Lung function growth and ambient ozone: a three-year population study in school children

We followed a cohort of 1,150 children for 3 yr to investigate long-term effects of ambient ozone. Nine study sites were selected on the basis of air-quality data to represent a broad range of ozone exposure. In 1994, 1995, and 1996 lung function was recorded biannually, always before and after summertime. The effect of ozone was analyzed with regression analyses and study-site, a child's sex, atopy, passive smoking, baseline lung function, and increase in height were considered as confounding variables. A negative effect of summertime ozone on the pre- to post-summer-time change in FEV(1) (ml/d) was present in 1994 (beta = -0.019 ml/d/ppb; p < 0.01) and in 1995 (beta = -0.017 ml/d/ ppb; p < 0.05), but not in 1996 (beta = 0. 004 ml/d/ppb; p = 0.6); corresponding estimates for FVC were in 1994: beta = -0.022 ml/d/ppb, p < 0.005; 1995: beta = -0.018 ml/d/ppb, p < 0.05; and 1996: beta = 0.006 ml/d/ppb, p = 0.46. When all three study years were considered simultaneously, i.e., the changes in lung function between each of two subsequent surveys being the dependent variable, summertime ozone was associated with a lesser increase in FEV(1) (beta = -0.029 ml/d/ppb; p < 0.001), FVC (beta = -0.018 ml/d/ppb; p < 0.001), and MEF(50) (beta = -0.076 ml/s/d; p = 0.001). No consistent associations were observed for lung function and NO(2), SO(2) and PM(10). Long-term ambient ozone exposure might negatively influence lung function growth.

Lack of relationship between eosinophil cationic protein and eosinophil protein X in nasal lavage and urine and the severity of childhood asthma in a 6-month follow-up study

BACKGROUND

Recent studies suggest that eosinophil cationic protein (ECP) and eosinophil protein X (EPX) may be valuable markers of airway inflammation in various body fluids of asthmatic children. Most of these studies have relied on a single measure of inflammatory markers.

OBJECTIVE

We measured ECP and EPX in nasal lavage fluids (NALF) and urine samples in children with asthma over a 6-month period to study the relationship between inflammatory markers and clinical severity.

METHODS

Fourteen children with mild persisting asthma (mean age 11.7 years, SD 2.2) were recruited. All patients were on therapy including inhaled steroids. For a 6-month period asthma severity was monitored by at least monthly physical examination and pulmonary function tests. Daily morning and evening PEF, asthma symptoms and medication were recorded in diaries for the whole study period. Telephone interviews were performed between visits and additional visits were done in case of an increase in asthmatic symptoms or drop of PEF values under 80% of best value. An exacerbation was defined by a fall of FEV1 > 10% and an increase in asthma symptoms and additional need of beta2-agonist. NALF and urine samples were obtained at each visit and analysed for ECP (NALF only) and EPX.

RESULTS

Mean observation time was 186.4 days (SD 19.8). Thirteen patients completed the study. During the study period 11 exacerbations were observed in six patients. No significant associations between PEF, PEF variability (amplitude % of mean), daily symptoms, additional beta2-agonist, FEV1 and MEF50 and nasal ECP, nasal EPX and urinary EPX were found. However, at exacerbations an average increase of nasal ECP (9.3 vs 50.3 microg/L) and EPX (nasal EPX 36.4 vs 141.7 microg/L, urinary EPX 46.4 vs 74.1 microg/mmol creatinine) was observed.

CONCLUSION

Serial measurements of ECP and EPX in NALF and urine samples do not provide additional information for the practical management in monitoring childhood asthma.

Assessment of eosinophil granule proteins in various body fluids: is there a relation to clinical variables in childhood asthma?

BACKGROUND

The eosinophil plays a central role in the inflammatory process in bronchial asthma. Recent studies have indicated that the assessment of eosinophil-derived proteins in various body fluids could be used for monitoring disease activity of childhood asthma. Till now, no study exists which compared the levels of eosinophil-derived proteins in various body fluids such as serum, nasal lavage fluid (NALF) and urine.

OBJECTIVE

To investigate whether eosinophil granule proteins in different compartments were correlated and whether there is a relationship between disease activity, pulmonary function and bronchial hyperreactivity.

