International Study of Asthma and Allergies in Childhood (ISAAC): validation of the written questionnaire (eczema component) and prevalence of atopic eczema among Brazilian children.

Although Hanifin and Rajka's criteria have been used for the diagnosis of atopic eczema (AE), there is no instrument destined for epidemiological studies on AE that actually uses them. Written questionnaires (WQ) have generally been used, but when translated into another language they must be validated. The Intemational Study of Asthma and Allergies in Childhood (ISAAC) WQ was previously validated in a comprehensive study, but its validation in Brazil had not been done. Our objective was to validate the eczema component of the self-applicable ISAAC's WQ following its translation into Portuguese. The group of 10 pediatricians and 10 pediatric allergologists graded the questions from 0 to 2 and established the maximum score for each question. The WQ was answered by parents or guardians of children with atopic dermatitis (AE), aged 6-7 years (n = 23) and of non-AE control children of the same age (n = 46) as well as by AE (n = 24) and non-AE (n = 48) adolescents, aged 13-14 years. In order to evaluate the reproducibility of the ISAAC WQ, half of these individuals answered the same questionnaire after 2 to 4 weeks. The maximum possible global scores were 13 for the children aged 6-7 years and 11 for the adolescents, and the cutoff level for both groups was 3. In both age periods the WQ was reproducible (Kappa and McNemar tests) in a significant way (6-7 years, Kw = 0.79; 13-14 years, Kw = 0.73). The prevalence of AE, using the validated WQ, was then studied. The WQ was applied to the parents of 3,005 children aged 6-7 years and to 3008 children aged 13-14 years. Response rates were 72% and 94% for the 6-7-year-old children and the 13-14-year-old children, respectively. There was a slight predominance of male children in the studied population. In the group of the 6-7-year-old children, the cumulative prevalence of AE was 13.2% for boys and for girls; in the group of the 13-14-year-old children, it was 12.5% and 15.4%, respectively. AE severity was similar for both age groups. Using the criteria of global cutoff score, in the group of the 6-7-year-old children, the prevalence of AE was 12.6% for boys and 13.8 for girls; in the group of the 13-14-year-old children, it was 11.7% and 12.4%, respectively. There were no significant differences between them. In conclusion, the AE component of the ISAAC WQ proved to be reproducible, adequate, and able to discriminate between AE and control children. A significant concordance was observed between the criteria utilized in this study (ISAAC x global cutoff score).     

International Study of Asthma and Allergies in Childhood (ISAAC): prevalence of asthma and asthma-related symptoms among Brazilian schoolchildren.

We have studied the prevalence of asthma and its symptoms using a standard written questionnaire (WQ) designed for the International Study of Asthma and Allergies in Children (ISAAC). The WQ (questions 1 through 8 related to asthma) was applied to 13,604 children aged 6-7 years from six Brazilian cities: Porto Alegre (South, N = 2,976), Curitiba (South, N = 1,664), S?o Paulo (Southeast, N = 3,005), Uberlandia (Southeast, N = 3,002), Itabira (Southeast, N = 1,551) and Recife (Northeast, N = 1,406). At the age of 13-14 years the WQ was applied to 20,554 schoolchildren living in Porto Alegre (South, N = 3,198), Curitiba (South, N = 3,008), S?o Paulo (Southeast, N = 3,008), Uberlandia (Southeast, N = 3,001), Itabira (Southeast, N = 2,134), Salvador (Northeast, N = 3,119) and Recife (Northeast, N = 3,086). The parents of the younger children answered the WQ, whereas the adolescents answered the questionnaire themselves. The response rates were 72% and 93% for the 6-7-year-old children and for the 13-14-year-old children, respectively. There was a slight predominance of male children in the population studied. In the group of 6-7-year-olds, the prevalence of physician diagnosed asthma was 7.3% for boys and 4.9% for girls: in the group of 13-14-year-olds the rates were 9.8% and 10.2%, respectively. Asthma severity was similar for both age groups, and wheezing following exercise was more frequent among the adolescents. In keeping with studies from other parts of the world, comparison between reported symptoms and diagnosed asthma revealed a significantly lower frequency of diagnosed asthma, suggesting that in the study population, asthma is underdiagnosed.     

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.     

