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

Value of a shortened questionnaire in the description of asthma in 10-12-year-old pupils

Asthma is a common and severe chronic disease in children influencing their quality of life and functioning at school. A 5-item asthma-screening instrument was developed and tested in 1052 children aged 10-12 years. Questionnaires were completed by parents and children separately and data were compared. Children reported less to be diagnosed by a medical doctor as having asthma compared with their parents, although children reported more to have certain asthma symptoms. No difference in prevalence of asthma was found between children and parents' answers. The absolute agreement for the scale was 92% and a good kappa agreement was found. Recoding the "don't know"-answers in "no"-answers resulted in a 4% misclassification. The short 5-item asthma screening tool can be valuable in the categorization of a subgroup of children likely to suffer from asthma in a survey. Recoding 'don't know'-answers to 'no'-answers is justified in large samples

Comparison of local risk factors for children's atopic symptoms in Hanoi, Vietnam

BACKGROUND

A 1999 study in Hanoi, Vietnam using the International Study on Asthma and Allergies in Childhood (ISAAC) questionnaire showed a high prevalence of atopic symptoms. Identifying risk factors for symptoms in these children may help in understanding the causes for these high estimates.

METHODS

An ISAAC questionnaire with supplemental questions on environmental variables was distributed to 5495 school children in Hanoi and a suburban district, Dong Anh. The response rate was 65.7%.

RESULTS

In Dong Anh, the following were among the significant age and gender adjusted associations: pig ownership [odds ratio (OR) (95% confidence interval), OR = 1.79 (1.18-2.70) for doctor-diagnosed asthma (DDA), OR = 1.72 (1.08-2.78) for doctor diagnosed hay fever (DDHF)] and farming [OR = 1.67 (1.27-2.19) for ever asthma, OR = 1.51 (1.09-2.09) for DDHF]. In multivariate models, tuberculosis (TB) was a significant predictor of atopic symptoms [Hanoi: OR = 3.09 (1.10-8.70) for DDA, Dong Anh: OR = 3.71 (1.40-9.84) for DDA, OR = 4.66 (1.88-11.57) for DDHF].

CONCLUSIONS

These findings are contrary to the "hygiene hypothesis". Recent immunologic and epidemiologic studies refute the inverse association between allergy and TB and may be one explanation for the positive association in this study. The positive association with pig ownership and farming may be because of exposures on farms in a developing country that may be different from exposures in farms of developed countries.

Peripheral blood eosinophils and IL-4 in infancy in relation to the appearance of allergic disease during the first 6 years of life

Eosinophils in peripheral blood and serum levels of interleukin (IL)-4 were analysed at 3 and 18 months and at 6 years in a prospective study comprising 67 children, of whom the majority had atopic heredity. The children were monitored from birth up to 6 years of age and the findings were related to family history of allergy and development of allergic disease. Twenty-nine children (43%) of the original group of 67 children were diagnosed as allergic at the age of six. Fifteen of 23 children with eosinophilia (>4 x 10(8) eosinophils/l) at 3 months of age were regarded as allergic at 6 years, when compared with 12 out of 38 children with normal eosinophil counts at 3 months (chi2 = 6.7, p < 0.01). Children with detectable IL-4 in serum at 18 months were more often allergic at 6 years, when compared with those children with no detectable IL-4 (chi2 = 8.6, p < 0.01). Furthermore, the allergic children had a mean IL-4 value of 0.35 microg/l (95% CI: 0.10-1.48) at 18 months, when compared with 0.17 microg/l (95% CI: 0.10-0.72, p < 0.001) in the non-allergic children. At 6 years of age, only nine children had detectable levels of IL-4 and five of them were classified as allergic. Eosinophilia at this age was also associated with allergic disease. We conclude that eosinophilia during infancy and increased levels of IL-4 at 18 month of age are associated with allergic disease during the first 6 years of life. This might indicate that the first 2 years of life are particularly important for the development of allergy.

The relation of markers of fetal growth with asthma, allergies and serum immunoglobulin E levels in children at age 5-7 years

BACKGROUND

It has been suggested that fetal growth and maturation have an impact on the development of allergic diseases later in life.

OBJECTIVE

To examine the association between measures of fetal growth and allergic disease in children at age 5-7 years.

METHODS

As part of the German International Study of Asthma and Allergies in Childhood phase II surveys, a random sample of school beginners (n=1138) was examined in 1995. Data on anthropometric measures at birth and gestational age were obtained from maternal copies of birth records. Data on symptoms and doctor-diagnosed asthma, atopic dermatitis and hayfever were gathered by parental questionnaires. Atopic sensitization was assessed by serum IgE and skin prick tests to common aeroallergens. Children (741) had complete data for the explanatory variables of interest and were thus eligible for this analysis. Confounder-adjusted prevalence odds ratios (PORs) and means ratios with 95% confidence intervals (CI) were calculated using multiple logistic and linear regression.

RESULTS

Birth weight and gestational age were positively associated with atopic sensitization (Ptrend=0.025 and 0.035, respectively). Children with a low birth weight relative to head circumference had a decreased risk of sensitization (POR 0.44, 95% CI 0.21-0.91; Ptrend=0.020). Moreover, total serum IgE increased with increasing birth weight (Ptrend=0.042). No consistent relationship was observed between markers of fetal growth and wheezing, doctor-diagnosed asthma, atopic dermatitis and hayfever.

CONCLUSION

These data suggest that fetal growth and maturity are associated with atopic sensitization and total serum IgE levels in childhood.

Prevalence of rhinitis and related-symptoms in schoolchildren from different cities in Brazil

By using the standard written questionnaire (WQ), designed for the International Study of Asthma and Allergies in Childhood (ISAAC) we determined the prevalence of rhinitis and its related-symptoms, in Brazilian children and adolescents, living in different cities of the country. The WQ was answered by the parents of 11,403 children aged 6-7 years from five Brazilian cities: Porto Alegre (South, N = 2,846), São Paulo (Southeast, N = 3,005) Uberlândia (Southeast, N = 2,991), Itabira (Southeast, N = 1,151) and Recife (Northeast, N = 1,410). The WQ was also applied to 20,587 adolescents (13-14 years old) living in: Porto Alegre (South, N = 3,195), Curitiba (South, N = 3,004), São Paulo (Southeast, N = 3,008), Uberlândia (Southeast, N = 2,998), Itabira (Southeast, N = 2,134), Salvador (Northeast, N = 3,162) and Recife (Northeast, N = 3,086). The mean response rates were 75% and 95%, for the 6-7 year-old children and for the adolescents, respectively. The data was transcribed to a database (Epi-Info) and analyzed regarding the answers to questions of rhinitis module. The mean prevalence of rhinitis (affirmative response to question 2) was 26.6% and 34.2% in the groups of 6-7 and 13-14 year-old, respectively. Applying the criteria that evaluate the association between nasal and ocular symptoms (affirmative response to question 3) the mean prevalence of allergic rhinitis were 12.8% for the 6-7 year-old children and 18.0% for the adolescents. In conclusion, the prevalence of rhinitis and its related symptoms among children and adolescents living in different Brazilian cities was as high as the prevalence observed in other areas of the world.

Asthma prevalence in European, Maori, and Pacific children in New Zealand: ISAAC study

The International Study of Asthma and Allergies in Childhood (ISAAC) demonstrated that the highest prevalence of asthma in the world is in English-speaking countries, including New Zealand. In this paper, we compare asthma symptom prevalence in the three major ethnic groups (Maori, Pacific, and European) in the six participating centers in New Zealand. Hospital admission rates for asthma are higher among Maori and Pacific children compared to European children. The working hypothesis was that there were important differences in prevalence of asthma symptoms or diagnosis between ethnic groups which might explain these observed differences in asthma morbidity. In each center in 1992-1993, we sampled approximately 3000 children at each of the age brackets 6-7 years and 13-14 years. There were 37592 participants. Maori children had higher rates of diagnosed asthma and reported asthma symptoms than Pacific children in both age groups (diagnosed asthma in 6-7-year-olds: Maori, 31.7%; Pacific, 21.2%; 95% confidence interval on difference (CID), 7.2, 13.8; P < 0.001; 13-14-year-olds: Maori, 24.7%; Pacific, 19.2%; CID 2.5, 8.5; P < 0.001; recent wheeze in 6-7-year-olds: Maori, 27.6%; Pacific, 22.0%; CID, 2.6, 8.6; P < 0.001; 13-14-year-olds: Maori, 30.8%; Pacific, 21.1%; CID, 4.8, 14.5; P < 0.001;). European children had rates intermediate between those of Maori and Pacific children (6-7-year-olds) or similar to those of Maori children (13-14-year-olds), but had the lowest prevalence of night waking with wheeze in both age groups (e.g., 6-7-year-olds: European, 2.6%; Maori, 5.8%; Pacific, 5.7%; European-Maori CID: -4.2, -2.2, P < 0.001; European-Pacific CID: -4.7, -1.7, P < 0.001; Maori-Pacific CID: -1.7, 1.8, P = 1.0). The pattern of differences closely resembled that in a 1985 Auckland study, despite a 1.5-1.7-fold overall increase in prevalence. In conclusion, there are important differences in asthma prevalence among Maori, Pacific, and European children. These differences are small compared to worldwide variation, but their pattern is stable over time. The higher rate of severe asthma symptoms that Maori and Pacific children report may be one reason for the increased asthma morbidity in these groups. Further studies are needed to determine the reasons for these apparent differences in asthma severity.