METHODS

Twenty-eight children with atopic bronchial asthma were recruited. Serum, NALF and urine samples were obtained and assessed for eosinophil cationic protein (ECP) and eosinophil protein X (EPX). The levels of eosinophil proteins were analysed for a relationship with lung function variables, bronchial hyperreactivity and disease activity. Eleven healthy control subjects were used as controls.

RESULTS

Median ECP and EPX concentrations in serum (31.4 and 74.8 microg/L vs 15.8 and 24.3 microg/L, respectively), NALF (9.9 and 44. 9 microg/L vs 0 and 2.5 microg/L, respectively) and urine (49.4 vs 16.5 microg/mmol creatinine) were significantly raised in children with bronchial asthma compared with healthy control subjects. In addition, ECP and EPX levels in serum and urine samples were significantly higher in symptomatic patients compared with asymptomatic subjects with asthma. Although no relationship between eosinophil-derived proteins in serum, NALF or urine and the level of nonspecific bronchial hyperreactivity could be detected, the concentrations of EPX in serum and urine were correlated with variables of pulmonary function.

CONCLUSION

Our findings demonstrate increased eosinophil activity in serum, NALF and urine derived from children with bronchial asthma. Due to the relationship between levels of eosinophil proteins in serum/urine samples and lung function, as well as significant concentration differences between symptomatic and asymptomatic asthmatic children, the assessment of eosinophil proteins in serum or urine samples appear to be more appropriate in monitoring disease activity than measurement of ECP or EPX in NALF. Thus, the determination of serum ECP/EPX or urinary EPX may be preferentially used in monitoring eosinophilic inflammation in childhood asthma.

Comparison between serial skin-prick tests and specific serum immunoglobulin E to mite allergens

Sensitization to dust mite allergens can be determined by means of a skin-prick test (SPT) or by measurement of specific IgE antibodies in serum (sIgE). In our study, concordance of the results of both methods was analyzed on the basis of reproducible SPT results. Three consecutive SPTs were performed on 138 school children (age 6-8 years) at one-year intervals. SIgE was determined at the end of a two-year observation period. Seven common inhalant allergens (Dpt, Df, birch pollens, hazel pollens, grass pollens and cat and dog dander) were analyzed. The majority of subjects with positive SPT reactions to the respective allergen also showed sIgE (Dpt: 82/86; Df: 53/53; cat dander: 31/32; dog dander: 6/9; birch pollens: 29/31; hazel pollens: 22/22; grass pollens: 37/37). A significant correlation between the SPT [weal diameter (P1) or allergen/ histamine ratio (P2)] and sIgE was found for Dpt (P1 = 0.004/ P2 = 0.016), birch pollens (P1 = 0.002/P2 = 0.0001) and grass pollens (P1 = 0.0005/P2 = 0.0001). There was also a significant correlation between sIgE to Dpt and to either Der p 1 (p = 0.0001) or Der p 2 (p = 0.0001), as well as between sIgE of both major allergens (p = 0.0001). In the analysis of co-sensitization of Dpt and Df, most subjects sensitized to Dpt were also sensitized to Df (57/91). Children with sIgE to Dpt (n = 87) usually showed sIgE to Df(n = 83). In this study, SPT and sIgE results are concordant and appear equivalent when using reproducible SPTs. Therefore, in the case of a positive Dpt result, additional testing for sensitization to Df can be regarded as redundant when Dpt and Df are the major contributors to the allergen content of house dust.

Necrotizing sarcoid granulomatosis in a 14-yr-old female

A case of a 14-yr-old female with necrotizing sarcoid granulomatosis (NSG) is presented. She was referred because of chest pain and malaise, and radiography revealed multiple pulmonary nodules. Her history showed seasonal sensitization to aeroallergens and hay fever. Infectious agents or malignancies did not characterize these nodules. However, she was treated with macrolide antibiotics because of suspected infection with Chlamydia pneumoniae. Open lung biopsy showed histological findings of NSG, with epithelioid granulomatous inflammation, including giant cells, and vasculitis. No further treatment was performed, and symptoms disappeared within a few weeks. The chest radiograph showed gradual improvement. The aetiology of NSG is poorly understood, and is postulated to represent either sarcoidosis or rare forms of pulmonary vasculitis such as Wegener's granulomatosis or the Churg-Strauss syndrome. In the case presented, a coincidence of infection with Chlamydia pneumoniae suggests an involvement of infectious agents in the pattern of formation of immune complexes in the aetiology of NSG.