The International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three: A global synthesis

This ISAAC Phase Three synthesis provides summarised information on the main findings of the study, regional tables and figures related to the prevalence and severity of current symptoms of asthma, rhinoconjunctivitis and eczema in the main regions of the world. The large number of surveyed children (≈1,200,000), the large number of centres (233) and countries (98) that participated in ISAAC Phase Three makes this study the most comprehensive survey of these diseases ever undertaken. Globally, the prevalence for current asthma, rhinoconjunctivitis and eczema in the 13–14-year age group was 14.1%, 14.6% and 7.3%, respectively. In the 6–7-year age group the prevalence for current asthma, rhinoconjunctivitis and eczema was 11.7%, 8.5% and 7.9%, respectively. The study shows a wide variability in the prevalence and severity of asthma, rhinoconjunctivitis and eczema which occurs not just between regions and countries but between centres in the same country and centres in the same city. This study definitively establishes that the prevalence of those diseases can be very high in non-affluent centres with low socioeconomic conditions. The large variability also suggests a crucial role of local environment characteristics to determine the differences in prevalence between one place and another. Thus, ISAAC Phase Three has provided a large body of epidemiological information on asthma, rhinoconjunctivitis and eczema in childhood from contrasting environments which is expected to yield new clues about the aetiology of those conditions and reasons for their marked global variability.     

Phase II of the International Study of Asthma and Allergies in Childhood (ISAAC II): rationale and methods.

International comparative studies, investigating whether disease incidence or prevalence rates differ between populations and, if so, which factors explain the observed differences, have made important contributions to the understanding of disease aetiology in many areas. In Phase I of the International Study of Asthma and Allergies in Childhood (ISAAC), the prevalence rates of symptoms of asthma, allergic rhinitis and atopic eczema in 13-14-yr-olds, assessed by standardised questionnaires, were found to differ >20-fold between the 155 study centres around the world. Phase II of ISAAC aims to identify determinants of these differences by studying informative populations. A detailed study protocol was developed for use in community-based random samples of children aged 9-11 yrs. The study modules include standardised questionnaires with detailed questions on the occurrence and severity of symptoms of asthma, allergic rhinitis and atopic eczema, their clinical management, and a broad range of previous and current exposure conditions. In addition, standardised protocols were applied for examination of flexural dermatitis, skin-prick testing, bronchial challenge with hypertonic saline, blood sampling for immunoglobulin E analyses and genotyping, and dust sampling for assessment of indoor exposures to allergens and endotoxin. To date, ISAAC II field work had been completed or started in 30 study centres in 22 countries. The majority of centres are in countries that participated in International Study of Asthma and Allergies in Childhood Phase I and reflect almost the full range of the observed variability in Phase I prevalence rates.     

Prevalence of atopic eczema and related symptoms in Brazilian schoolchildren: results from the International Study of Asthma and Allergies in Childhood (ISAAC) phase 3.

BACKGROUND: International comparisons of the prevalence of atopic eczema and related symptoms are scarce. The standardized protocol of the International Study of Asthma and Allergies in Childhood (ISAAC) facilitates investigation of prevalence all over the world. OBJECTIVE: To apply the ISAAC written questionnaire to evaluate the prevalence of atopic eczema and related symptoms among 6-7 year-old children and 13-14 year-old adolescents living in 20 Brazilian cities. METHODS: The ISAAC written questionnaire was filled in by 23,422 children aged 6-7 years and 58,144 adolescents aged 13-14 years living in 2 population centers in the north, 8 in the northeast, 1 in the midwest, 5 in the southeast, and 5 in the south. RESULTS: The prevalence of flexural eczema (itchy rash ever in characteristic places in the last 12 months) ranged from 5.3% to 13.0% for children and was lower among the adolescents (range, 3.4%-7.9%). Among children, the highest rates were observed in population centers in the northeast, mainly along the coast. Among adolescents the highest rates were observed in the north and northeast, mainly in Natal, Aracaju, and Vitória da Conquista. The northeastern countryside had higher prevalence rates of severe eczema (kept awake at night by this itchy rash in the last 12 months) in comparison to northeastern coastal centers. There was a significant correlation between the prevalence of flexural eczema and severe eczema for both age groups, separately (6-7 year-olds, prho= 0.756, P<.004; 13-14 year-olds, rho=0.874, P<.0001) or grouped (6-7 plus 13-14 years-olds, rho=0.696, P<.0001). CONCLUSION: The prevalence of eczema and related symptoms is variable in Brazil, where the highest prevalence is found in the north and northeast; on the other hand, a higher prevalence of severe eczema was observed in Brazilian centers in the south.     

