and family history of asthma (OR: 2.6; 95% CI: 1.1-6.3). Having or having had pets at home was associated with a decreased risk for asthma and wheezing based on prevalent cases, although it was associated with an increased risk for incidence of wheezing (OR: 2.9; 95% CI: 1.3-6.2). Remission of asthma, which was reported by 10% of the children with current asthma during 1 year, was associated with a negative skin test.

CONCLUSION

The incidence of asthma at the age of 8 years was high, but remission was also common. Important risk factors for the development of asthma at this age were type 1 allergy, low birth weight, and family history of asthma. Furthermore, the results suggest that in a region where sensitivity to domestic animals is a strong risk factor for asthma, the presence of pets in the home may have different effects in early childhood compared with later in childhood.

Asthma, inhaled corticosteroid use, and bone mass in prepubertal children

The aim of this cross-sectional study was to describe the role of asthma, asthma severity, and medication usage in bone mineralization of prepubertal children. Asthma severity, medication usage, and physical activity were assessed by questionnaire and objective measures in 330 children. Bone densitometry and body composition were measured by dual-energy x-ray absorptiometry. Asthma ever was reported by 110 subjects (33%). A diagnosis of asthma was not associated with any deficit in bone mass, whereas usage of inhaled corticosteroids (ICS) in the last year (but not past use) was associated with deficits in bone in the total body (only after adjustment for confounders), particularly for doses of > or =400 microg/day. These observations support current recommendations with regard to ICS usage in children, but require confirmation in longitudinal studies.

Sensitization and exposure to pet allergens in asthmatics versus non-asthmatics with allergic rhinitis

In sensitized subjects with allergic rhinitis (AR) or asthma, allergen exposure provokes symptoms. Among non-asthmatics with AR, an association between allergen sensitization, pollen season and lower airway inflammation has been demonstrated. Our aims were to compare AR and asthma with regard to patterns of allergen sensitization, the degree of airway hyperresponsiveness (AHR) and levels of exhaled nitric oxide (ENO). Finally, we wanted to relate our findings to previous or current exposure to household pets. Four hundred and thirty-one adolescents with different clinical phenotypes were randomly selected from a large-scale epidemiological survey. They were investigated with allergy screening, measurements of ENO and a methacholine bronchoprovocation test. Sensitization to pet allergens (cat, dog and horse) was associated with increased AHR and ENO both in asthmatics and non-asthmatics with AR. The risk of being sensitized to cat allergens was significantly reduced in those who had kept cats vs. those who had never kept them. Keeping dogs or horses did not influence the risk of being sensitized to the respective allergens. Only in steroid-naive, non-smoking asthmatics, a trend towards increased ENO in those sensitized and exposed to cat or dog allergens was seen. Although sensitization towards pet allergens was associated with inflammation in the lower airways irrespective of clinical phenotype, keeping pets did not increase the risk of being sensitized to pet allergens.

Parents' quality of life and respiratory symptoms in young children with mild wheeze. EASE Study Group

The Paediatric Asthma Caregiver's Quality of Life Questionnaire (PACQLQ), measures the impact of child asthma symptoms on family activity (CGAct) and parental anxiety (CGEmot). It has not been validated for families of children <7 yrs, with wheezing illness. This study assessed the sensitivity of the PACQLQ to symptom change in 62 preschool children with wheezing illness. The median age of children was 3 yrs (range 0.8-6 yrs). At entry and 3-month follow-up, parents recorded child respiratory symptoms in a 1-month diary and completed the PACQLQ. On average, children in the study had 7 symptomatic days per month. On entry, mothers < or = 30 yrs had worse scores than those > 30 (p < 0.02), and mothers in less affluent socioeconomic groups had worse scores than those in higher groups (p = 0.05). Change in symptom scores and symptom free days between entry and follow-up was associated with change in PACQLQ scores (r = 0.54-0.57, p <0.001). Thirty-three parents had absolute change in PACQLQ of <0.5 over three months (which has been previously defined as not being clinically significant). Compared to parents with higher PACQLQ change, parents with PACQLQ scores <0.5, did not differ in frequency of child symptoms or in social-demographic factors, but had better quality of life scores on entry to the study (p<0.01). It is concluded that the Paediatric Asthma Caregiver's Quality of Life Questionnaire is sensitive to group measures of child symptom change over 3 months, among preschool children, and this supports its use as an outcome measure in clinical trials. The absolute impact of child symptoms on parent quality of life varies among parents.

Prevalence of asthma and other allergic diseases in an adolescent population: association with gender and race

OBJECTIVES

To estimate the prevalence and severity of asthma in an adolescent population by sex and race.

METHODS

Cross-sectional, population-based survey of school children.

SETTING

Midwestern city experiencing damage from the 1993 Mississippi River flood.

PARTICIPANTS

2,693 children attending grades 7 to 12.

MEASUREMENTS

Questions from the International Study of Asthma and Allergies in Childhood (ISAAC).

RESULTS

Two thousand six hundred ninety-three children were surveyed, for a response rate of 90%. In this population, 16.4% reported having ever been diagnosed with asthma; 25% reported wheezing in the last 12 months; 32% reported symptoms of rhinitis in the last 12 months; and 22% reported ever having hay fever. The prevalence rate for current asthma was 12.6%. Female students had significantly greater prevalence rates for current asthma (16.4% vs 9.0%, OR = 1.85); ever-diagnosed asthma (18.5% vs 14.3%, OR = 1.36); wheezing > or = 4 times in the last 12 months (12.0% vs 5.6%, OR = 1.95); current rhinitis (38.7% vs 25.4%, OR = 1.73); and hay fever (26.4% vs 18.4%, OR = 1.57). All associations with sex remained significant, except ever-diagnosed asthma, after controlling for other known risk factors in logistic regression. African-Americans had higher prevalence rates than other races with differences reaching statistical significance for ever-diagnosed asthma and current asthma; however, these relationships did not remain significant after controlling for other known risk factors in logistic regression.

CONCLUSIONS

Our prevalence rates were similar to those reported by other studies that used the ISAAC questionnaire. Female students reported significantly more asthma, wheezing, rhinitis, and hay fever than male students. Female students also reported more severe symptoms and a greater number of emergency room and hospital admissions.