The effect of BCG vaccine at birth on the development of atopy or allergic disease in young children

BACKGROUND

Exposure to infectious diseases may reduce the development of asthma or allergy. In particular, the role of the BCG vaccine in modulating asthma or allergy has been a source of speculation.

OBJECTIVE

To study newborns from 3 international sites to evaluate the prospective effect of BCG vaccine on allergic diseases or atopic development.

METHODS

Infants were enrolled from newborn and well-infant clinics in Thailand, Argentina, and Turkey. The standard BCG vaccine for each country was given at birth. Parents who consented to have their infant included in the protocol completed an allergy family questionnaire. Infants underwent a standard purified protein derivative (PPD) test at 9 to 12 months of age, and the reaction size was measured. At the age of 2 years, the children returned to be studied. Allergy skin tests to common allergens appropriate to location and age were performed, and the parents completed the International Study of Allergy and Asthma in Childhood questionnaire. The PPD reaction size was compared with the presence of atopy and allergy questionnaire responses.

RESULTS

A total of 1,704 infants were studied. Statistical significance was found between a negative PPD response vs any positive PPD response and the risk of having an allergic history at the age of 2 years in Turkey (relative risk, 2.11; 95% confidence interval, 1.25-3.55; P = .005) and Thailand (relative risk, 2.16; 95% confidence interval, 1.18-3.94; P = .02) but not Argentina (relative risk, 1.09; 95% confidence interval, 0.70-1.68; P = .70).

CONCLUSIONS

This study further supports the role of infectious agents in modulating asthma and allergy development.

The effect of parental smoking on lung function and development during infancy

While the adverse effects of parental smoking on respiratory health during childhood are well recognized, its potential impact on early lung development is less clear. This review summarizes current evidence on the effect of parental smoking on lung function during infancy. It is difficult to separate the effects of pre- and postnatal exposure, since the majority of mothers who smoke in pregnancy (currently around 30% worldwide) continue to do so thereafter. Nevertheless, measurements undertaken prior to any postnatal exposure have consistently demonstrated significant changes in tidal flow patterns in infants whose mothers smoked in pregnancy. While there is, as yet, no convincing evidence from studies in human infants that smoking during pregnancy is associated with increased airway responsiveness at birth, many studies have demonstrated a reduction in forced expiratory flows (on average by 20%) in infants exposed to parental smoking. While maternal smoking during pregnancy remains the most significant source of such exposure and is likely to be responsible for diminished airway function in early life, continuing postnatal tobacco smoke exposure will increase the risk of respiratory infections, the combination of both being responsible for the two- to fourfold increased risk of wheezing illnesses observed during the first year of life in infants whose parents smoke. These findings emphasize the need to keep infants in a smoke-free environment both before and after birth, not least because of growing awareness that airway function in later life is largely determined by that during foetal development and early infancy.

Asthma prevalence in Melbourne schoolchildren: have we reached the peak?

OBJECTIVE

To determine the change in prevalence of asthma, eczema and allergic rhinitis in Australian schoolchildren between 1993 and 2002.

DESIGN

Questionnaire based survey, using the protocol of the International Study of Asthma and Allergy in Childhood.

SETTING

Metropolitan Melbourne primary schools within a 20 km radius of the GPO in 1993 and 2002.

SUBJECTS

All children in school years 1 and 2 (ages 6 and 7) attending a random sample of 84 schools in 1993 and 63 schools in 2002.

MAIN OUTCOME MEASURES

Parent-reported symptoms of atopic disease; treatment for asthma; country of birth.

RESULTS

There was a 26% reduction in the 12-month period prevalence of reported wheeze, from 27.2% in 1993 to 20.0% in 2002. The magnitude of reduction was similar for boys (27%) and girls (25%). The 12-month period prevalence of reported eczema increased from 11.1% in 1993 to 17.2% in 2002, and rhinitis increased from 9.7% to 12.7%. There were reductions in the proportion of children attending an emergency department for asthma in the previous year (3.6% to 2.3%), the proportion admitted to hospital (1.7% to 1.1%) and the proportion taking asthma medication (18.5% to 13.4%). Of those who reported frequent wheeze, there was an increase in the proportion taking regular inhaled steroids (34.5% to 40.9%).

CONCLUSION

There has been a significant reduction in the prevalence of reported asthma in Melbourne schoolchildren, whereas the prevalence of eczema and allergic rhinitis has continued to increase.

The effect of passive smoking on asthma symptoms,atopy,and airway hyperresponsiveness in schoolchildren

Passive smoking is a major cause of respiratory morbidity, and is associated with increased bronchial responsiveness in children. To evaluate the effect of smoking by a parent on asthma symptoms, atopy, and airway hyperresponsiveness (AHR), we conducted a cross-sectional survey of 503 schoolchildren that involved questionnaires, spirometry, allergy testing, and a bronchial challenge test. If the PC20 methacholine was less than 16 mg/mL, the subject was considered to have AHR. The prevalence of a parent who smoked was 68.7%. The prevalence of AHR was 45.0%. The sensitization rate to common inhalant allergens was 32.6%. Nasal symptoms such as rhinorrhea, sneezing, nasal itching, and nasal obstruction were present in 42.7%. Asthma symptoms such as cough and wheezing were present in 55.4%. The asthma symptoms were significantly more prevalent in children who had a parent who smoked than in those whose parents did not. The nasal symptoms, atopy, and AHR did not differ according to whether a parent smoked. In a multiple logistic regression model, the asthma symptoms and atopy were independently associated with AHR, when adjusted for confounding variables. Passive smoking contributed to asthma symptoms in schoolchildren and was not an independent risk factor of airway hyperresponsiveness in an epidemiological survey.

High prevalence of storage mite sensitization in a general adult population

BACKGROUND AND AIM

Occupational and nonoccupational storage mite (SM) allergy has received considerable attention in recent years. The study aimed to evaluate both the prevalence and factors associated with sensitization to SMs in a general adult population from a warm and humid area where mites are the predominant allergens.

PATIENTS AND METHODS

An age-stratified random sample of 720 subjects was drawn from the population older than 18 years of A-Estrada (Galicia, Spain). From 697 eligible subjects, 469 (67%, median age 54 years, range 18-92 years, 44% males, 75% of cases from a rural environment) agreed to participate. Skin prick tests to SMs (Lepidoglyphus destructor and Tyrophagus putrescentiae), house dust mite (Dermatophagoides pteronyssinus), pollens, moulds and animal danders were performed in all cases. Wheals >or= 4 mm were considered positive. Epidemiological data were assessed by questionnaire. A design-based analysis was performed and all calculations were weighted to give unbiased estimates.

RESULTS

Tyrophagus putrescentiae and L. destructor were the leading causes of allergic sensitization throughout all ages. SM sensitization was found in 104 cases (weighted value 24.4%, 95% CI 20.6-28.2). SM sensitization was inversely associated with age. Multivariate analysis showed that SM sensitization was not significantly associated with sex, smoking, educational level, farming profession, rural environment, indoor humidity, presence of pets, livestock or grain storage facilities near home.

CONCLUSIONS

SMs (T. putrescentiae and L. destructor) are major aeroallergens in adults in the region studied, even in subjects without occupational exposure.