Prevalence of asthma among Qatari schoolchildren: International Study of Asthma and Allergies in Childhood, Qatar

The aim of the present study is to determine the prevalence of asthma and allergic diseases among schoolchildren aged 6-14 years in the State of Qatar, based on a questionnaire designed by the International Study of Asthma and Allergy in Childhood (ISAAC). A cross-sectional study of 3,283 school children living in both urban and rural areas (average age, 9.03 +/- 1.99 years; 52.3% boys and 47.7% girls) was conducted between February 2003-February 2004. The population sample had a high prevalence of diagnosed asthma (19.8%), allergic rhinitis (30.5%), eczema (22.5%), and chest infection (11.9%). The frequency of asthma, allergic rhinitis, and eczema among parents reflected the same pattern as seen in their children. Overall, males had more asthma, allergic rhinitis, and chest infections than females. In general, the prevalence rate of asthma and allergic rhinitis decreased with age. The prevalence rate of asthma was significantly higher in mothers (11.8%) than in fathers (9.0%), but the frequency of allergic rhinitis symptoms was comparable (mothers, 18.5%; fathers, 17.5%). The prevalence rate of asthma (19.8%) in Qatari schoolchildren is very close to that in the neighboring Gulf country, Oman (20.7%), and higher than in some developing countries. Genetic factors related to the high rates of consanguinity may play an important role in the high prevalence rates noted in the Qatari population, but changes in lifestyle and environmental factors cannot be discounted as possible causes of the high prevalence noted in this study.     

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.     

Comparison of asthma prevalence in the ISAAC and the ECRHS. ISAAC Steering Committee and the European Community Respiratory Health Survey. International Study of Asthma and Allergies in Childhood.

International and regional prevalence comparisons are required to test and generate hypotheses regarding the causes of increasing asthma prevalence in various age groups worldwide. The International Study of Asthma and Allergies in Childhood (ISAAC) is the first such study in children and the European Community Respiratory Health Survey (ECRHS) is the first such study in adults. Therefore, a comparison of the findings of these two surveys was conducted, for the 17 countries in which both surveys were undertaken. There was a strong correlation between the ISAAC and ECRHS prevalence data, with 64% of the variation at the country level, and 74% of the variation at the centre level, in the prevalence of "wheeze in the last 12 months" in the ECRHS phase I data being explained by the variation in the ISAAC phase I data. There was also generally good agreement in the international patterns observed in the two surveys for self-reported asthma (74% of country level and 36% of centre level variation explained), self-reported asthma before age 14 yrs (64 and 26%), hay fever (61 and 73%) and eczema (41 and 50%). Thus although there were differences in the absolute levels of prevalence observed in the two surveys, there is good overall agreement between the International Study of Asthma and Allergies in Childhood and European Community Respiratory Health Survey study findings with regard to international prevalence patterns. These findings, therefore, add support to the validity of the two studies, which provide a new picture of global patterns of asthma prevalence from child- to adulthood, and identify some of the key phenomena which future research must address.     

Validity and Reproducibility of the Asthma Core International Study of Asthma and Allergies in Childhood (ISAAC) Written Questionnaire Obtained by Telephone Survey