Bronchial hyperresponsiveness to 4.5% hypertonic saline indicates a past history of asthma-like symptoms in children

SUMMARY. To evaluate the importance of a past history of asthma-like symptoms over a period of 2 years and current bronchial hyperreactivity (BHR), 538 randomly selected schoolchildren, initially aged 7-8 years, were examined. At yearly intervals, three standardized questionnaires, including items from the ISAAC panel, were answered by parents. Following the last questionnaire, BHR to 4.5% hypertonic saline (HS) was recorded. In survey 1, lifetime prevalence of asthma was 4.9%. During the 12-month period, prevalence of wheeze and dyspnea ranged between 9.3 and 5.2% (Survey 1) and 5.9% and 4.4% (Survey 2). Among children with wheeze or dyspnea in Survey 3, BHR (defined as a fall of baseline FEV(1) > or = 15%) was significantly more frequent (50.0% and 60.7%, respectively) than among children without these symptoms (12.8%, P < 0.001, and 12.8%, P < 0.001, respectively). The negative predictive value of BHR to have neither wheeze nor dyspnea was about 88% and did not vary throughout the study (Survey 1, 87%; Survey 2, 88%; Survey 3, 88%). The relative risk of showing BHR was significantly increased in children with wheeze (survey 2, odds ratio (OR) 3.0 (95% confidence interval (CI) 1.0-8.7)) or dyspnea (Survey 1: OR 5.9 (95% CI 1.9-18.5), Survey 3: 5.2 (1.7-16.2), but not in children with dry cough or nocturnal cough (data not shown). Wheeze and dyspnea occurred repeatedly in the same individuals with BHR in a high percentage of children (83.3% and 76.5%, respectively). In conclusion, there is a strong association between recent and previous dyspnea and current BHR, and it indicates intraindividual persistence of symptom history.

Using single nucleotide polymorphisms as a means to understanding the pathophysiology of asthma

Asthma is the most common chronic childhood disease in the developed nations, and is a complex disease that has high social and economic costs. Studies of the genetic etiology of asthma offer a way of improving our understanding of its pathogenesis, with the goal of improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect specific polymorphisms in genetic loci contributing to asthma susceptibility. Concomitantly, the technology for detecting single nucleotide polymorphisms (SNPs) has undergone rapid development, extensive catalogues of SNPs across the genome have been constructed, and SNPs have been increasingly used as a method of investigating the genetic etiology of complex human diseases. This paper reviews both current and potential future contributions of SNPs to our understanding of asthma pathophysiology.

Survey of respiratory sounds in infants

BACKGROUND

Over the last decade there has been an apparent increase in childhood wheeze. We speculated that much of the reported increase may be attributed to the term wheeze being adopted by parents to describe a variety of other forms of noisy breathing.

AIMS

To investigate terminology used by parents to describe their children's breath sounds.

METHODS

An interview was carried out with the parents of 92 infants with noisy breathing, beginning with an open question and then directed towards a more detailed description. Finally, the parents were asked to choose from a wheeze, ruttle, and stridor on imitation by the investigator and video clips of children.

RESULTS

Wheeze was the most commonly chosen word on initial questioning (59%). Only 36% were still using this term at the end of the interview, representing a decrease of one third, whereas the use of the word ruttles doubled.

CONCLUSIONS

Our results reflect the degree of inaccuracy involved in the use of the term wheeze in clinical practice, which may be leading to over diagnosis. Imprecise use of this term has potentially important implications for therapy and clinical trials.

Pulmonary sequelae in long-term survivors of bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a common problem in premature babies. Long-term sequelae are the main concerns.

METHODS

A retrospective review of all BPD children born in Queen Mary Hospital, a teaching hospital of the University of Hong Kong, from January 1987 to December 1995 was conducted. Children with cerebral palsy, immunodeficiency, congenital heart disorders, renal or liver failure were excluded from analysis. Chest radiography (CXR), electrocardiogram (ECG) and pulse oximetry were routinely performed.

RESULTS

Fifty-five children completed the study. The female to male ratio was 1:1.1. The mean gestational age was 28 weeks. Twenty-five children were born with a birthweight of less than 1001 g. Mean age at assessment was 5.4 years. Twenty-four children (44%) demonstrated signs or symptoms of current asthma. Only seven children managed to perform the spirometry satisfactorily. One child had low forced vital capacity and one had hyperresponsive airway. The only risk factor found to be associated with current asthma was the birth month, with those children born early in the year at higher risk of developing current asthma. Seventeen of 48 children (35%) had a bodyweight below the third percentile at the corrected age of 1 year. Eleven of these seventeen children (65%) demonstrated catch-up growth at assessment. Abnormal CXR was found in 25 of 40 children (63%). All had normal pulse oximetry and ECG.

CONCLUSIONS

Bronchopulmonary dysplasia children had a significantly higher risk than the general population of developing current asthma (odds ratio 4.7; 95% confidence interval 3.4-6.5; P<0.0001). The importance of birth month suggests that early life experience is important in the pathogenesis of asthma, even in BPD children. The long-term growth of BPD children was much better than previously reported.

Prevalence of asthma symptoms in Latin America: the International Study of Asthma and Allergies in Childhood (ISAAC)

The prevalence of respiratory symptoms indicative of asthma in children from Latin America has been largely ignored. As part of the International Study of Asthma and Allergies in Childhood (ISAAC), 17 centers in 9 different Latin American countries participated in the study, and data from 52,549 written questionnaires (WQ) in children aged 13-14 years and from 36,264 WQ in 6-7 year olds are described here. In children aged 13-14 years, the prevalence of asthma ever ranged from 5.5-28%, and the prevalence of wheezing in the last 12 months from 6.6-27%. In children aged 6-7 years, the prevalence of asthma ever ranged from 4.1-26.9%, and the prevalence of wheezing in the last 12 months ranged from 8.6-32.1%. The lower prevalence in centers with higher levels of atmospheric pollution suggests that chronic inhalation of polluted air in children does not contribute to asthma. Furthermore, the high figures for asthma in a region with a high level of gastrointestinal parasite infestation, and a high burden of acute respiratory infections occurring early in life, suggest that these factors, considered as protective in other regions, do not have the same effect in this region. The present study indicates that the prevalence of asthma and related symptoms in Latin America is as high and variable as described in industrialized or developed regions of the world.

Prevalence of asthma and rhinitis in relation to long-term exposure to gaseous air pollutants

The relationship between long-term exposure to air pollutants, especially with regard to photochemical air pollutants, and asthma prevalence in developed countries is controversial. The objective of this cross-sectional survey was to compare mean levels of the main gaseous air pollutants and prevalence rates of rhinitis, asthma, and asthmatic symptoms. It included 2,445 children from the 8th and 9th school grades who had been living for at least 3 years in an area where some communities undergo the heaviest photochemical exposure in France. Data on rhinitis, asthmatic symptoms, and asthma prevalence were gathered with the ISAAC paper and video questionnaires. The relation between level of air pollutants and asthma was assessed first by comparison of crude prevalence rates (chi-square test), and then by simple regression analysis and multiple logistic regression analysis. No consistent association between mean SO2 and NO2 levels, and prevalence of rhinitis, asthma, or asthmatic symptoms could be demonstrated. In contrast, there were statistically significant associations between prevalence of asthmatic symptoms and mean ozone O3) concentration. The interpretation of such findings is not straightforward, as these symptoms can be interpreted either as respiratory irritation due to exposure to nonspecific airway stimuli or as a true asthmatic state. Additional studies are required to clarify this important issue. In conclusion, this large cross-sectional epidemiologic survey performed in an area of high photochemical air pollution did demonstrate statistically significant associations between the prevalence of asthmatic symptoms and mean O3 concentration.