Early radiographic and clinical features associated with bronchiectasis in children

Bronchiectasis among children living in developing regions is associated with respiratory infections during early childhood, but specific risk factors that precede childhood bronchiectasis are not fully characterized. We hypothesized that severe respiratory syncytial viral (RSV) infection in infancy would increase the risk of bronchiectasis among Alaska Native children in rural Alaska. This was a follow-up cohort study of a 1993-1996 case-control study of RSV-hospitalized case patients and their controls. For each 5-8-year-old former case-patient and control subject, we reviewed medical records, interviewed parents, performed physical examinations and spirometry, collected sera, and analyzed all historical chest radiographs. Ten (11%) RSV cases and 10 (9%) controls had radiographic evidence of bronchiectasis. The mean age at radiographic diagnosis of bronchiectasis was 3.3 years (range, 1.2-6.1 years). Children were more likely to develop bronchiectasis if their chest radiographs, when they were < 2 years of age, showed lung parenchymal densities (RR = 3.9, P < 0.013), persistent parenchymal densities > 6 months' duration (RR = 3.0, P = 0.02), or infiltrates on multiple episodes (test for trend, P = 0.003). Radiographic features of hyperinflation and atelectasis among children < 2 years old were not associated with eventual bronchiectasis. A single severe infection with RSV alone did not predispose Alaska Native infants to bronchiectasis. Childhood bronchiectasis was associated with lung and hence airway injury, manifested on radiographs by parenchymal densities or "pneumonia" rather than by hyperinflation or atelectasis.

Predictors of health care utilization of children with asthma in the community

The aim of this study was to assess the pattern of use of health care services among children with asthma symptoms within the community, and assess groups at increased risk of emergency department (ED) visits or hospital admissions (HA). Using International Study of Asthma and Allergies in Childhood phase II protocol, information about asthma management and utilization of health care services was collected by parental questionnaire in a community-based random sample of 5-7- and 9-11-year-old children (n = 11,094) in Dresden and Munich. Only 11.2% of children with current wheeze did not utilize any health care facility or consultation for their asthma symptoms in the 12 months prior to survey, while 86.2%, 12.3%, and 3.6% had at least one asthma related physician's consultation, ED visits, or HA, respectively. Predictors of ED visits and HA among current wheezers were: younger age, male gender, speech-limiting wheeze, level of exposure to environmental tobacco smoke. In addition, children of low socioeconomic status were more likely to have ED visits because of their asthma. Childhood asthma is a major public health problem in Germany leading to substantial morbidity and utilization of health care services. Exposure to tobacco smoke comes out as the major modifiable risk factor related to asthma morbidity in children.

Prevalence and correlates of paediatric asthma and wheezing in a largely rural USA population

OBJECTIVE

The prevalence of asthma among children has been increasing in the United States and it is estimated that there are approximately 5 million children with asthma. This cross-sectional survey sought to estimate the prevalence of asthma and asthma symptoms and potential risk factors among children aged 16 and younger, in a largely rural population in the USA.

METHODS

This study was a telephone survey of 1500 households in the South Plains/Panhandle region of Texas. Parents of children were interviewed with a response rate of 64%. Having been diagnosed with asthma by a physician and a report of wheezing in the last 12 months were used as dependent variables in multivariate logistic regressions with several sociodemographic and environmental factors as potential confounders.

RESULTS

The age-adjusted prevalence of asthma and wheezing among children were approximately 15 and 18%, respectively. The prevalence of asthma was highest (20%) among children aged 11-16 (P < 0.001). Living in urban areas was associated significantly with asthma and wheezing. Non-Hispanic blacks reported significantly increased odds of asthma in their children (adjusted odds ratio (OR) = 2.04, 95%CI 1.02-4.08), whereas Mexican-Americans reported significantly reduced odds of asthma (adjusted OR = 0.48, 95%CI 0.29-0.78) and wheezing (adjusted OR = 0.58, 95%CI 0.37-0.89) in their children. The odds of asthma (adjusted OR = 1.78, 95%CI 1.09-2.92) and wheezing (adjusted OR = 2.45, 95%CI 1.52-3.95) was highest among children in the highest body mass index quartile. No significant association with pet ownership and exposure to second-hand smoke with asthma and wheezing was observed in this study.

CONCLUSION

Urban residence, non-Hispanic black and Mexican-American race/ethnicity, and being overweight were significantly associated with the increased risk of asthma and/or wheezing.

Prevalence and risk factors for allergic rhinitis and atopic eczema among schoolchildren in Israel: results from a national study

BACKGROUND

There is growing evidence that the prevalence rates of asthma and allergic diseases are increasing, especially among children. Several risk factors are under investigation.

OBJECTIVE

To evaluate the prevalence and risk factors for allergic diseases, including allergic rhinitis (AR) and atopic eczema (AE), among 13- to 14-year-old schoolchildren in Israel.

METHODS

A modified version of the International Study of Asthma and Allergies in Childhood written questionnaire was administered to a national sample of schoolchildren 13 to 14 years old in Israel. The questionnaire was completed by the schoolchildren themselves.

RESULTS

There were 10,057 complete questionnaires available for analysis. The prevalence of AR symptoms ever and current AR were 41.6% and 9.4%, respectively. Allergic rhinoconjunctivitis symptoms ever were reported by 15.8% of the children. The prevalence rates of 6 months of itchy rash ever and AE were 5.9% and 7.8%, respectively. After adjustment for demographic and environmental factors, current asthma, parental history of asthma, and population group were the most significant risk factors for current AR (odds ratio [OR], 4.47; 95% confidence interval [CI], 3.70-5.40; OR, 1.30; 95% CI, 1.02-1.66; and OR, 1.75; 95% CI 1.45-2.13; respectively) and AE (OR, 2.30; 95% CI, 1.80-2.90; OR, 1.80; 95% CI, 1.40-2.30; and OR, 1.70; 95% CI, 1.40-2.00; respectively).

CONCLUSIONS

Israeli children have a low prevalence rate of current AR and a midrange rate of AE. Arabs have lower prevalence rates of allergic diseases than Jews, and the prominent risk factors for those diseases are current asthma and parental history of asthma.

Association of the interleukin-1 receptor antagonist gene with asthma

The interleukin-1 cluster on human chromosome 2q12-2q14 harbors various promising candidate genes for asthma and other inflammatory diseases. We conducted a systematic association study with single-nucleotide polymorphisms (SNPs) located in candidate genes situated in this cluster. Single-marker, two-locus and three-locus haplotype analysis of SNPs yielded several significant results (p < 0.05-0.0021) for the human IL1RN gene encoding the IL-1 receptor antagonist protein, an antiinflammatory cytokine that plays an important role in maintaining the balance between inflammatory and antiinflammatory cytokines. These findings were replicated and confirmed in an independent Italian family sample in which significant, although weaker, association with asthma was detected. A sequencing approach to the coding region of the human IL1RN gene revealed additional DNA variants, from which a selection was also associated with the disease in German and Italian samples. Calculation of the linkage disequilibrium for the human IL1RN gene showed strong linkage disequilibrium for nearly all analyzed SNPs. Further haplotype analysis indicated that six SNPs are sufficient for tagging all haplotypes with a prevalence of more than 1%. The most frequent haplotype constructed from these SNPs was 1.4-fold overtransmitted in the German family sample.

Effect of PM10 pollution in Bangkok on children with and without asthma

This study aimed to investigate the effects of PM10 concentrations exceeding the Thai national standard (24-hr average, >120 microg/m3) on daily reported respiratory symptoms and peak expiratory flow rate (PEFR) of schoolchildren with and without asthma in Bangkok. The 93 asthmatic and 40 nonasthmatic schoolchildren were randomly recruited from a school located in a highly congested traffic area. Daily respiratory symptoms and PEFR of each child were evaluated and recorded in the diary for 31 successive school days. During the study period, 24-hr average PM10 levels ranged between 46-201 microg/m3. PM10 levels exceeded 120 microg/m3 for 14 days. We found that when PM10 levels were >120 microg/m3, the daily reported nasal irritation of asthmatic children was significantly higher than when PM10 levels were < or =120 microg/m3. In addition, when PM10 levels were >120 microg/m3, nonasthmatic children had a significantly higher daily reported combination of any respiratory symptoms. PEFR did not change with different ambient PM10 levels in both groups. This study suggests that elevated levels of PM10 concentrations in Bangkok affect respiratory symptoms of schoolchildren with and without asthma.

Wheeze and urban variation in South Asia

Typically, urban South Asia is characterised by narrow streets, heavy traffic, visible haze, unplanned city architecture and the use of kerosene or wood-burning stoves at home. However, some urban areas in South Asia are clean and modern, with concrete housing, vehicle emission regulations and use of smoke-free household fuel. The purpose of this study was to compare wheeze prevalence in 13-14-year-olds between two South Asian cities (Galle, Chandigarh), representing each of the above two archetypes. The validated one-page International Study on Asthma and Allergies in Childhood (ISAAC) questionnaire for 13-14-year-olds was used for the study. Of 1814 distributed questionnaires, 1737 (95.8%) were completed correctly and returned (Galle: n=1162; Chandigarh: n=575). Crude prevalence rates, and prevalence odds ratios (with 95% two-sided confidence intervals (CI) for comparison of prevalence rates), were calculated. The prevalence rate for wheezing in Galle (28.7%) was higher than in Chandigarh (12.5%). The prevalence odds ratios (Galle versus Chandigarh) for lifetime wheezing (2.3; 1.8-2.9), wheezing in the previous year (2.1; 1.6-2.7), exercise-related wheeze (4.8; 3.5-6.7) and physician-diagnosed wheeze (1.7; 1.2-2.3) demonstrated significant differences in wheeze prevalence between the two cities ( P<0.05). The numbers of 13-14-year-olds experiencing less than 12 wheezing episodes per year or sleep disturbance due to wheeze of less than 1 night per week were also significantly higher for Galle than Chandigarh. There is a higher prevalence of wheeze in 13-14-year-old children living in an old-fashioned, congested city than in a clean and modern city in South Asia.

