Prevalence of Asthma in School Children on the Arizona-Sonora Border

BACKGROUND

Mexican-born children living in the United States have a lower prevalence of asthma than other US children. Although children of Mexican descent near the Arizona (AZ)-Sonora border are genetically similar, differences in environmental exposures might result in differences in asthma prevalence across this region.

OBJECTIVE

The objective of this study was to determine if the prevalence of asthma and wheeze in these children varies across the AZ-Sonora border.

METHODS

The International Study of Asthma and Allergy in Children written and video questionnaires were administered to 1753 adolescents from 5 middle schools: Tucson (school A), Nogales, AZ (schools B, C), and Nogales, Sonora, Mexico (schools D, E). The prevalence of asthma and symptoms was compared, with analyses in the AZ schools limited to self-identified Mexican American students.

RESULTS

Compared with the Sonoran reference school E, the adjusted odds ratio (OR) for asthma was significantly higher in US schools A (OR 4.89, 95% confidence interval [CI] 2.72-8.80), B (OR 3.47, 95% CI 1.88-6.42), and C (OR 4.12, 95% CI 1.78-9.60). The adjusted OR for wheeze in the past year was significantly higher in schools A (OR 2.19, 95% CI 1.20-4.01) and B (OR 2.67, 95% CI 1.42-5.01) on the written questionnaire and significantly higher in A (OR 2.13, 95% CI 1.22-3.75), B (OR 1.95, 95% CI 1.07-3.53), and Sonoran school D (OR 2.34, 95% CI 1.28-4.30) on the video questionnaire compared with school E.

CONCLUSIONS

Asthma and wheeze prevalence differed significantly between schools and was higher in the United States. Environmental factors that may account for these differences could provide insight into mechanisms of protection from asthma.

Prevalence of asthma, local risk factors and agreement between written and video questionnaires among Turkish adolescents

BACKGROUND

There is currently no standard tool for the measurement of asthma in epidemiological studies. The objectives of this study were to determine the prevalence of asthma, to describe the potential local risk factors, and to assess the agreement between written and video questionnaires in 13- to 14-year-old schoolchildren.

METHODS

We performed a cross-sectional study involving 5427 adolescents in 26 schools. Prevalence of asthma symptoms were evaluated using the International Study of Asthma and Allergies in Childhood (ISAAC) written and video questionnaire. The adolescents were asked additional questions for risk factors of asthma.

RESULTS

The prevalence of lifetime wheeze, wheeze in the last 12 months and doctor-diagnosed asthma with written questionnaire were found as 13.5%, 6.3% and 11.2% respectively. Prevalence of lifetime wheeze, wheeze in the last 12 months, wheeze after exercise in the last 12 months, with video questionnaire were found as 9.6%, 5.5%, 11.9% and 1.9% respectively. The proportion of total agreement between the two questionnaires was high (0.77-0.81) with poor kappa value (0.25-0.50). In multivariate analysis, family history of atopy, stuffed toys and accompaniment of children to their parents after school hours in textile industry were found as risk factors for asthma. In addition kind of bird, such as canary was found as a risk factor.

CONCLUSION

Prevalence of asthma is moderate in Turkey. Agreement between the two questionnaires was high. Accompaniment of children to their parents in textile industry is a newly-described risk factor for asthma.

Variability in the labeling of asthma among pediatricians

Objective

Few studies have examined variability among physicians in the perception and interpretation of asthma symptoms. We report the results of a pilot study to investigate the variability of symptom description and diagnostic labeling and nomenclature among a group of clinicians using standardized audiovisual presentations of asthma.

Methods

Practicing pediatricians in Wisconsin recruited from an electronic mailing list were shown the International Study of Asthma and Allergies in Childhood (ISAAC) video questionnaire online, and asked to describe the symptoms and signs they observed and suggest possible diagnostic labels for each presentation.

Results

A total of 113 pediatricians (mean age = 43 years; 56% female) responded to ≥1 of the 5 video scenes. The number of practitioners who described the principal symptom(s) of asthma depicted in the 5 sequences ranged from 5.5% for Scene 5 (featuring both dyspnea and wheeze), to 100% for Scene 4 (featuring cough). The number who suggested label of ‘asthma’ as a possible cause of the presentations ranged from 69.7% for Scene 3 (featuring nocturnal wheeze), to 92.7% for Scene 2 (featuring exercise induced wheeze).