Is childhood allergy more common amongst an island population?

A rise in the prevalence of childhood asthma has been reported in both the UK and in several overseas countries during recent years. Wide geographical variations have also been demonstrated in the distribution of hay fever, atopic eczema and other allergic symptoms. It is the impression of many parents and some clinicians that allergic symptoms may be even higher amongst children in an island environment compared with a similar population on the mainland. To test this hypothesis, Guernsey and Jersey in the Channel Islands, and the Isle of Man in the Irish Sea participated as an independent arm in the International Study of Asthma and Allergy in Childhood (ISAAC). This entailed self-completion of a 38-part pretested and validated questionnaire in a classroom setting under standardised conditions. A total of 3,772 secondary students in school years eight and nine living in the three islands were compared with 27,507 students of similar age in 93 British secondary schools enrolled in the larger UK study. There are a number of demonstrable differences in climate, home environment and lifestyle factors between the islands and mainland UK. Although results were generally above the UK mean, they were comparable with the reference region of South West England and invariably below the UK maximum. For instance, the prevalence of 'ever wheezed?', 'wheezed in last twelve months?', 'wheezed with exercise?' and 'diagnosis of asthma' were a mean of 50.5%, 34.5%, 31% and 19.7% in the islands compared with a UK prevalence of 48.8%, 33.3%, 28.5% and 20.7%, whilst the prevalence of 'runny nose ever?' and 'runny nose in last twelve months?' was a mean of 46.6% and 36.7% in the islands, compared with 47.1% and 37.9% in the UK mean. These differences were not statistically significant. This information will be reassuring to parents of island children, and also demonstrates that services for the management of asthma and other allergic conditions should not be a higher public health priority in these locations than on the mainland of Britain.

Early introduction of inhaled steroids in wheezing children presenting in primary care. A pilot study. EASE Study Group

BACKGROUND

Recurrent wheezing illness in childhood is a frequent reason for consultation in both primary and secondary care and whilst there is widespread support for the earlier introduction of inhaled corticosteroids (ICS) concerns remain about potential adverse systemic effects.

OBJECTIVE

We sought to identify the feasibility and size of study required to assess the benefits, adverse effects and cost-effectiveness of early introduction of ICS.

METHODS

We entered 86 children (mean age 4.5 years) with at least two consecutive wheezing episodes into a pragmatic randomized controlled trial. All children were already being prescribed beta2-agonist and those allocated to ICS were prescribed twice daily beclomethasone dipropionate 200 microg or budesonide 200 microg. At entry and 3 and 6 months age appropriate lung function (FEV(1), T(ptef):T(e)), respiratory symptoms, quality of life of children and carers, growth and sexual maturation, bone mass and bone turnover, and health care costs were assessed.

RESULTS

Drop out rate was 8% (7 of 86). No significant differences were found in FEV(1) or T(ptef):T(e) at 6 months. Respiratory symptoms and health-related quality of life of children and carers improved equally in both groups. No significant differences were found in growth rates or in bone mass. In the ICS group markers of bone turnover (Pyd:Cr) fell (271 vs 237 nmol/mmol) in contrast to a rise in those on beta(2) alone (255 vs 319 nmol/mmol) P < 0.05. Combined health care costs were higher in the ICS group.

CONCLUSIONS

The low drop out rate provided evidence that the protocol was practical and acceptable. In order to confirm these results, and using the same study design, power estimates indicated that 260 children would need to be randomized.

Prevalence and predictors of rhinitis in Danish children and adolescents

BACKGROUND

The prevalence of self-reported symptoms of allergic rhinitis is increasing in many countries, but the reasons for this trend are not well understood. Data from a 6-year follow-up study of a population sample of children and adolescents (n=408), aged 7-17 years at enrolment in 1986, were analyzed to investigate the prevalence and predictors of self-reported rhinitis.

METHODS

Case history was used to assess the presence or absence of rhinitis (sneezing and running or blocked nose not associated with a cold), asthma, and eczema. Pulmonary function, skin prick test reactivity, and airway responsiveness to histamine were measured in all participants; a screening test for IgE antibodies to common allergens (Magic Lite SQ, Allergy Screen, ALK, Denmark) was performed in 237 (58%) of the participants.

RESULTS

The point prevalence of rhinitis increased from the first to the second survey, 14% and 22%, respectively; 54 (13%) of the subjects reported rhinitis only at the second survey (new rhinitis). Confining the analysis to participants without symptoms of rhinitis at the first survey showed that self-reported eczema (relative risk [RR] 2.3, 95% confidence interval [CI] 1.2-4.7), airway hyperresponsiveness (RR 2.5, CI 1.8-3.0), atopy to grass pollen (RR 2.6, CI 1.7-3.3), atopy to dog dander (RR 2.4, CI 1.6-3.3), and atopy to house-dust mite (RR 2.7, CI 1.4-5.2) at the first survey predicted an increased risk of the presence of rhinitis at the second survey. A positive Allergy Screen test at enrollment was associated with an increased risk of self-reported rhinitis at follow-up (RR 2.4, CI 1.4-3.4).

CONCLUSIONS

This longitudinal population study of children and adolescents showed an age-related increase in the point prevalence of self-reported rhinitis; furthermore, sensitization to common aeroallergens, airway hyperresponsiveness, and the presence of self-reported eczema were significantly associated with an increased risk of subsequent development of rhinitis.

Wheezing in early life and asthma at school age: predictors of symptom persistence

Early childhood wheezing is associated with asthma later in life. However, the high spontaneous recovery rate and the lack of firm predictors for persistence of wheezing complicates the development of evidence-based guidelines for long-term management of wheezy infants and toddlers. Our aim was to define variables that could be used to identify wheezy individuals younger than 3 years of age who would continue to be symptomatic at school age. The method used was a questionnaire-based cross-sectional survey of 2,027 randomly chosen, 6-13-year-old school children. Altogether 1,829 (90%) questionnaires were returned. Emergency medical care had been sought for 186 (10.2%) children for wheezing during the first 3 years of life, and only 17.2% of these children had received similar emergency treatment during the 12 months preceding the survey. The total proportion of children with current asthma at school age was 11.4%. A logistic regression analysis indicated that for the early wheezers, a family history of asthma, an itchy rash or food allergy, and exposure to tobacco smoke at home before the age of 3 years, were all independently associated with symptom persistence until school age. Among all wheezy children younger than 3 years, those who have a history of food allergy, itchy rash, asthma occurrence in a sibling or parent, or are exposed to tobacco smoke during the first years of life are at highest risk for symptom persistence until school age.