Risk factors for an intensive care unit admission in children with asthma

An admission to an intensive care unit (ICU) with asthma is a marker of asthma severity and may be a precursor of asthma death. The aim of this study was to investigate risk factors for acute severe asthma needing an ICU admission. We hypothesized that children admitted to the ICU represent a severe phenotype with identifiable premorbid clinical features. The study was case-control in design. One hundred and forty-one children were studied. Seventy children admitted to the ICU and 71 children admitted to the general medical ward served as cases and controls, respectively. Children were aged between 1-16 years. They underwent skin prick allergy testing, and had a nasopharyngeal aspirate and serology performed to screen for respiratory pathogens. Their parents completed an asthma and allergy symptom questionnaire and the Newcastle Asthma Knowledge Questionnaire (NAKQ). On univariate analysis, an admission to the ICU was more likely in children with 1) "frequent episodic" or "persistent" background asthma; 2) three or more previous admissions for asthma; 3) one or more asthma admissions in the previous 12 months; 4) three or more presentations to the Emergency Department (ED) in the preceding 12 months; 5) three or more positive responses on skin prick allergy testing; 6) an elevated IgE level; 7) oxygen saturation on presentation < or =91%; 8) longer duration of asthma; 9) lower level of maternal education; 10) an admission during autumn; 11) three or more siblings; and 12) being prescribed antibiotics. Risk factors that remained significant on multivariate analysis were three or more presentations to the ED in the preceding 12 months (P=0.003), an elevated IgE level (P=0.01), oxygen saturation on presentation < or =91% (P=0.003), and longer asthma duration (P=0.02). ICU patients took longer to see a doctor and to commence oral steroids. No differences were found between cases and controls in the proportion taking preventer therapy (58% vs. 52%), provided with a written asthma action plan (32% vs. 25%), or in whom spirometry or peak flow was measured (28% vs. 42%). However, rates were low in both groups. Parental asthma knowledge was generally poor. This study identified risk factors for an ICU admission in children with asthma. A potentially preventable risk factor is a history of multiple ED presentations in the past year. Specialist referral of children with multiple ED presentations may improve asthma control and reduce the risk of an ICU admission. Background asthma management remains suboptimal in children needing hospitalization.

Prevalence of asthmatic phenotypes and bronchial hyperresponsiveness in Turkish schoolchildren: an International Study of Asthma and Allergies in Childhood (ISAAC) phase 2 study

BACKGROUND

Numerous epidemiologic studies have revealed that bronchial asthma affects populations without regard to frontiers. However, standardized methodological approaches are necessary to compare these populations.

OBJECTIVE

To investigate objective markers of childhood asthma on an epidemiologic basis and to include Turkish children in international comparisons.

METHODS

Parental questionnaires were collected and skin prick tests performed on fourth grade primary schoolchildren, aged 8 to 11 years, residing in Ankara, Turkey. Pulmonary function tests and bronchial challenge with hypertonic saline (HS) were conducted in children selected from this cohort with a stratified random sampling according to the presence of current wheezing.

RESULTS

A total of 3,041 questionnaires were included in the evaluation. Skin prick tests were performed on 2,774 children (97.1%). A total of 347 children from this cohort underwent pulmonary function and bronchial challenge tests. In 18 (5.1%) of the 347 children, bronchial challenge tests could not be successfully completed. The prevalence values were 11.5% for current wheezing, 6.9% for physician-diagnosed asthma, and 7.7% for physician-diagnosed recurrent bronchitis. Population-based weighted prevalence of bronchial hyperresponsiveness (BHR) was 21.8%. Frequency of responses to HS was 38.6% among physician-diagnosed asthma cases and 30.5% among patients with current wheezing. Skin test positivity was present in 38.7% of the children with a diagnosis of asthma or asthmatic bronchitis, 35.0% of current asthmatic patients, and 19.2% of patients with current wheezing.

CONCLUSIONS

Objective markers, in addition to the questionnaire-based prevalence figures, need to be used in epidemiologic surveys for asthma, especially in countries with inadequate health care facilities or problems with interpretation of the wheeze concept.

The association of maternal but not paternal genetic variation in GSTP1 with asthma phenotypes in children

Maternal factors including atopy and smoking during pregnancy are associated with asthma risk during childhood. Suggested mechanisms include transmission of specific maternal alleles and maternal influences on the intrauterine environment. We have previously shown that polymorphism in glutathione S-transferase, GSTP1 is associated with airway hyperresponsiveness (AHR) and atopy in adults. We now hypothesise that GSTP1 genotypes in the mother and child, but not the father, mediate asthma phenotypes in the child. One hundred and forty-five Caucasian families were recruited via an asthmatic proband aged 7-18 years. Atopy and asthma were assessed using a questionnaire, skin prick testing, serum IgE, spirometry and methacholine challenge (PC20, dose-response slope--DRS). GSTP1 genotyping was determined using PCR. GSTP1 Val105/Val105 genotype in the child was associated with a reduced risk of atopy (P = 0.038) and AHR (PC20, P = 0.046; DRS, P = 0.032). In mothers (P = 0.014) but not fathers (P = 0.623), Val105/Val105 was associated with a reduced risk of AHR in the child. We have identified, for the first time, an association between maternal genotype and the child's asthma phenotype that appears not to be due to transmission of specific maternal alleles. This preliminary data supports the view of in utero effects of maternal genotype and adds new insights into the possible mechanisms by which maternal factors may influence development of childhood asthma.

Decreased Respiratory Symptoms After Intervention in Artificially Ventilated Offices in São Paulo, Brazil

BACKGROUND

The increase in work-related respiratory complaints in artificially ventilated buildings have multiple causes, and intervention studies are a valuable approach to understanding possible mechanisms.

STUDY OBJECTIVES

To analyze the effects of an intervention in a ventilation system with > 20 years of continuous use, and with a high rate of building-related respiratory complains.

DESIGN

An epidemiologic study was done among individuals working in places with ventilation machinery and ducts with > 20 years of use, before and after intervention. Analysis of symptoms and logistic regression were performed to check the associations between air-conditioning intervention and reported symptoms.

RESULTS

The air-conditioning intervention showed a protective effect on building-related worsening of respiratory symptoms (odds ratio, 0.132; 95% confidence interval, 0.030 to 0.575), naso-ocular symptoms (odds ratio, 0.231; 95% confidence interval, 0.058 to 0.915), and persistent cough (odds ratio, 0.071; 95% confidence interval, 0.014 to 0.356).

CONCLUSION

Intervention in high-risk occupational locations can be effective in improving perceived indoor air quality.

Risk factors for atopic dermatitis in infants at high risk of allergy: the PIAMA study

BACKGROUND

It has been suggested that the period immediately after birth is a sensitive period for the development of atopic disease.

OBJECTIVE

We investigated whether birth characteristics and environmental factors are associated with the development of atopic dermatitis in the first year of life.

METHODS

Seventy-six children with and 228 without atopic dermatitis, all children of mothers with respiratory allergy or asthma (PIAMA birth cohort study) were included in the study. Atopic dermatitis was defined as a positive history of an itchy skin condition with at least two of the following characteristics: visible dermatitis, history of outer arms/leg involvement, or general dry skin. Multiple logistic regression analysis was performed to study the independent effects of various risk factors.

RESULTS

A birth weight >/=4000 g compared to 3000-4000 g was a significant risk factor for atopic dermatitis (odds ratio (OR)=2.4; 95% CI: 1.1-5.1) as was day care attendance (OR=2.9; 95% CI: 1.5-5.9). Exclusive breastfeeding in the first 3 months was negatively associated with atopic dermatitis (OR=0.6; 95% CI: 0.3-1.2), especially with visible dermatitis (OR=0.4; 95% CI: 0.2-1.0). Gender, gestational age, the presence of siblings or pets, and parental smoking were not significantly associated with atopic dermatitis.

CONCLUSION

This study shows that a high birth weight and day care attendance increase the risk of atopic dermatitis in the first year of life, while exclusive breastfeeding is a protective factor when dermatitis is found on inspection.