Conclusion

There is important unexplained variation in the perceptions and labeling of asthma symptoms among pediatricians. These differences may influence the likelihood of diagnosis and the apparent prevalence of asthma. Many participants suggested that the ISAAC video be used in the education and training of pediatricians.

The effects of NOS1 gene on asthma and total IgE levels in Taiwanese children, and the interactions with environmental factors

Asthma is a complex disorder, which is known to be affected by interactions between genetic and environmental factors. The aim of this study was to investigate the three microsatellite polymorphisms of GT repeats in intron 2, AAT repeats in intron 20, and CA repeats in exon 29 of the NOS1 gene in 155 asthmatic children and 301 control children, and the interaction with environmental factors in southern Taiwan. Total serum IgE, phadiatop test and genetic polymorphisms were measured. The genotype frequency of 14/14-AAT repeats of the NOS1 gene was significantly higher in the asthmatic group (p = 0.01). Total IgE concentrations were higher in asthmatic children (p = 0.015) carrying the NOS1 14/14-AAT genotype than in subjects with other polymorphisms. The gene and environmental interaction effects were 3.83-fold, 6.86-fold, and 8.04-fold (all corrected p-values <0.001) between subjects carrying at least one NOS1 14-AAT allele and exposure to cockroaches, high levels of total IgE, and positive response against the phadiatop test in asthmatic children. The findings of this study provide strong evidence that NOS1 gene with 14-AAT tandem repeats has a significant effect in asthmatic children. Environmental factors and atopic status will enhance the asthmatic risk for children who carry NOS1 susceptible allele.

A video-simulation study of the management of asthma exacerbations by physicians in India

INTRODUCTION

Despite efforts to improve the management of asthma worldwide, few options exist for evaluating the specific needs or the success of these activities in a manner free from bias.

OBJECTIVES

To examine the management of asthma exacerbations by physicians using standardized audiovisual presentations of asthma.

METHODS

Practitioners (n = 70) in Chennai, India were shown the International Study of Asthma and Allergies in Childhood video questionnaire and asked to describe the clinical investigations, emergency treatments and prescription therapy they would recommend for each of the five scenes.

RESULTS

Practitioners varied significantly in their investigation and treatment of the exacerbations. Those who identified asthma as a possible cause of the scenes were more likely to recommend investigations and treatment congruent with international guidelines, as were those with additional postgraduate training and with specialty training in respiratory disease. Approaches differed significantly for scenes depicting wheeze compared with those depicting cough.

CONCLUSION

The management of asthma exacerbations varies significantly depending on whether practitioners identify asthma as a possible cause of the presentation. Standardized audiovisual depictions of asthma offer a useful tool to assess patterns of clinical practice, and to design and evaluate activities to raise the quality of care for asthma.

Extreme BMI predicts higher asthma prevalence and is associated with lung function impairment in school-aged children

BACKGROUND

The prevalence of obesity and asthma has increased in recent decades. We investigated the relationship between body mass index (BMI) and lung function, and also tried to determine if asthma prevalence differs between obese and non-obese children.

METHODS

An International Study of Asthma and Allergies in Childhood (ISAAC) video questionnaire survey that included 170,457 students in junior high school was conducted during a 1-year period. Using random selection, 15,761 students were selected for lung function testing; 14,654 (93.0%) completed the lung function tests. Multiple logistic regression analysis was used to analyze the risk factor of asthma, such as atopic diathesis, BMI, exercise habits, smoking and secondary smoking. The detailed comparison in lung functions was plotted by asthmatic versus non-asthmatic, and between both sexes.

RESULTS

The risk factor of ISAAC-identified asthma were male sex, atopy, elevated BMI, higher education levels of the parents (higher than senior high school), family smoking >or=1 pack/day, self-reported smoking. The prevalence of asthma increased as BMI elevated in both sex. The FEV1/FVC declined as BMI elevated in both sex. The thin and underweight male students had declined FEF 25-75% and PEF.

CONCLUSIONS

Extreme BMI is associated with different lung function impairment. This study showed that high BMI in both sexes was associated with low FEV1/FVC and low BMI in males are associated with poor PEF and FEF 25-75% and contributed to the symptoms of asthma.

Diagnosing asthma in children: what is the role for methacholine bronchoprovocation testing?