Practical evaluation of asthma exacerbation self-management in children and adolescents

The objective of this study was to describe asthma exacerbation self-management in children and adolescents. We used a cross-sectional study population enrolled in the International Study of Asthma and Allergies in Childhood (ISAAC) in Bordeaux. Subjects answered an additional questionnaire on utilization of health services, self-evaluation of usual asthma exacerbation severity and home management of asthma exacerbation. Criteria used for selecting patients were both having asthma confirmed by a physician and having had suffered from symptoms during the past year. Children and adolescents attended similar health services for managing their asthma but compliance to anti-asthmatic treatment was better in children than in adolescents. Among the children 4.8% had asthma and 6.2% of adolescents had asthma, as diagnosed by a doctor. Of the children, 72.3% and of the adolescents 54.7% had less than one asthma attack per month. In cases of mild asthma exacerbation, 38.7% of adolescents and 9.3% of children waited until the end of exacerbation without taking any medication. The proportion of children not receiving any treatment was lower when symptoms were more severe but this was not the case in adolescents. Although most of the patients used were taking beta2-agonist, we found that 21-43% of children or adolescents did not receive appropriate medication in the event of asthma exacerbation. These results demonstrate that (i) asthma exacerbation self-management is related to self-assessed severity of symptoms and that (ii) a large proportion of asthmatic children in the community, and particularly adolescents, do not therefore receive appropriate treatment in the event of asthma exacerbation.

Does the use of antibiotics in early childhood increase the risk of asthma and allergic disease?

BACKGROUND

One of the mechanisms evoked to explain the increasing prevalences of asthma and allergy, in particular among children, is the 'Western lifestyle' or 'hygiene' hypothesis. As early childhood infections are assumed to hold a protective effect on the development of asthma and allergies, the use of antibiotics at that sensitive age may lead to an increased risk of asthma and allergy.

OBJECTIVE

The aim of this study is to investigate the association between the use of antibiotics in the first year of life and the subsequent development of asthma and allergic disorders.

METHODS

In a population-based sample of 7-and-8-year-old children questionnaire and skin prick test data were collected from 1206 and 675 subjects, respectively. Prevalence rates of asthma, allergic disorders and skin test positivity were compared between children with and without early life use of antibiotics, taking into account other possible risk factors including early respiratory infections. The effect of genetic predisposition was investigated by stratified analyses of children with and without parental hay fever.

RESULTS

The use of antibiotics during the first year of life was significantly associated with asthma (OR = 1.7, 95% CI 1.0-3.1), hay fever (OR = 2.3, 95% CI 1.3-3.8) and eczema (OR = 1.3, 95% CI 1.0-1.8). No significant relationship was found with skin test positivity (OR = 1.1, 95% CI 0.7-1.7). After stratification for the presence of parental hay fever, children without parental hay fever did not show any significant associations between antibiotics use and asthma or allergy, whereas in children with parental hay fever the use of antibiotics was significantly related with asthma (OR = 2.3, 95% CI 1.1-5.1), hay fever (OR = 2.8, 95% CI 1.5-5.1) and eczema (OR = 1.6, 95% CI 1.0-2.6), and of borderline statistical significance with skin test positivity (OR = 1.6, 95% CI 0.9-3.0).

CONCLUSION

Early childhood use of antibiotics is associated with an increased risk of developing asthma and allergic disorders in children who are predisposed to atopic immune responses. These findings support recent immunological understanding of the maturation of the immune system.

Association and linkage of atopic dermatitis with chromosome 13q12-14 and 5q31-33 markers

Atopic dermatitis is a chronic inflammatory skin disease that affects 10-20% of the population. Linkage of atopy, asthma, allergic rhinitis, and total serum IgE levels to several different chromosomal regions have been described extensively, but little is known about the genetic control of atopic dermatitis. We tested for the association and linkage between atopic dermatitis and five chromosomal regions: 5q31-33, 6p21.3, 12q15-24.1, 13q12-31, and 14q11.2/14q32.1-32.3. Marker analysis was performed in two Caucasian populations: (i) 192 unrelated German children with atopic dermatitis and 59 non-atopic children from a German birth cohort study (MAS'90), parental DNA was tested in 77 of 192 children with atopic dermatitis; (ii) 40 Swedish families with at least one family member with atopic dermatitis selected from the International Study of Asthma and Allergy in Children. Evidence for linkage and allelic association for atopic dermatitis was observed for markers on chromosome 13q12-14 and 5q31-33.

Early exposure to house-dust mite and cat allergens and development of childhood asthma: a cohort study. Multicentre Allergy Study Group

BACKGROUND

In a prospective birth-cohort study, we assessed the relevance of mite and cat allergen exposure for the development of childhood asthma up to age 7 years.

METHODS

Of 1314 newborn infants enrolled in five German cities in 1990, follow-up data at age 7 years were available for 939 children. Assessments included repeated measurement of specific IgE to food and inhalant allergens, measurement of indoor allergen exposure at 6 months, 18 months, and 3 years of age, and yearly interviews by a paediatrician. At age 7 years, pulmonary function was tested and bronchial hyper-responsiveness was measured in 645 children.

FINDINGS

At age 7, the prevalence of wheezing in the past 12 months was 10.0% (94 of 938), and 6.1% (57 of 939) parents reported a doctor's diagnosis of asthma in their children. Sensitisation to indoor allergens was associated with asthma, wheeze, and increased bronchial responsiveness. However, no relation between early indoor allergen exposure and the prevalence of asthma, wheeze, and bronchial hyper-responsiveness was seen.

INTERPRETATION

Our data do not support the hypothesis that exposure to environmental allergens causes asthma in childhood, but rather that the induction of specific IgE responses and the development of childhood asthma are determined by independent factors.

[Asthmatic children's risk factors for emergency room visits, Brazil]

OBJECTIVES

To study a sample of asthmatic children to get to know how the disease is managed by caretakers and to identify predictive factors associated with attendance in emergency room for asthma.

METHODS

A cross-sectional study nested in a cohort was undertaken in the urban area of Pelotas, Southern Brazil. 981 children aged 4-5 years, who belong to the cohort of 1993, participated in this study.

RESULTS

The asthma prevalence in the children sample was 25.4%. Morbidity for asthma was quite high: 31% of the children were seen in emergency rooms in the last year, 57% attended medical clinics and 26% were hospitalized in the first 4 years of life. The crude analysis identified the following predictive factors for emergency room visits: low educational level (RO=4.1), low family income (RO=6. 5), 3 or more children sleeping in the same room (RO=2.2), severity of asthma attacks (RO=2.7), use of asthma medicines in the last year (RO=1.9) and hospitalizations due to asthma (RO=3.0). Multivariate analyses using logistic regression were used to adjust each variable for the effect of the remainder.

CONCLUSIONS

The asthma prevalence among preschool children in Pelotas is high, resulting therefore in high morbidity. The predictor factors for emergency room visits due to asthma found, after multivariate analysis, were mother's low educational level, severity of the asthma attacks and hospitalization.