Allergic manifestations in patients with rheumatoid arthritis

A functional dichotomy between Th1- and Th2-type immune responses has been suggested. This study was performed to investigate whether rheumatoid arthritis (RA), a disease with indications of Th1-deviated immune activation, is inversly related to atopic conditions which are Th2-mediated. Two hundred and sixty-three adult cases of RA, fulfilling the American Rheumatism Association (ARA) 1987 Revised Classification Criteria for RA, were identified in 1995 and compared with 541 randomly selected population referents. The presence of atopic manifestations was established through a postal questionnaire and by demonstrating circulating IgE antibodies to common allergens. RA was inversely associated with certain manifestations of rhinitis, which were regarded as the most reliable indicators of atopic disease in the present study. However, no negative association was seen between RA and asthma and eczema, respectively. The main results give some support for an inverse relationship between RA and rhinitis. The prevalence of circulating IgE antibodies was however similar in cases and controls, suggesting that the T-cell commitment mainly occurs in the affected organs.

Do risk factors for childhood infections and malnutrition protect against asthma? A study of Brazilian male adolescents

OBJECTIVES

We studied the association between early life conditions and asthma in adolescence.

METHODS

We conducted a population-based birth cohort study involving 2250 male 18-year-olds residing in Brazil.

RESULTS

Approximately 18% of the adolescents reported having asthma. Several childhood factors were found to be significantly associated with increased asthma risk: being of high socioeconomic status, living in an uncrowded household, and children being breastfed for 9 months or longer.

CONCLUSIONS

The present results are consistent with the "hygiene hypothesis," according to which early exposure to infections provides protection against asthma. The policy implications of our findings are unclear given that risk factors for asthma protect against serious childhood diseases in developing countries.

Repeatability of bronchial responsiveness to mannitol dry powder in children with asthma

Our objective was to determine the repeatability of bronchial responsiveness to mannitol dry powder (MDP) as an objective marker of asthma in children. MDP challenge was performed in children with stable asthma at the same time of the day on two separate occasions within a week. The test was terminated after a 15% fall of forced expiratory volume in 1 sec (FEV1) and the provocative dose to produce a 15% fall in FEV1 (PD15) were calculated. Seventeen children (aged 9-16 years) on inhaled corticosteroids (200-1,500 mcg) were studied. Mean baseline FEV1 before the challenges were 95% (81-119) and 96% (74-121), respectively, with a standard deviation of differences of 5.2%. PD(15) values ranged from 7-387 mg, with a geometric mean of 38 mg for the first and 49 mg for the second test. Of the 17, all but two pairs of tests achieved a PD15 within one dose of capsules. Four children had a negative challenge on two occasions. A high relative reliability was reflected by a concordance coefficient of 0.86. In conclusion, MDP is a convenient challenge which is easy to administer and is well-tolerated by children. It is a highly reproducible test of airway responsiveness in children with moderate to severe persistent asthma on inhaled corticosteroids within 7 days under laboratory conditions.

Birth order and sibship size as independent risk factors for asthma, allergy, and eczema

This study was carried out to disentangle the independent relations of birth order and sibship size with the presence of asthma, allergy and eczema. In a retrospective study, 700 families in the Netherlands were selected with index children born in 1988-90. Data were extracted from reports of health examinations at the age of 6 years of these children and their siblings. Birth order, and not sibship size, appeared to be a strong risk factor for allergy (excluding eczema). Children with higher birth order had a lower risk of allergy compared with first-borns (adjusted odds ratios: 0.43, 0.26 and 0.05 for second-, third- and fourth- or higher borns, respectively; p < 0.0001). Allergy including eczema also had a significant relation with birth order (p = 0.01). For asthma there appeared no clear relation with birth order. For asthma a non-significant relationship with sibship size (adjusted for birth order) was found (p = 0.06): first-born children in small sibships were more at risk than those in larger sibships. For allergy and eczema no such trend was observed. In conclusion, birth order is inversely related to the risk of allergy, independent of the size of the sibship.

Prevalence of asthma and related symptoms in Sivas, Central Anatolia

BACKGROUND

In our clinical experience, asthma is an important health problem in our region, but we did not know its prevalence.

OBJECTIVE

The main objective of our study was to assess the prevalence of asthma in Sivas, a city in Central Anatolia.

METHODS

A cross-sectional study was performed using a screening questionnaire adopted from European Community Respiratory Health Survey (ECRHS). A total of 5448 adults of both genders between 20 and 107 yr of age living in Sivas, a city in the central region of Anatolia in Turkey, participated in the survey. Of the cohort, 2691 were men (49.4%) and 2757 (50.6%) were women.

RESULTS

The mean age was 38.2 yr (SD = 12.7 yr), almost half of the study population was at or younger than 40 yr of age. The prevalence of wheezing in the last 12 months, diagnosis of asthma, asthma attack in the last 12 months, and use of asthma medicine were 20.9%, 4.5%, 4.9%, and 3.4%, respectively. Awakening with chest tightness, with shortness of breath, or with cough were reported as 14.2%, 14.8%, and 22.7%, respectively. The prevalence of respiratory symptoms related to asthma was statistically higher in women than that of men (p = 0.000, OR 1.346, 95% CI: 1.228-1.475). Those who had asthma/allergic symptoms in their family members were significantly younger than others (p: 0.001).

CONCLUSIONS

The results of this study demonstrate that symptoms suggestive of asthma are quite common and constitute a major health problem in Sivas, Turkey. This study also showed that, despite a high rate of reported symptoms exists, the rate of diagnosis and treatment of asthma is low among the adult population in Sivas.

Elevated asthma and indoor environmental exposures among Puerto Rican children of East Harlem

OBJECTIVE

East Harlem in New York City, a community with a large Puerto Rican population, has among the highest rates of asthma hospitalizations and mortality in the United States, but it is not known if the high rates are related to the ethnic composition, environmental or community factors, or if the higher rates reflect differentials in access to appropriate asthma care. A survey was conducted to: (a) estimate the prevalence of current asthma by ethnicity among school-age children, (b) assess indoor environmental risk factors for childhood asthma, and (c) assess health care utilization and school absences associated with childhood asthma.

DESIGN

A cross-sectional survey of parents of elementary school children, using a self-administered questionnaire with a 12-month recall on asthma symptoms based on the International Study of Asthma and Allergies in Childhood.

SETTING

Two public elementary schools in East Harlem (n = 1615 students 5-12 years of age).

RESULTS

Among the 1319 respondents (response rate 82%), the prevalence for current asthma (doctor or nurse diagnosis at any time plus wheezing in the past 12 months) was 23%. Puerto Rican children had a prevalence of 35%. Puerto Rican children reported both higher symptomatic frequencies and higher rates of physician diagnosis. Living in a home where cockroaches, rats, or mice had been seen in the past month and with a dust-enhancing heating system also was associated with having asthma, regardless of ethnicity. Compared with other children with asthma, Puerto Rican children with asthma were more likely to live in homes where rats or mice had been seen in the past month. Regardless of ethnicity, children with more frequent, more severe asthma symptoms and incomplete asthma action plans were more likely to have visited the emergency department in the past year. Puerto Rican children were more likely to have missed school because of their asthma in the past year.

CONCLUSION

The prevalence of current asthma was significantly higher among Puerto Ricans, who had higher symptomatic frequency and greater diagnosis rates. Although all children with asthma in the East Harlem study appear to be sensitive to selected indoor environmental risk factors, only Puerto Rican children with asthma appear to be sensitive to the presence of rodents in their buildings. However, their higher school absence rate suggests problems with routine asthma management that could be addressed by improved medical management, programs to help parents manage their children's asthma, or school staff assistance with medications.

Interrupter resistance and wheezing phenotypes at 4 years of age

It is difficult to distinguish young children with respiratory symptoms who will develop asthma from those with transient symptoms only. Measurement of interrupter resistance may help to identify children at high risk of asthma. The aim of this study is to compare interrupter resistance in 4-year-old children with different wheezing phenotypes. All children participated in the Prevention and Incidence of Asthma and Mite Allergy cohort, a prospective birth cohort of more than 4,000 children. At 4 years of age, data on interrupter resistance plus wheezing phenotype were available for 838 children. Mean interrupter resistance values (95% confidence interval) were 0.95 (0.93, 0.97), 0.95 (0.92, 0.98), 0.96 (0.87, 1.05), and 1.08 (1.02, 1.14) kPa.L(-1).second for never (n = 482), early transient (n = 236), late-onset (n = 22), and persistent (n = 98) wheezing phenotypes, respectively. Additional analyses were performed for children with atopic and nonatopic mothers separately. Both in children with atopic and nonatopic mothers, children with persistent wheeze had significantly higher interrupter resistance values than children with never and early wheeze. In conclusion, mean interrupter resistance values were higher in children with persistent wheeze as compared with children with never and early transient wheezing phenotypes.