OBJECTIVE

To determine whether measurement of airways responsiveness to methacholine can help physicians diagnose asthma in children.

METHODS

Children from the 1995 Manitoba birth cohort were assessed by asthma specialists, had skin testing and measurement of airways responsiveness to methacholine (PC20). We selected children with doctor-diagnosed asthma and healthy children as controls (no asthma, no allergic rhinitis, negative skin tests). Sensitivities and specificities for asthma were calculated. Receiver operating curves were calculated to determine the best fit of the methacholine challenge as a diagnostic test.

RESULTS

640 children were assessed. Two hundred fifteen children with doctor diagnosed asthma and 197 healthy controls successfully completed a methacholine challenge. Airways hyperresponsiveness was a moderately sensitive and specific measure for the diagnosis of asthma in girls, whether atopic (sensitivity of 71% and specificity of 69% at PC20 < or = 4.0 mg/ml) or not (sensitivity of 77% and specificity of 53% at PC20 < or =8.0 mg/ml). Airways hyperresponsiveness was also helpful for the diagnosis of asthma in atopic boys (sensitivity of 67% and specificity of 75% at PC20 < or =2.0 mg/ml), but of absolutely no help in the diagnosis of asthma in nonatopic boys.

CONCLUSION

Measurement of airways hyperresponsiveness to methacholine can be useful in children who are atopic and of some value in nonatopic girls. The presence or absence of airways hyperresponsiveness to methacholine is of no help for the diagnosis of asthma in nonatopic boys. Laboratory tests must be placed in context of the clinical assessment of children for asthma.

Accuracy of Arabic versions of three asthma symptoms questionnaires against the clinical diagnosis of asthma

Validation studies of asthma symptom questionnaires against provocation tests of bronchial hyperresponsiveness have shown comparable performances of written and video taped questionnaires. This study aimed to determine the test characteristics of Arabic versions of two written and one video taped questionnaires when compared to the clinical diagnosis of asthma made by two respiratory physicians. The written International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire had higher sensitivities and greater accuracy than the other two questionnaires. Comparisons between corresponding questions and scenes in the ISAAC questionnaires in general revealed no significant differences in performance. The ISAAC written questionnaire had test characteristics consistent with its potential use as a screening instrument for asthma in this population of children.

Prevalence of asthma and chronic respiratory symptoms among Alaska Native children

STUDY OBJECTIVES

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

DESIGN

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

SETTING

The Yukon-Kuskokwim delta region of western Alaska.

PARTICIPANTS

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

INTERVENTIONS

No study intervention.

RESULTS

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

CONCLUSIONS

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

Issues in identifying asthma and estimating prevalence in an urban school population

This article first presents salient issues related to identifying children in urban schools who might benefit from asthma services. It discusses a brief questionnaire for identifying cases and problems in estimating asthma prevalence. Subsequently, results of case detection in 14 urban schools are presented and discussed in light of these issues. The questionnaire was employed with parents of 4,653 African-American children in Detroit. Results suggest that determining number, type, and frequency of symptoms may be necessary to ascertain prevalence of asthma. Using only number and type produced a rate of asthma of 25%. Adding frequency provided a more conservative estimate of 19%. About 9% of children exhibiting symptoms of asthma had no physician diagnosis. Only 25% with symptoms reflecting mild persistent, 35% with moderate persistent, and 26% with severe persistent disease had prescriptions for anti-inflammatory medicine. Further, 23% of children with asthma-like symptoms had no prescription for asthma medicine of any type.

CONCLUSIONS

(1) low-cost procedures can be used in schools to identify children with suspected undiagnosed and undertreated asthma; (2) prevalence estimates for asthma in the group of urban school children studied are among the highest in the United States; and (3) asthma is undertreated in this sample.

Differences in asthma prevalence between samples of American Indian and Alaska Native children

OBJECTIVES

To better understand the prevalence of asthma among American Indian and Alaska Native (AI/AN) children and to explore the contribution of locale to asthma symptoms and diagnostic assignment, the authors surveyed AI/AN middle school students, comparing responses from metropolitan Tacoma, Washington (metro WA) and a non-metropolitan area of Alaska (non-metro AK).

METHODS

Students in grades 6-9 completed an asthma screening survey. The authors compared self-reported rates of asthma symptoms, asthma diagnoses, and health care utilization for 147 children ages 11-16 self-reporting as AI/AN in metro WA and 365 in non-metro AK.