Limited agreement between written and video asthma symptom questionnaires

The prevalence of asthma remains difficult to determine with precision with no absolute or "gold" standard for diagnosis. A recently developed video questionnaire for epidemiological studies with less reliance on understanding written questions provides another tool for determining prevalence and severity of asthma. This report from the International Study of Asthma and Allergies in Childhood (ISAAC) examines the agreement between the ISAAC video questionnaires on respiratory symptoms and reported asthma. Between December 1993 and April 1995, 4952 children aged 13-14 years in two Canadian communities completed sequentially the ISAAC written and video questionnaires at school. The agreement between responses to the two questionnaires for reported wheeze ever, current wheeze, wheeze on exercise, and nocturnal wheeze (the latter three questions relating to symptoms in the last 12 months), and to any combination of the latter three questions was examined in the full sample and in those reporting diagnosed asthma, using concordance and kappa coefficients as measures of agreement. The prevalences of wheeze ever, current wheeze, wheeze on exercise, and nocturnal wheeze were significantly lower based on responses to the video questionnaire compared with the written questionnaire in both regions in the full sample and in those labeled as having asthma. Although concordance between video and written questionnaires always exceeded 60% and often exceeded 70% for related questions, agreement measured by the kappa statistic for each question was only fair to moderate (kappa = 0.22-0.51). We conclude that the video questionnaire yields lower reported prevalence rates for asthma symptoms, and that there is limited agreement between responses to the two questionnaires that is not explained by issues of language, culture, or literacy.

Symptoms suggestive of atopic rhinitis in children aged 6-9 years and the indoor environment

BACKGROUND

We aimed to investigate the influence of indoor factors on the prevalence of symptoms suggestive of atopic rhinitis in children aged 6-9 years in Upper Austria.

METHODS

We analyzed the results from an extended ISAAC (International Study of Asthma and Allergies in Childhood) questionnaire, answered by the parents, about indoor environment and symptoms strongly suggesting atopic rhinitis. This was defined as having reported a running, obstructed, or itchy nose apart from having a cold in the last year. The overall response rate was 93.4%. After excluding 6,016 children (17.1%) with changed indoor environment (due to allergies in the family), we analyzed the remaining subsample of 18,606 questionnaires.

RESULTS

The following factors were associated with an increased risk: mother's smoking during pregnancy and/or during time of breast-feeding (OR 1.28; CI 1.07-1.52), synthetic bedding (OR 1.21; CI 1.09-1.36), dampness/mold at home (OR 1.51; CI 1.31-1.74), central heating with gas (OR 1.75; CI 1.06-2.87), and space heating (OR 1.66; CI 1.01-2.98). Cooking with wood (OR 0.62; CI 0.46-0.84) was negatively associated with symptoms.

CONCLUSIONS

The indoor environment plays a role in the symptoms of atopic rhinitis in children. However, the population-attributable risks were not particularly high; they were between -2.7% and 9% for the various exposures considered in this study.

Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.

Genomic approaches to understanding asthma

Asthma is the most common chronic childhood disease in developed nations, and it is a complex disease that has high social and economic costs. Asthma and its associated intermediate phenotypes are under a substantial degree of genetic control. The genetic aetiology of asthma offers a means of better understanding its pathogenesis and, thus, improving preventive strategies, diagnostic tools, and therapies. Considerable effort and expense have been expended in attempts to detect genetic loci contributing to asthma susceptibility, and extensive candidate gene studies and a number of whole-genome screens have been undertaken. This article reviews the current state of knowledge of the genetics of asthma, with a focus on genomic approaches to understanding allergic diseases.

Validation of the ISAAC video questionnaire (AVQ3.0) in adolescents from a mixed ethnic background

BACKGROUND

The International Study of Asthma and Allergies in Childhood (ISAAC) has developed an international version of the asthma video questionnaire (AVQ3.0) to measure asthma prevalence. This questionnaire has not been validated in adolescents from a mixed ethnic background.

OBJECTIVE

The aims of this study were to compare the video questionnaire with a written questionnaire in the detection of airway hyperresponsiveness to hypertonic saline in a population of adolescents from a mixed ethnic background, and to establish the repeatability and psychometric properties of the asthma video questionnaire.

METHODS

The study was conducted in four secondary schools in Sydney, an area with a high proportion of people from a non-English speaking background. Four hundred and seventy-five students from schools 1 and 2 completed the video questionnaire and a subgroup of these students (n = 170) completed the written questionnaire and a hypertonic saline inhalation challenge. Reproducibility of the questionnaire was evaluated by administering the questionnaire to a subsample of students 2 weeks later. The psychometric properties of the video questionnaire were examined in 852 students at two other schools (schools 3 and 4).

RESULTS

One hundred and sixty-nine students aged 13.5 (sd 1.3) years completed both written and video questionnaires, and the hypertonic saline challenge. The students had widely different cultural backgrounds including Asian, South Pacific, Middle Eastern, European and African countries. There was good agreement between the questionnaires for wheeze (kappa 0.42). Questions on the video questionnaire concerning wheezing had good sensitivity (90%) and specificity (68%) for airway hyperresponsiveness to hypertonic saline. The video questionnaire was reproducible (kappa 0.82), had good internal consistency (Cronbach's alpha 0.81) and each question pertained to a single construct explaining 58% of the variance in total score.

CONCLUSION

This study has validated the international version of the ISAAC video questionnaire against airway hyperresponsiveness to hypertonic saline in adolescents from a mixed ethnic background, and identified that the questionnaire has good psychometric properties. The ISAAC video has proved to be a valuable tool for the assessment of asthma prevalence in populations of ethnic diversity.

Prevalence of asthma, allergic rhinitis, and eczema in 13- to 14-year-old children in Kuwait: an ISAAC study. International Study of Asthma and Allergies in Childhood

OBJECTIVES

To determine the prevalence of asthma and allergic diseases in 13 to 14 years old children in Kuwait.

DESIGN

Supervised self-administered written and video questionnaires of the international study of asthma and allergies in childhood (ISAAC).

SUBJECTS

Students at third and fourth years from 40 intermediate level schools chosen randomly from across Kuwait.

RESULTS

3,110 students were surveyed. The prevalence rates (95% CI) in the written questionnaire for wheeze ever, current wheeze (within the last 12 months), and physician diagnosis of asthma are 25.9% (24.5 to 27.4), 16.1% (15.8 to 17.4), and 16.8% (15.5 to 18.1) respectively. The prevalence rates (95% CI) for symptoms of allergic rhinitis (AR) ever, current symptoms of allergic rhinitis (AR), and diagnosis of AR are 43.9% (42.2 to 45.6), 30.7% (29.1 to 32.4) and 17.1% (14.8 to 18.4) respectively. The prevalence rates (95% CI) for itchy rash ever, current itchy rash, and diagnosis of eczema are 17.5% (16.2 to 18.8), 12.6% (11.4 to 13.8), and 11.3% (10.2 to 12.4) respectively. The prevalence of wheeze ever, wheeze during the last year, and physician diagnosis of asthma are higher in males compared with females, P < .01. In multiple logistic regression: male gender (OR 1.6, 95% CI, 1.3 to 2.0) and diagnosis of AR (OR 1.7, 95% CI, 1.4 to 2.2) were associated with the physician diagnosis of asthma even after controlling for symptoms of asthma.