Objective. To assess the reproducibility and validity of the International Study of Asthma and Allergies in Childhood (ISAAC) asthma written questionnaire (IAWQ) for 6- to 7-year-old children administered to their parents/caregivers through a telephone interview. Methods. Our study included 100 children selected from three health units in Rio de Janeiro, Brazil. In total, 50 asthmatic and 50 non-asthmatic children were evaluated; all participants were required to own a household telephone line. Initially, telephone interviews were conducted with the parents/caregivers using the IAWQ. After 2 weeks, parents/caregivers were invited to complete the IAWQ under supervision provided by the researchers. After fifteen days, the telephone interviews were repeated. The reproducibility between the two telephone interviews was assessed using kappa (κ) coefficients; the construct validity was assessed by comparing the answers obtained in the initial telephone interview in both groups according to the clinical diagnosis of asthma performed by a specialist using sensitivity and specificity coefficients. Results. Overall, data from 75 children (39 asthmatics) were analyzed, as 25 patients were excluded from the study (11 did not answer phone calls and the responding parents/caregivers for 14 patients were not the same in all study phases). Perfect agreement was observed for the indicator “wheezing in the last 12 months” (κ = 1), while substantial agreement was observed for the “wheezing with exercise,” “speech limited by wheezing,” and “asthma ever” indicators (κ range, 0.7–0.8). The sensitivity and specificity for “wheezing within the last 12 months” were 64.1% (95% confidence interval (CI), 47.2–78.8) and 88.9% (95% CI, 73.9–96.9), respectively. For the “asthma ever” indicator, the sensitivity and specificity were 87.2% (95% CI, 77.6–95.7) and 100% (95% CI, 90.3–1), respectively. Questionnaire specificity was high for all asthma severity indicators. Conclusions. The IAWQ for children aged 6–7 years adapted for telephone interviews showed good reproducibility and adequate validity with an ability to distinguish between asthmatic and non-asthmatic participants. Thus, this method could be utilized in epidemiological studies on childhood asthma in locations where telephone lines are available.     

Changes over time in the relationship between symptoms of asthma, rhinoconjunctivitis and eczema: A global perspective from the International Study of Asthma and Allergies in Childhood (ISAAC)

BACKGROUND: The International Study of Asthma and Allergies in Childhood (ISAAC) identified trends in the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema over a seven-year period. We hypothesised that environmental influences on the three diseases are different and therefore investigated the correlation over time between trends in the prevalence of these diseases and their combinations at centre and individual level. METHODS: Centre level analyses were correlations between time trends in the prevalence of symptoms. At an individual level, odds ratios were calculated for associations between symptoms between Phases One and Three. We also investigated potential effect modification in the younger versus older age group; male versus female; and by average Gross National Income per capita (GNI). RESULTS: Both phases were completed in 66 centres in 37 countries for the 6-7 year age group and in 106 centres in 56 countries for the 13-14 year age group. We found that the correlations in time trends were stronger for the older age group than the younger one. Between symptoms of diseases, correlations of time trends were the strongest for rhinoconjunctivitis with eczema and weakest for eczema with asthma. The relationship between the three diseases was generally consistent over the seven-year period, and there was little association found with average GNI. CONCLUSIONS: Despite some increase in the proportion of children with symptoms of asthma, rhinoconjunctivitis and eczema, the pattern between the three diseases has not changed much, suggesting that similar factors may be affecting them at a global level.     

Prevalence of Asthma and Other Childhood Allergies in Brazilian Schoolchildren

We determined the prevalence of asthma, rhinitis, and eczema among Brazilian children using the standardized protocol of the International Study on Asthma and Allergies in Childhood (ISAAC) to facilitate the comparison of our results with other studies using the ISAAC methodology. We conducted a cross-sectional study from June to October 1994 to determine the prevalence of asthma, rhinitis, and eczema in 5182 school children aged 7-8 years and 13-14 years residing in the Brazilian towns of Santa Maria and Itabira (iron-mining cities located in Minas Gerais). Parents completed questionnaires at their child's school in the presence of trained interviewers. The cumulative prevalence of doctor-diagnosed asthma was 4.6% for all ages with no significant difference between the age groups. In general, there was a higher prevalence of symptoms in the younger age group than the older. The prevalence of wheezing in the previous 12 months was 14.3% (7-8 years old) and 9.3% (13-14 years old) (p ≤ 0.01), of chronic cough in the previous 12 months was 25.6% (7-8 years old) and 22.1% (13-14 years old) (p ≤ 0.01), and of nighttime cough in the previous 12 months was 22.3% (7-8 years old) and 19.4% (13-14 years old) (p ≤ 0.05). Overall the prevalences of asthma and wheezing symptoms in the previous 12 months were higher for boys than girls (5.2% vs. 3.9% for asthma, p ≤ 0.01, and 13.2% vs. 10.6% for wheezing, p ≤ 0.01, respectively). These results suggest that asthma-related respiratory illnesses affect a substantial part of the childhood population in Itabira and Santa Maria, Minas Gerais. Some factors such as male gender and younger age may be associated with an increase risk for chronic respiratory symptoms. Prevalences of asthma and allergic diseases in these Brazilian cities on the basis of self-reporting of symptoms and of one's medical history may more accurately portray the true prevalence of asthma than the use of medical records.     