Indoor and outdoor environmental exposures, parental atopy, and physician-diagnosed asthma in Taiwanese schoolchildren

OBJECTIVE

Parental atopy and environmental exposures are recognized risk factors for childhood asthma. However, the relative contributions of specific risk factors and the overall contributions of indoor and outdoor exposures remain unexplored. This study was undertaken to identify risk factors, estimate the population attributable risk of each exposure, and compare the data for boys versus girls for physician-diagnosed asthma in Taiwanese schoolchildren.

METHODS

During a February to June 2001 cross-sectional national survey, 35 036 6- to 15-year-old schoolchildren were chosen from 22 elementary and 22 middle schools located within 1-km catchment areas of 22 air-monitoring stations in Taiwan. The main outcome measure was physician-diagnosed asthma, as reported by the parents. We investigated hereditary and indoor and outdoor environmental factors for childhood asthma by questionnaire. The adjusted prevalences of questionnaire-determined outdoor indicators were also compared with air-monitoring data.

RESULTS

Outdoor air pollutants were associated with parent-reported perceived ambient air pollution. Physician-diagnosed asthma was reported for 8.1% of the boys (1330 of 16 441) and 5.6% of the girls (894 of 16 056). The risk of physician-diagnosed asthma was significantly associated with parental atopy and perceived ambient air pollution in both sexes. The presence of visible cockroaches (odds ratio [OR]: 1.30; 95% confidence interval [CI]: 1.07-1.59), mold on walls at home (OR: 1.20; 95% CI: 1.01-1.41), and water damage (OR: 1.33; 95% CI: 1.02-1.70) were also associated with asthma in girls; however, only visible mold on walls at home was related to asthma in boys. Mutually adjusted analytical models produced statistically significant associations between any indoor factor and asthma in girls (OR: 1.24; 95% CI: 1.00-1.56) but not in boys (OR: 1.04; 95% CI: 0.87-1.25). For all hereditary and environmental factors, the total population attributable risk was 44.31% in boys and 60.61% in girls.

CONCLUSIONS

Parental atopy contributed more to childhood asthma than indoor or outdoor environmental factors. Girls may be more susceptible to indoor factors than boys.

Assessment of respiratory symptoms and asthma prevalence in a U.S.-Mexico border region

The authors studied children who were 10-12 yr of age and who resided in sister cities in a U.S.-Mexico border region to determine the prevalence of asthma and respiratory symptoms. The relationship of symptoms to ambient levels of particulate matter less than 10 microm in diameter (PM10), and to several indoor environmental conditions, was assessed. The study was conducted in the border cities of Ambos Nogales (Nogales, Arizona [United States], and Nogales, Sonora [Mexico]). At the beginning of the 11-wk study, during the autumn of 1996, 631 students and their parents completed baseline questionnaires. While in school, the children completed daily symptom diaries and daily peak expiratory flow maneuvers. PM10 values and daily temperatures were also measured. The authors found that the prevalence of self-reported asthma among 5th-grade students was comparable on both sides of the border (i.e., 7.6% on the Arizona side and 6.9% on the Sonora side). Wheezing was a frequent complaint (29.5-35.6%), as was cough (16.8-29.6%). Smoking in the home was common on both sides of the border, and it was associated with a greater occurrence of self-reported asthma and respiratory complaints. Increased respiratory symptoms were also associated with increased ambient PM10 levels. The prevalence of respiratory symptoms such as wheezing and frequent cough among all children in this study, combined with the limitations inherent in self-reporting, suggest that asthma may actually be more prevalent than has been previously reported.

Proactive asthma care in childhood: general practice based randomised controlled trial

OBJECTIVES

To assess the feasibility and effectiveness of a general practice based, proactive system of asthma care in children.

DESIGN

Randomised controlled trial with cluster sampling by general practice.

SETTING

General practices in the northern region of the Australian Capital Territory.

PARTICIPANTS

174 children with moderate to severe asthma who attended 24 general practitioners.

INTERVENTION

System of structured asthma care (the 3+ visit plan), with participating families reminded to attend the general practitioner.

MAIN OUTCOME MEASURES

Process measures: rates for asthma consultations with general practitioner, written asthma plans, completion of the 3+ visit plan; clinical measures: rates for emergency department visits for asthma, days absent from school, symptom-free days, symptoms over the past year, activity limitation over the past year, and asthma drug use over the past year; spirometric lung function measures before and after cold air challenge.

RESULTS

Intervention group children had significantly more asthma related consultations (odds ratio for three or more asthma related consultations 3.8 (95% confidence interval 1.9 to 7.6; P = 0.0001), written asthma plans (2.2 (1.2 to 4.1); P = 0.01), and completed 3+ visit plans (24.2 (5.7 to 103.2); P = 0.0001) than control children and a mean reduction in measurements of forced expiratory volume in one second after cold air challenge of 2.6% (1.7 to 3.5); P = 0.0001) less than control children. The number needed to treat (benefit) for one additional written asthma action plan was 5 (3 to 41) children. Intervention group children had lower emergency department attendance rates for asthma (odds ratio 0.4 (0.2 to 1.04); P = 0.06) and less speech limiting wheeze (0.2 (0.1 to 0.4); P = 0.0001) than control children and were more likely to use a spacer (2.8 (1.6 to 4.7); P = 0.0001). No differences occurred in number of days absent from school or symptom-free day scores.

CONCLUSIONS

Proactive care with active recall for children with moderate to severe asthma is feasible in general practice and seems to be beneficial.

Respiratory health in Aboriginal and Torres Strait Islander children in the Australian Capital Territory

OBJECTIVES

To measure the prevalence of respiratory symptoms and atopic disease in Aboriginal and Torres Strait Islander (indigenous) and non-indigenous children in the Australian Capital Territory (ACT).

METHODS

A two-stage questionnaire survey of children in the ACT with stage two completed for children identified by parents as having respiratory symptoms or asthma in the first stage cross-sectional survey. Participants in the study were: (i) all new entrant primary schoolchildren aged 4-6 years in 1999, 2000 and 2001, 217 being indigenous children and 10 604 being non-indigenous children (80% of eligible); and (ii) Year 1-6 primary schoolchildren in 2000, with 216 being indigenous children and 14 202 being non-indigenous children (52% of eligible). Respiratory symptoms (including recent wheeze and parent-reported asthma) and other factors were measured by parental questionnaire.

RESULTS

Indigenous kindergarten children had more recent wheeze (21%, odds ratio (OR) 1.4 95% confidence interval (CI) 1.0-2.0)) and parent-reported asthma (24%, OR 1.8 95% CI 1.3-2.5) than non-indigenous children (both 15%). However, indigenous children had less eczema (25%, OR 0.7 95% CI 0.5-0.9) and hayfever (14%, OR 0.7 95% CI 0.5-1.0) than non-indigenous children (32% and 19%, respectively). Among children with respiratory symptoms, the symptom severity did not differ between groups, but indigenous children were exposed to more environmental tobacco smoke (ETS) (63%, OR 3.5 95% CI 2.1-5.9) than non-indigenous children (32%).

CONCLUSIONS

Indigenous children in the ACT have more respiratory morbidity but less of the atopic diseases of hayfever and eczema than non-indigenous children. Whether the respiratory morbidity represents 'asthma' or results from increased ETS exposure is unclear and needs to be further explored.

Migration to a western country increases asthma symptoms but not eosinophilic airway inflammation

The prevalence of asthma symptoms varies markedly throughout the world. However, the asthma mechanisms involved are not defined. Studying the effects of migration can help identify the reasons for this geographic variation. The aims of this study were to examine the prevalence of asthma symptoms, airway hyperresponsiveness (AHR), and induced sputum eosinophils in adolescents who migrate to Australia. The study was conducted in Sydney, Australia, where adolescent students completed a video symptom questionnaire, hypertonic saline challenge, sputum induction, and allergy skin testing. The 211 students had widely different cultural backgrounds, including Asian, South Pacific, Middle Eastern, European, and African countries. Among adolescents who were migrants to Australia, the prevalence of asthma symptoms was higher than that reported using a similar methodology in their country of origin. Asthma symptom prevalence was related to residence time in Australia. The prevalence of wheeze was 17.2% in recent arrivals, 20.5% in adolescents living in Australia for >2 years, and 36.3% in those living all their lifetime in Australia (P = 0.013). For every year of residence in Australia, there was an 11% increase in prevalence of current wheeze (odds ratio, 1.11; P = 0.02). This effect was not related to atopy, AHR, or eosinophilic airway inflammation. Sputum neutrophils were elevated in recent arrivals. In conclusion, adolescents who migrate to Australia report increased asthma symptoms, compared to their country of origin, and asthma symptoms are further increased for every additional year of residence in Australia. The development of wheeze after migration to Australia was independent of eosinophilic inflammation and consistent with noneosinophilic asthma mechanisms.