CONCLUSION

This is the first study on the prevalence of allergic diseases in Kuwait and it shows that children in Kuwait have a moderate prevalence of asthma, AR, and eczema compared with other countries where the ISAAC study is done. The prevalence of asthma is higher in boys compared with girls.

Effects of birthweight and oxygen supplementation on lung function in late childhood in children of very low birth weight

Impaired respiratory function has been found frequently in ex-premature children, but it is unclear which specific factors influence this impairment the most. The aim of this study was to determine the importance of the contributions of birth weight, gestational age, neonatal respiratory disease, and its treatment on subsequent childhood lung function at age 11 years in a cohort of children of very low birth weight (VLBW; </=1,500 g). Detailed clinical histories were recorded, and lung function was measured in 60% (102 children) of surviving VLBW infants born 1981/1982, and compared with 82 matched control children (birth weight >2,000 g) of similar age. VLBW children were shorter and lighter than controls (P < 0.0001) at 11 years of age, and had reduced expiratory flows (P < 0.00001) and forced vital capacities (P < 0.001). The residual volume to total lung capacity ratio (RV/TLC ratio) was increased (P < 0.00001), while total lung capacity (TLC) remained unchanged. Those with bronchopulmonary dysplasia (BPD) had the lowest mean expiratory flows. Males had lower expiratory flows than females. On univariate analysis, gestational age by itself accounted for 8.8% of the explained variance in FEV(1) at 11 years of age, but birth weight accounted for 16% on its own; both together accounted for a further 0.2% (16.2%), suggesting that the latter was the dominant factor. On multivariate analysis, the contribution of birth weight and gestational age was small, and the best predictors at 11 years of age, which together explained 43.4% of the total variance in FEV(1), were log days of supplemental oxygen (9.6%) and a reported history of asthma (10.8%). For FEF(25-75), these predictors explained 7.2% and 13.4%, respectively, of the total explained variance of 40.6%. The relation between neonatal oxygen supplementation and childhood FEV(1) was such that up to 20 days of supplemental oxygen had little effect on subsequent FEV(1) at 11 years of age, but each additional week of supplemental oxygen after that time was associated with a progressive reduction in FEV(1) of 3%. These data confirm the significant role of supplemental oxygen in the neonatal period and a history of asthma on the subsequent reduction of expiratory flows in VLBW children. Birth weight was a more important prenatal factor than gestational age, but both were of lesser predictive significance than either supplemental oxygen or a reported history of asthma.

Asthma prevalence in schoolchildren in a city in north-east Brazil

Asthma is a disease of increasing prevalence all over the world. The objectives of this study were to describe the prevalence of asthma and aspects of its morbidity in schoolchildren in Recife, and to evaluate the relationship between maternal schooling and asthma prevalence during 1994-1995. This is part of an international, multicentre research project, the International Study of Asthma and Allergies in Childhood (ISAAC). In a cross-sectional design, a probabilistic sample of 1410 children of 6 and 7 years of age and 3086 teenagers of 13 and 14 years were studied by questionnaire. The yearly prevalences of asthma symptoms in these two groups were 27.2% (CI 95%: 24.9-29.5%) and 18.1% (CI 95%: 16.4-19.8%), respectively; the cumulative prevalences of diagnosed asthma were 20.4% (CI 95%: 17.8-23.0%) and 19.7% (CI 95%: 19.4-22.2%), respectively, and the prevalences of asthma according to severity were: mild--68.9% and 81.3%, moderate--24.2% and 13.5%, severe--6.80% and 5.3%. During the previous year, the frequencies of crises with sleeping disorder were 23.2% and 13.0% and of disorder that limited speech 9.6% and 4.8%, respectively. There was a significant relationship between maternal education and cumulative prevalence of symptoms in both groups. It is concluded that asthma is a common disease which causes much morbidity in schoolchildren in Recife. The results suggest a relationship between low maternal education and a greater prevalence of asthma.

Urbanization and the risk of asthma among schoolchildren in the Palestinian Authority

The aim of the present survey was to compare the prevalence of symptoms suggestive of asthma in boys and girls aged 6-7 and 13-14 years in a rural and an urban area in the West Bank. For this purpose, the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was issued to 970 schoolchildren in the two regions. The response rate was 92.2%. The prevalences of ever wheezing in the urban and rural areas were 16.4% and 12.0%, respectively (p < 0.05); the 12-month prevalences of wheezing were 10.5% and 5.5%, respectively (p < 0.05); the prevalences of more severe wheeze were 4.5% and 1.7%, respectively (p < 0.05); and prevalences of diagnosed asthma were 4.2% and 2.8%, respectively (p = NS). When controlling for age by stratification, the significant association between prevalence rates and place of residence persisted in the 13-14-year age group. These results also show that the prevalence of asthma among Palestinian children is moderately high in comparison with that reported from developing countries, but lower than those reported from Western countries. This survey, the first epidemiological survey on asthma in the West Bank, demonstrates a marked difference between urban and rural areas. The findings emphasize the need for further study of the environmental determinants of the disease among Palestinian children.

Asthma and Latino cultures: different prevalence reported among groups sharing the same environment

OBJECTIVES

This 1999 study measured asthma prevalence among Latinos of different cultural traditions who live on the same streets and in the same buildings.

METHODS

Health promoters from El Puente in North Brooklyn, New York City, surveyed 3015 people in 946 households, asking standard asthma prevalence questions.

RESULTS

Some 46% of households identified themselves as Dominican, 42% as Puerto Rican, 6% as other Latino, and 6% as other. Reported asthma period prevalence was 5.3% (93 of 1749) among Dominicans and other Latinos, compared with 13.2% (147 of 1115) among Puerto Ricans (odds ratio = 0.37; 95% confidence interval = 0.28, 0.49), a difference not explained by location (cluster or building), household size, use of home remedies, educational attainment, or country where education was completed. Differences were least detectable among 13- to 24-year-olds of both sexes and sharpest among women aged 45 years and older and girls from birth to 12 years.

CONCLUSIONS

Further research on gene-environment interactions is needed among Puerto Ricans and Dominicans, but asthma's associations with low income and unhealthy environment, which more recent immigrants seem better able to withstand, should not be overlooked.

The wheezing schoolchild--an undiagnosed asthmatic. A follow-up of children with parentally reported episodes of wheeze without diagnosed asthma

OBJECTIVE

To examine children aged 7-15 years with parentally reported episodes of wheeze in order to estimate the proportion of undiagnosed asthmatics in this group.