Assessing bronchial responsiveness to hypertonic saline using the stepwise protocol of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC II)

Measurement of bronchial responsiveness to hypertonic saline was applied in 22 study centers worldwide as part of Phase Two of the International Study of Asthma and Allergies in Childhood (ISAAC Phase Two). Because the amount of inhaled saline was difficult to standardize during the stepwise protocol with inhalation periods of increasing duration, we evaluated different statistical procedures based on inhalation time in relation to wheeze and current asthma. Data on random samples on 9 to 11-year-old children (n = 1,418) from two German centers were analyzed. The following statistical approaches were evaluated: (1) bronchial hyperreactivity (BHR) defined dichotomously as a fall in FEV1 (forced expiratory volume in 1 s) >or=15%; (2) PT15: the provocation time causing BHR using survival-analyses methods; (3) time-response-slope (continuous) of the individual FEV1-courses calculated by a linear model after comparing different mathematical models. The sensitivity and specificity of BHR versus current asthma were 47% and 87%, respectively. Analyses of the provocation time indicated an increased risk (adjusted hazard-ratio: 4.3; 95% CI: 2.8-6.5) for a fall in FEV1 >or= 15% among children with current asthma in comparison to those without. The time-response-slope differed markedly between children with and without wheeze and current asthma (P < 0.0001). BHR is meaningful and relatively easy to use, but has low sensitivity. Time-response-slopes utilize the available information from the stepwise protocol better than BHR and survival-analysis based on PT15. Response parameters based on inhalation time discriminate well between children with and without asthma and will be compared in the analyses of ISAAC Phase Two data.     

Indoor environmental factors associated with wheezing illness and asthma in South Korean children: phase III of the International Study of Asthma and Allergies in Childhood

Background: The relationship between exposure to indoor environmental pollutants and incidence of asthma and wheezing illness in children is unclear. This study aimed to clarify this relationship by identifying the risk factors associated with these conditions in South Korean children aged 6–7 years. Methods: The parents or guardians of 3810 children aged 6–7 years who had participated in the International Study of Asthma and Allergies in Childhood and met the study criteria completed validated questionnaires regarding their children's asthma and wheezing illness, risk factors and exposure to indoor pollutants. The data were subjected to chi-square and multivariate logistic regression analysis to identify the factors significantly associated with asthma and wheezing illness. Results: Parental history of allergic disease (odds ratio [OR]: 1.729; 95% confidence interval [CI]: 1.447–2.066), living on the basement or semi-basement floor (OR: 1.891; 95% CI: 1.194–2.996) and living in housing that had been remodeled within the last 12 months (OR: 1.376; 95% CI: 1.101–1.720) were found to be significantly associated with wheezing illness. Parental history of allergic disease (OR: 2.189; 95% CI: 1.483–3.231), male sex (OR: 1.971; 95% CI: 1.369–2.838) and positive skin prick test (SPT) result (OR: 1.583; 95% CI: 1.804–3.698) were found to be significantly associated with current asthma. Conclusions: Although the risk factors for current asthma appear to be more related to the non-modifiable risk factors like sex, parental history of allergic diseases, SPT, the two groups are associated with exposure to modifiable indoor environmental factors.     

International Study of Asthma and Allergy in Childhood Phase III (ISAAC III): The Role of Non-Response in Valencia

A study was done about non-participation during Phase III of the International Study of Asthma and Allergy in Childhood (ISAAC III) in Valencia to determine whether the non-response rate significantly affected the results obtained in Valencia. Of the schools selected to participate in ISAAC III, 13.3% denied not to, the main reason being they were already participated in a similar study. The ISAAC III questionnaire was handed out to participating schools for the parents of 6,358 schoolchildren aged 6-7 years. Of these, 53.4% responded correctly. The remaining 46.6% were given a non-response questionnaire (NRQ), of which 4.1% completed the questionnaire correctly. The main reason why parents who received the NRQ did not participate in ISAAC III was that their children had neither asthma nor other atopic disease, so interest was null. No significant statistical differences were observed between the prevalence of asthma in the schoolchildren who participated in ISAAC III and in the non-participants who answered the NRQ. These results suggest that the ISAAC III results relating to asthma are not biased by non-response.