Association of an early respiratory syncytial virus infection and atopic allergy

BACKGROUND

Respiratory syncytial virus (RSV) causes postbronchiolitic wheezing but its role in allergic sensitization is controversial. The purpose of the study was to examine the effect of an early RSV infection on allergic sensitization.

METHODS

Seventy-six subjects were examined 6-10 years after hospitalization for RSV infection during the first year of life. Fifty-one subjects (68%) attended clinical studies and 25 filled in a questionnaire. The study protocol included lung function, skin-prick and blood tests. The controls were matched for birth date and sex.

RESULTS

Eight per cent of the subjects and 37% of the controls had at least one positive skin-prick test (SPT) (difference -35%, 95% CI -50 to -19%, P < 0.0001). Allergic rhinitis, atopic dermatitis and asthma occurred as often in both groups, but asthma had been diagnosed significantly earlier in the subjects than in the controls [mean age 3.0 years (SD 2.6) and 5.6 years (SD 3.0), difference 2.6 years, 95% CI 0.57-4.65, P = 0.014]. In a logistic regression analysis, RSV infection was associated with negative SPTs.

CONCLUSIONS

An early RSV infection results in reduction of SPT positivity but not of occurrence of atopic diseases. This finding might explain why there is less atopic sensitization in countries with a greater probability of acquiring RSV infection at an early age.

The relationship of health insurance to the diagnosis and management of asthma and respiratory problems in children in a predominantly Hispanic urban community

OBJECTIVES

As part of an asthma screening study, we evaluated the relationship of health care insurance coverage to the diagnosis and treatment of elementary school children for asthma and related respiratory problems from 1998 through 2001.

METHODS

A bilingual questionnaire assessing health care coverage, asthma diagnosis, respiratory symptoms, and use of medications was distributed to parents of 6235 public and private school children in grades 2 through 5 in Passaic, NJ.

RESULTS

Responses for 4380 children (70%) revealed disparities in health care coverage and asthma diagnosis among racial and ethnic groups. Mexican and Dominican children had significant increases in health care coverage over the 4 years.

CONCLUSIONS

The percentage of children with health insurance grew from 67% in 1998 to 81% in 2001, and the increase was related to NJ KidCare. Diagnosis of asthma and treatment were related to health care coverage.

Sequelae of severe respiratory syncytial virus infection in infancy and early childhood among Alaska Native children

OBJECTIVE

In 1993-1996, we conducted a nested case-control study to determine risk factors for hospitalization with respiratory syncytial virus (RSV) infection among Alaska Native infants and young children. In the current study, we returned to former RSV case-patients and their control subjects during 1999-2001 to determine whether children who are hospitalized with RSV at <2 years of age are more likely to develop chronic respiratory conditions.

METHODS

For each former RSV case-patient and control subject from remote villages in southwest Alaska, we reviewed medical records, interviewed parents, performed physical examinations and spirometry, collected sera, and analyzed chest radiographs. Case-patients were identified through surveillance for RSV hospitalization, and matched control subjects without lower respiratory infection (LRI)-related hospitalization were identified.

RESULTS

Hospitalization for RSV infection was associated with a significant increase in wheezing, LRIs, and asthma diagnosis during the first 4 years of life. The association decreased with age and was no longer significant by 5 years of age. However, hospitalization for RSV infection was associated with increased respiratory symptoms and increased chronic productive cough at 5 to 8 years of age. Children who were hospitalized with RSV were not more likely at follow-up to have allergies, eczema, or a positive family history of asthma.

CONCLUSIONS

Severe RSV infection in infancy may produce airway injury, which is manifested in chronic productive cough with or without wheezing and recurrent LRIs. Although the association of RSV infection with wheezing seems to be transient, children remain at higher risk for chronic productive cough at 5 to 8 years of age. RSV prevention modalities may prevent sequelae that occur early and later in childhood.

Predictive features for persistence of atopic dermatitis in children

Allergen exposure plays an important role in atopic dermatitis (AD). Because immunological mechanisms underlying asthma and AD have great similarities, we evaluated whether features such as allergen sensitization, immune response, disease severity and duration or allergen exposure could be considered predictive for AD persistence. Seventy-one AD children (age range 14-158 months) were enrolled and followed for 3 consecutive years for AD severity using the SCORAD index (SI). At enrollment, reactivity to inhalant and food allergens using the skin prick test (SPT) and house dust mite (HDM) atopy patch test (APT), and HDM allergens in house dust were evaluated. After 3 years, 38 children outgrew their AD (AD- group), while in 33 AD persisted (AD+ group). At enrollment, AD+ children had a higher SI, higher rate of positivity to SPT and APT for mites (p = 0.001), and higher environmental exposure to HDM allergens (p = 0.035). The AD+ children developed more respiratory symptoms in comparison to AD- children (p < 0.001). None of the AD- children presented APT positivity. In our study population, positivity of SPT and APT for HDM, environmental allergen exposure levels and severity of the disease at enrollment presented a significant predictive power towards AD persistence. Subjects with positive skin reactivity to HDM should be considered at risk of AD persistence and of possible development of allergic respiratory disorders.

Longitudinal follow-up of the changing gender ratio in asthma from childhood to adulthood: role of delayed manifestation in girls

Boys suffer more often from asthma than girls, while in adults the gender ratio is reversed. It is not clear when exactly this change occurs and by what mechanism. From a cohort of all 5030 German 4th grade pupils (age 10 years) in Munich, 274 children with current asthma were identified (164 males, 110 females) through a questionnaire, and skin prick tests were performed. These subjects were re-evaluated at ages 14 and 20 years with a questionnaire. A random sample (n = 1000) of all 3538 German children without current asthma at age 10 was also re-evaluated at age 20 (controls). At age 20, only 24.5% (21 males, eight females) of the initial asthma group still had symptoms, and their gender ratio remained male dominated. In the controls, 4.8% (48/1000) had current asthma at age 20 and these were predominantly female: 6.4% (31/485) of control girls vs. 3.3% (17/515) of boys (p = 0.022). Half of the new asthma cases had had no symptoms or diagnoses until age 10, and atopy at age 10 was not associated with subsequent asthma in these. Asthma at age 10 has no better prognosis in boys than in girls, and the mechanism of the changing gender ratio appears to be late incidence of asthma among girls. Because the latter constitute a considerable part of adult asthma cases, it appears important to further explore this asthma phenotype and the risk factors associated with it.

ISAAC-based asthma and atopic symptoms among Ha Noi school children

Childhood asthma and atopy prevalence patterns in the developing world are only beginning to be defined. No such information exists for Vietnam. Estimates would assist in anticipating health service needs as well as add to the growing database on global patterns of atopy. To estimate the prevalence of atopic symptoms in school children in Ha Noi, Vietnam, a cross-sectional survey was conducted of children aged 5- to 11-years-old in two schools using the parent self-administered International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. The response rate was 66.4% (969 responses). The overall prevalence of selected symptoms were: 'ever wheezed' 24.9%, 'wheezed in past 12 months' 14.9%, 'ever had asthma' 12.1%, 'doctor-diagnosed asthma' 13.9%, 'ever experienced allergic rhinitis (AR) symptoms' 34.9%, 'AR-conjunctivitis symptoms in past 12 months' 10.7%, 'ever had hay fever' 7.8%, 'doctor-diagnosed hay fever' 11.2%, 'ever had eczema' 3.3% and 'doctor-diagnosed eczema' 3.2%. Kappa statistics demonstrated high within symptom category consistency for 'ever had asthma/doctor-diagnosed asthma' (0.728) and 'ever had eczema/doctor-diagnosed eczema' (0.906). Age and gender adjusted odds ratios (OR) were also consistently significant across wheeze and allergic rhinitis symptom categories [highest OR = 10.10 (95% CI 6.23-16.35) between allergic rhinoconjunctivitis and wheeze in past 12 months]. There is a high prevalence of ISAAC-based symptoms in school children in Ha Noi, Vietnam, often above global averages. The high level of association between atopic symptoms suggests some degree of reliability and validity. Childhood atopy symptom prevalence in Vietnam is more similar to that in developed countries rather than developing countries.

Epidemiologic evidence of a relationship between airway hyperresponsiveness and exposure to polluted air

BACKGROUND

There has been an increase in allergic diseases as a result of increased air pollution emanating from traffic and various industries.