DESIGN

A cross-sectional study with clinical examination of subgroups.

SETTING

All children (n = 832) aged 7-15 years in the municipality of Odda.

SUBJECT

Based on completed questionnaires, the children were selected to one of four groups: Children with wheeze but no asthma (wheeze group); children with current asthma (asthma group); children with past asthma (past asthma group); and children with neither asthma nor wheeze (control group).

MAIN OUTCOME MEASURES

Parental reports of episodes of wheeze, assessment of skin prick test sensitivity, measures of lung function and exercise-induced bronchoconstriction (EIB).

RESULTS

In the wheeze group, 3 (7.5%) of 40 children were diagnosed with asthma in the 18-month period between the questionnaire survey and the examination, while 4 (10%) other children had EIB. Another 8 children (20%) reported 3 episodes of wheeze or more, and at least 1 episode during the 12-month period before the clinical examination. Classifying these children as asthmatics would give a proportion of 37.5% with undiagnosed asthma in the wheeze group, and the prevalence of current asthma among children aged 7-15 would rise from 2.9% based on a questionnaire survey to 4.9%. CONCLOSIONS: Using a wide definition of asthma, this study suggests that a large proportion of Norwegian children with wheeze actually have asthma.

International patterns of tuberculosis and the prevalence of symptoms of asthma, rhinitis, and eczema

BACKGROUND

An ecological analysis was conducted of the relationship between tuberculosis notification rates and the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema in 85 centres from 23 countries in which standardised data are available. These essentially comprised countries in Europe as well as the USA, Canada, Australia, and New Zealand.

METHODS

Tuberculosis notification rates were obtained from the World Health Organization. Data on the prevalence of symptoms of asthma, rhinitis, and eczema in 235 477 children aged 13-14 years were based on the responses to the written and video questionnaires from the International Study of Asthma and Allergies in Childhood (ISAAC). The analysis was adjusted for gross national product (GNP) as an estimate of the level of affluence.

RESULTS

Tuberculosis notification rates were significantly inversely associated with the lifetime prevalence of wheeze and asthma and the 12 month period prevalence of wheeze at rest as assessed by the video questionnaire. An increase in the tuberculosis notification rates of 25 per 100 000 was associated with an absolute decrease in the prevalence of wheeze ever of 4.7%. Symptoms of allergic rhinoconjunctivitis in the past 12 months were inversely associated with tuberculosis notification rates, but there were no other significant associations with other ISAAC questions on allergic rhinoconjunctivitis or atopic eczema.

CONCLUSIONS

These findings are consistent with recent experimental evidence which suggests that exposure to Mycobacterium tuberculosis may reduce the risk of developing asthma.

Medication use among children with asthma in East Harlem

PURPOSE

To examine daily use of antiinflammatory medication among children with asthma in East Harlem, where hospitalization rates for asthma are among the highest in the United States.

METHODS

We analyzed parent/guardian reports of medications used by children with current asthma (defined as physician diagnosis and wheezing during the previous 12 months) identified from a cross-sectional survey conducted in 2 elementary schools.

RESULTS

From an overall sample of 1319 children, 298 with current asthma were included in this analysis. Most of those with asthma were Puerto Rican (136 [46%]) or black (98 [33%]), 168 (57%) were boys, and the median age was 8 years old. Overall, 65 (22%) were using antiinflammatory medication on a daily basis. A subgroup of 107 children with asthma had been hospitalized during the previous 12 months or had used beta(2)-agonist on a daily basis, suggesting persistent or severe asthma. Of these 107 children, 42 (39%) were taking antiinflammatory medication on a daily basis. Multivariate analysis of these 107 children revealed that daily use of antiinflammatory medication was associated with using a spacer tube (adjusted odds ratio [AOR]: 3. 08; 95% confidence interval [CI]: 1.27,7.47) and having seen a physician in the past 6 months (AOR: 3.46; CI: 1.01,11.9). Compared with Puerto Ricans, blacks (AOR:.32; CI:.12,.89) or children of other races/ethnicities (AOR:.27; CI:.09,.85) were less likely to use antiinflammatory medication on a daily basis.

CONCLUSION

Daily use of antiinflammatory medication for children with persistent or severe asthma in East Harlem was underused. Differences in access to care may explain some findings; however, reasons for ethnic differences in use remain unclear. Both community interventions and additional provider education are needed.

Relative scarcity of asthma and atopy among rural adolescents raised on a farm

We determined the prevalence of markers of atopy and asthma among 1, 199 rural secondary school students ages 12 to 19 yr. Subjects identified as having been raised on a farm and half as many subjects without regular exposure to a farming environment from the same school class completed a respiratory symptom questionnaire and underwent allergy skin tests and a methacholine bronchoprovocation test. Current wheeze, airways hyperresponsiveness (AHR), and skin test positivity to inhaled allergens were all significantly less common among adolescents raised on the farm and these differences were especially pronounced in girls. After adjusting for gender and current smoking, the odds ratios for being raised on a farm were: 0. 70 (95% CI 0.52 to 0.95) for current wheeze; 0.59 (95% CI 0.37 to 0. 95) for asthma, defined as the concomitant occurrence of wheeze and AHR; and 0.58 (95% CI 0.46 to 0.75) for atopy defined as a positive reaction to any one of 24 common inhaled allergens. These associations were also not significantly altered by adjusting for the difference in the number of siblings.

What do parents of wheezy children understand by "wheeze"?

BACKGROUND

Reported wheeze is the cornerstone of asthma diagnosis.

AIMS

To determine what parents understand by wheeze.

METHODS

Two studies were undertaken: (1) Parents of clinic attendees with reported wheeze (n=160) were asked by questionnaire what they understood by "wheeze" and how they knew their child was wheezy. Responses were compared to definitions of wheeze in 12 epidemiology studies and their response options. (2) The extent of agreement of parents' reports (n=139) of acute wheezing in their children and clinicians' findings of "wheeze" and "asthma" was examined.

RESULTS

(1) "Sound" and "difficulty in breathing" were perceived central to "wheeze". "What you hear" was not selected by 23% (95% confidence interval (CI) 16-30%). "Whistling" was mentioned by 11% (CI 6-15%) but featured in 11 of 12 epidemiology questionnaires. (2) There was les than 50% agreement between parents' and clinicians' reports of wheeze and asthma.

CONCLUSIONS

Conceptual understandings of "wheeze" for parents of children with reported wheeze are different from epidemiology definitions. Parents' reports of acute wheeze and clinicians' findings also differ.

Exposure and allergic sensitization to cockroach allergen in East Germany

BACKGROUND

Some studies suggest that the prevalence of sensitization to cockroach allergens may be higher in the United States than in Europe, but there are no comparable data from population-based studies.

OBJECTIVES

To determine the prevalence of allergic sensitization to German cockroach (GCR) in German schoolchildren and to assess its clinical relevance; and to determine the exposure to the major GCR allergen Bla g 2 in non-selected homes and nurseries.