RESULTS

The prevalences of self-reported asthma symptoms were similar for the metro WA and non-metro AK populations, but a significantly higher percentage of metro WA than of non-metro AK respondents reported having received a physician diagnosis of asthma (OR 2.33; 95% CI 1.23, 4.39). The percentages of respondents who reported having visited a medical provider for asthma-like symptoms in the previous year did not differ.

CONCLUSIONS

The difference in rates of asthma diagnosis despite similar rates of asthma symptoms and respiratory-related medical visits may reflect differences in respiratory disease patterns, diagnostic labeling practices, or environmental factors. Future attempts to describe asthma prevalence should consider the potential contribution of non-biologic factors such as diagnostic practices.

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.

The impact of asthma and asthma-like illness in Seattle school children

The impact of asthma and asthma-like illness was measured in a population of 5-9-year-old Seattle public school children. Child health information was obtained from a survey of 1665 parents of first and second grade students to assess medical services use and impaired physical functioning among diagnosed asthmatics and those with current wheezing, defined as wheezing in the past 12 months without a diagnosis of asthma, relative to an asymptomatic population with neither condition. Relative to the asymptomatic population, the prevalence of respiratory-related activity limitation, and perception of poorer child health was larger among diagnosed asthmatics than children with current wheezing. However, the prevalence of sleep disturbances, school absences, medical services use, and parental concern over their child's health was similar for both the asthmatic and wheezing groups relative to the asymptomatic group. Also, in both symptomatic groups, a history of moderate or severe wheezing was associated with an increased prevalence of respiratory-related sleep disturbances and activity limitation. The similarity between the impact of diagnosed asthma and undiagnosed asthma-like illness suggests that the overall social and economic burden of asthma may be higher than previously estimated.

Prevalence of asthma, rhinitis and eczema among schoolchildren in Kelantan, Malaysia

The prevalence and severity of asthma, rhinitis and eczema in Kelantanese schoolchildren were determined as part of an international study of the epidemiology of asthma and allergic diseases. The international study of asthma and allergies in childhood (ISAAC) written questionnaire was administered to 7055 schoolchildren from February 1995 to August 1995. The respondents were parents or guardians of 5- to 7-year-old children (n = 3939), and schoolchildren aged 12-14 years (n = 3116). The ISAAC video questionnaire (AVQ3.0) was shown to children aged 12-14 years after the written questionnaire. The overall prevalences of 'ever wheezed' and 'wheezing in last 12 months' were 9.4 and 6.0% respectively. The prevalence of 'ever diagnosed with asthma' was 9.4%. Both 'ever wheezed' and 'wheezing in the last 12 months' were significantly higher in 12- to 14-year-old children than in 5- to 7-year-old children, with P values of 0.0006 and 0.014 respectively. No gender differences in the prevalences were observed. For the complete study group, 4.7% of children had sleep disturbed by wheezing but only 1.1% had a severe attack limiting speech in the preceding 12 months. Sleep disturbance was more common in the 12- to 14-year-old children than in 5- to 7-year-old children (P = 0.006). There was no difference between the age groups for severe attacks limiting speech. The overall prevalence of rhinitis and eczema symptoms were 27 and 12%, respectively. The prevalence of rhinitis in the 12-14 year age group (38.2%) was significantly higher (P < 0.0001) than in the 5-7 year age group (18.2%). The prevalence of eczema in the 5-7 year age group (13.7%) was significantly higher (P = < 0.0001) than in the 12-14 year age group (9.9%). These prevalence data are comparable with previous reports in Malaysian children, but are considerably lower than those reported for most developed countries.

Problems of measuring asthma prevalence

This review considers the issues involved in measuring the community prevalence of asthma, particularly in the context of international comparisons. We argue that there is no gold standard definition for measuring asthma prevalence, and discuss the currently available methods of case ascertainment. Prevalence studies, if they are to be generalizable, need to involve large sample sizes with high response rates. This necessitates methods that are simple, inexpensive and practicable, but also as sensitive and specific for asthma as possible. We discuss some of the issues that are specific to comparisons of asthma prevalence between diverse populations, and suggest that large surveys using written or video questionnaires of self reported symptoms validated in all of the target populations are the method of choice.