OBJECTIVE

This study evaluated the association between air pollution and airway hyperresponsiveness in a cross-sectional study of a cohort of 670 children, aged 10-13 years.

METHODS

We measured spirometry and conducted allergic skin tests and methacholine challenge tests in 670 schoolchildren. The methacholine concentration causing a 20% fall in FEV1 (PC20) was used as the threshold of airway hyperresponsiveness (AHR). Thresholds of 16 mg/dl or less were assumed to indicate AHR.

RESULTS

All of the schoolchildren had normal pulmonary function. Of the children, 257 (38.3%) had AHR. There was a significant increase in AHR in schoolchildren living near a chemical factory [45.0% (138/306), 6.50 +/- 0.48] compared to those in rural [31.9% (52/163), 9.84 +/- 0.83] and coastal [33.3% (67/201), 7.17 +/- 0.68] areas. Atopy was significantly more prevalent near the chemical factory vs the coastal and rural areas [35.6% (109/306) vs 27.3% (55/201) and 23.3% (38/163), respectively, P < 0.007]. Schoolchildren with atopy had lower PC20 than those without atopy (5.98 +/- 0.60 vs 8.15 +/- 0.45, P < 0.001). Positive allergy skin tests and living in a polluted area were risk factors in multivariate analyses adjusted for sex, parents' smoking habits, age, body mass index, nose symptoms and lung symptoms (odds ratio for location = 2.4875, confidence interval 1.6542-3.7406, P < 0.000; odds ratio for allergy skin test = 1.5782, confidence interval 1.1130-2.2379, P < 0.0104).

CONCLUSION

Our findings demonstrate that more children living in polluted areas have airway hyperresponsiveness than do those living in less polluted areas.

Tidal off-line exhaled nitric oxide measurements in a pre-school population

Exhaled nitric oxide (ENO) is used as a non-invasive marker of airway inflammation. The aim of this study was to measure ENO in a pre-school population using a relatively novel method, the off-line tidal breathing method, and to investigate differences in ENO between subjects with different presentations of wheezing. ENO was measured in 129 children (median age 4.4 years, quartiles 4.0-4.8 years) through a mouth mask attached to a two-way valve with an expiratory resistance of 5 cm H(2)0. Mean tidal ENO concentration (tENO) was calculated from triplicate measurements. Mean +/- SEM tENO for 89 control subjects was 13+/-0.4 ppb (95%CI 11.8-13.7 ppb); this level was significantly different from tENO in 15 children with a history of recurrent wheezing (18.6+/-1.9 ppb; 95%CI 14.5-22.7 ppb; t-test P<0.0001). Mean tENO in 16 children with a single wheezing episode was 11.4+/-1.0 ppb (95%CI 9.2-13.6 ppb) and thus significantly different from the recurrent wheezing group (t-test P=0.0024).

CONCLUSION

The off-line tidal breathing method is a feasible and appealing method for measuring exhaled nitric oxide in pre-school children. With this method, higher tidal exhaled nitric oxide levels were found in children with recurrent wheezing.

Assessment of the diagnosis and prevalence of asthma in Australian indigenous children

BACKGROUND AND OBJECTIVE

Although the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire has been used in many countries and has been validated previously, it has not been used in Australian Indigenous communities. We endeavoured to assess its performance when administered in Aboriginal and Torres Strait Islander communities.

METHODS

In a cross-sectional study, we assessed the ISAAC's questionnaire when administered face-to-face in Indigenous communities in the Torres Strait region, Australia.

RESULTS

Comparing responses to the questionnaire with clinical assessment of 260 Indigenous children by a pediatric respiratory physician, sensitivity (87%) was high, but specificity (51%) and positive predictive value (33%) were low. Using a logistic regression model, we determined which questions were most useful in predicting a clinical diagnosis of asthma. Using a predictive equation, asthma was detected with 79% sensitivity and 77% specificity, and the calculated weighted estimate of asthma prevalence in the region was 16.3%.

CONCLUSION

Our findings reveal that although the ISAAC questionnaire is a reasonably sensitive tool for both epidemiologic and clinical studies of asthma in Indigenous communities, its value is enhanced when used in conjunction with a predictive model. We have also shown that asthma is prevalent in the Torres Strait region.

Are asthma and allergies in children and adolescents increasing? Results from ISAAC phase I and phase III surveys in Münster, Germany

OBJECTIVE

To assess time trends in symptoms of asthma, allergic rhinitis, and atopic eczema among children in Münster, Germany.

METHODS

Two cross-sectional surveys 5-years apart (1994/1995, 1999/2000) using ISAAC core written and video questionnaires and applying the ISAAC protocol. Two main age groups (6-7 and 13-14 year olds) were designated with information collected by parental and self-report for both age groups, respectively. A school-based sample of 7744 participants in the 1994/1995 survey and 7962 participants in the 1999/2000 survey was recruited. In the first and second surveys, response rates for the 6-7 year olds were 81 and 82%, respectively, while for the 13-14 year olds response rates were 94% in both. Analyses focus on the change in 12-month prevalence of symptoms of asthma, rhinitis, and eczema.

RESULTS

There is a tendency towards an increase in current symptoms for all three conditions and in both age groups, but more so among girls. Indices of diagnosis either remained the same or increased in parallel to the increase in symptoms. Indices of severity also showed a homogenous increase in the 5-year study period.

CONCLUSIONS

Our study shows that symptoms of asthma, rhinitis, and eczema are increasing, reflecting a change in the morbidity of these conditions in our population.

Atopic eczema in early childhood could be protective against Type 1 diabetes

AIMS/HYPOTHESIS

According to the Th1/Th2 paradigm Type 1 diabetes and atopic diseases are assumed to be mutually exclusive on the individual level. We analysed the association between Type 1 diabetes and atopic diseases in a case-control design in order to test the hypothesis that atopic diseases in early childhood could protect against Type 1 diabetes.

METHODS

We carried out a nationwide population-based case-control study enrolling 760 cases newly-diagnosed with Type 1 diabetes under five years of age between July 1992 and December 1995 and 1871 controls randomly selected from the general population and individually matched on sex, age and place of residence. Information on atopic diseases was obtained by a mailed parent-administered questionnaire. Data were analysed by multivariate logistic regression adjusting for potential confounders (family history of diabetes, social status, duration of overall breast feeding, number of children in family, maternal age at delivery).

RESULTS

Atopic eczema was less frequent in diabetic (13.3%) than in non-diabetic children (18.0%) and was significantly associated with a reduced risk of Type 1 diabetes. The adjusted odds ratio was 0.71 (95% CI 0.53-0.96). Hay fever and asthma were not significantly associated with diabetes risk (OR 0.98 (95% CI 0.47-2.01) and 1.46 (95% CI 0.70-3.06), respectively).

CONCLUSION/INTERPRETATION

In this large population-based case-control study in pre-school children an inverse association was observed between atopic eczema and Type 1 diabetes. Thus, in accordance with the Th1/Th2 paradigm development of atopic eczema in early childhood could be protective against childhood Type 1 diabetes.

Prevalence of symptoms of asthma and allergies in schoolchildren in Gondar town and its vicinity, northwest Ethiopia

A low level of allergic disorders has been generally reported in children from developing countries. A survey was conducted to determine the prevalence of symptoms of asthma and allergies among schoolchildren in Gondar, northwest Ethiopia. A standardized self-administered questionnaire developed by the International Study of Asthma and Allergies in Children (ISAAC) was used. In total, 3,365 children aged 13-14 years were surveyed at school, with a response rate of 98.4%. The female to male ratio was 1.5:1. The 12-month-period prevalences of wheeze (16.2%), rhino-conjunctivitis (14.5%), and eczema (10.9%) were comparable to findings from Addis Ababa, but significantly higher than reported from Jimma. A striking seasonal pattern of rhinitis symptoms is observed during the months of September-December with a peak in November, corresponding with the main pollen season of the area. Overall, about 36% of the children reported symptoms of atopic disorders. However, the prevalence of diagnosed atopic diseases (8.6%) is less than a quarter of the symptom prevalence rate. This may reflect a generally poor awareness and low health service utilization, or underdiagnosis by health facilities. In conclusion, it appears that the prevalence of atopic diseases in Gondar area is high, and there is also wide variation within the country. This calls for further epidemiological studies with more objective assessments of atopy, such as allergen and bronchial hyperresponsiveness tests and ecological analysis.

International patterns of the prevalence of pediatric asthma the ISAAC program

Like so much research, the findings from the ISAAC program have raised more questions than they have answered. Despite their limitations, the ISAAC findings provide the basis for further studies to investigate factors that potentially contribute to these international patterns and may lead to novel public health and pharmacologic intervention strategies that reduce the prevalence and severity of asthma worldwide.