METHODS

The prevalence of allergic sensitization to GCR and other allergens was determined by measurement of specific IgE and skin-prick tests in a cross-sectional study of 2993 children aged 5-11 years in Dresden, Germany. The prevalence of atopic disease was determined by questionnaire, and pulmonary function and bronchial hyperresponsiveness to hypertonic saline were measured. Bla g 2 exposure was determined on floors of 187 kitchens and 47 nurseries by a commercial sandwich ELISA.

RESULTS

One hundred and twenty-seven (4.2%) of the children had specific IgE (> 0.7 kU/L) against GCR. Among children with current wheeze, 8.4% were GCR-sensitized. Compared to data from the United States, the prevalence of sensitization to cockroach was similar in children without asthma (3.9%), but less frequent in asthmatic children from Dresden (6.1%). After adjustment for positive reactions to other allergens (SX1 test) no significant impact of GCR sensitization on wheeze or other symptoms and diagnoses was found. Bla g 2 was detected in 29% of the kitchens and 43% of the nurseries. None of these sites had exposure levels above the proposed threshold for causing disease of 80 ng/g dust.

CONCLUSION

The data suggest that allergic sensitization to GCR is less frequent in asthmatics from Dresden, Germany than in US cities. The data indicate that GCR sensitization is not an independent risk factor for asthma and other atopic diseases in 5-11-year-olds from this city.

Repeatability of the ISAAC video questionnaire and its accuracy against a clinical diagnosis of asthma

The objective of the study was to evaluate the performance of the International Study of Asthma and Allergies in Childhood (ISAAC) video questionnaire in terms of repeatability and accuracy against a clinical diagnosis of asthma achieved according to the National Heart, Lung and Blood Institute (NHLBI) algorithm. Two hundred and forty-one subjects, aged 13-14 years from two secondary schools in Rome, Italy, were enrolled. Video and written ISAAC questionnaires were completed twice, 3 months apart, by 194 and 190 adolescents, respectively. Two months later, 106 subjects were visited by two physicians blinded to the results of questionnaires. Sixteen subjects were classified as having clinical asthma (CA) at the clinical visit, and eight of them as having clinical active asthma (CAA) on the basis of at least one positive outcome of the NHLBI algorithm. The repeatability of video questionnaire was similar to that of the written questionnaire for items on exercise wheeze and nocturnal cough and, to a lesser degree, for items concerning any wheeze in the past. The video questionnaire showed a worse performance than the written questionnaire for items on asthma attack: K-value (95% CL) = 0.59 (0.37-0.80) for video scene no. 5 and K-value (95% CL) = 0.86 (0.74-0.98) for written question no. 6. The overall accuracy of the video questionnaire, estimated as a positive answer to any video scene, was lower in terms of sensitivity than that of any written question when CA was used as a gold standard (0.50 vs. 0.81, P=0.025) and increased with respect to CAA (0.75 vs. 0.87, P = 0.317). The specificity of any video scene was better than that of any written question, independently from the gold standard used. In conclusion, the video questionnaire showed a fairly good accuracy, although slightly lower than that of the written questionnaire and provided sufficiently reliable results. However, samples of subjects from different geographic areas and cultures should be studied in order to conclusively define the performance of the ISAAC video questionnaire.

Use of diclofenac in children with asthma

This study investigated the effect of diclofenac on the lung function of 70 children aged 6-15 years with a diagnosis of asthma, recruited from a hospital respiratory clinic. Peak flow and a forced expiratory flow-volume loop were measured and the patients were then given 1-1.5 mg.kg-1 effervescent diclofenac orally. Spirometry was repeated at 10, 20 and 30 min, a 15% decrease in results being considered a significant reduction in lung function. No patient demonstrated a consistent reduction in lung function of > 15% during the study and there were no reports of wheezing or increased bronchodilator use after completion of the spirometry. In conclusion, we studied a group of genuine asthmatics and found no clinically significant incidence of bronchospasm with the use of a single therapeutic dose of diclofenac.

Local road traffic activity and the prevalence, severity, and persistence of wheeze in school children: combined cross sectional and longitudinal study

OBJECTIVES

To investigate the relation between local road traffic activity and the occurrence, severity, and persistence of wheeze in children.

METHODS

Data on wheeze and asthma were collected in a cross sectional questionnaire survey of 22,968 primary school children (age 4-11) and 27,826 secondary school children (age 11-16) in the Nottingham area. Direct measures of road traffic flow were made in the locality of each school and combined with Local Authority traffic data for major roads to estimate local traffic activity in vehicle metres/day/km2. Assessment of the effects of potential confounders was performed in nested case-control groups of 6576 primary and 5936 secondary children. Data on frequency of wheeze were collected for the cases to study disease severity. Longitudinal data on a historical cohort of 883 children who reported wheeze when aged 4-11 in 1988 were used to study the persistence of wheeze into adolescence.

RESULTS

Unadjusted prevalence of wheeze in the past year within schools varied widely but was not associated with traffic activity in the school locality (weighted regression coefficient beta = -0.01, p = 0.93 for primary schools, beta = -0.18, p = 0.26 for secondary schools). The risk of wheeze in individual primary school children was not associated with traffic activity analysed as a continuous variable, although there was some suggestion of a weak, non-linear plateau effect. Similar effects were found for diagnosed asthma and recent cough. There was no evidence of any relation between traffic activity and risk of wheeze in secondary school children. There were positive but non-significant dose related effects of traffic activity on wheeze severity in primary and secondary children and on persistence of wheeze in the longitudinal cohort.

CONCLUSIONS

Traffic activity in the school locality is not a major determinant of wheeze in children.

The relation between infant indoor environment and subsequent asthma

Our aim was to examine the contribution of an infant's indoor environment to childhood asthma using prospective data. We conducted a cross-sectional asthma survey in 1995 on 92% (6,378/6,911) of 7-year-olds in Tasmania, Australia. We linked these data with data collected in 1988 as part of the Tasmanian Infant Health Survey, which was designed to investigate sudden infant death. We were able to match 863 records out of the 1,111 in the 1988 survey and the 6,378 in the 1995 survey. The former group was interviewed at home at 1 month of age. In homes where at least one adult smoked in 1988, reported infant exposure to smoking in the same room in 1988 was associated with increased asthma by 1995 (relative risk = 1.52; 95% confidence interval = 1.01-2.29) after adjustment for confounders. The associations between infant exposure to environmental tobacco smoke and asthma were not consistent, however. Gas heater use in 1988 was associated with asthma (relative risk = 1.92; 95% confidence interval = 1.33-2.76). Markers of aeroallergen exposure at 1 month of age were not materially associated with asthma or wheeze. In some settings, air circulation practice with regard to bedroom door closure appeared important. Poor indoor air quality may play an important role in the development of childhood asthma.