Accumulation of atopic disorders within families: a sibling effect only in the offspring of atopic fathers

BACKGROUND

Several studies have reported an association between a child's risk of atopic disorders and family size. However, the inverse association might not be the same in populations with a different genetic disposition for atopic disorders.

OBJECTIVE

This longitudinal study was designed to assess risk factors of atopy.

METHODS

Lifetime prevalence of asthma, hay fever and eczema of 1440 families including 3165 offspring was ascertained by means of standardized questionnaires.

RESULTS

After possible confounders had been controlled for, an inverse association between atopic disorders and the number of older siblings was found only in the offspring of atopic fathers (trend for older siblings: chi2 = 13.38, degrees of freedom [d.f.] = 1, P= 0.0002; odds ratio 'no older sibling'= 2.87 (95% confidence interval 2.18-3.78); '1 older sibling' = 2.11 [1.52-2.92], '2 older siblings' = 1.29 [0.74-2.23]; '3 or more older siblings' = 0. 15 [0.02-0.981). No such relationship was found for children without a history of paternal atopy (trend for older siblings: chi2 = 1.5 1, d.f. = 1, P = 0.22; odds ratio 'no older sibling' = 1 [reference]; '1 older sibling' =0.82 [0.63-1.06]; '2 older siblings' = 0.97 [0.67-1.40]; '3 or more older siblings' = 0.64 [0.31-1.33]). The trend for older siblings in the case of paternal atopy was significantly different from the trend for older siblings without a history of paternal atopy (chi2 = 8.68, d.f. = 1, P = 0.003). The number of younger siblings was not related to child's risk of atopy (trend for younger siblings: chi2 = 0.001, d.f. = 1, P = 0.97).

CONCLUSIONS

Data from this study suggest a protective effect of sibship size only in children with a history of paternal atopy and if older siblings are present. The reason for this combined effect remains unclear. Thus, further investigations are needed to interpret the biological cause of the so called 'sibling effect'.

Cotinine excretion as a predictor of peak flow variability

Environmental tobacco smoke (ETS) is suspected to be an important risk factor for bronchial hyperresponsiveness. In order to test the effect of ETS, we measured expiratory flow rates and urine cotinine excretion (UCE) within a narrow time window in two consecutive years. Maternal smoking habits and medical history were ascertained by standardized questionnaires. The percentage ratio of the amplitude over the mean (AVAM) of the diurnal peak flow rates of children (complete values from at least five consecutive days) was calculated as an indicator of bronchial responsiveness. The association of UCE and log10AVAM was analyzed by multiple linear regression. Complete data were available for a sample of 417 children. The median of UCE in children of parents who smoked (3.2 ng/mg and 2.9 ng/mg creatinine, Surveys 1 and 2, respectively) was higher than the median in children of nonsmoking parents (0 ng/mg in both surveys). With increasing UCE the log10AVAM rose in the first and second surveys, as well as in the longitudinal analysis (p = 0.003). This association, however, showed up only in boys (p = 0.0001) and not in girls (p = 0.31). Our data suggest that there is a need both for further analysis of the gender difference and for more support of strategies against passive smoking as far as children are concerned, since airway hyperresponsiveness is a risk factor for chronic airway impairment.

Longitudinal predictors of airway responsiveness to distilled water: the role of atopy and maternal smoke exposure

Airway responsiveness is an objectively measurable clinical trait related to the presence of asthma. Although risk factors for this trait have been evaluated cross-sectionally, little is known about its longitudinal predictors. A population cohort of 539 children, aged 8 yrs at the start of follow-up, underwent 3-7 bronchial challenge tests spaced at 3-9 month intervals. Airway responsiveness was assessed by a single-step distilled water challenge. To investigate responsiveness as a continuous trait, the ratio of the postchallenge to prechallenge forced expiratory volume in one second was calculated. A child's repeated ratios were then regressed on the time of follow-up. The resulting child-specific regression coefficient was the outcome variable to assess longitudinal predictors of airway responsiveness (AR). Results were based on 2,267 repeated challenge tests, and indicated an overall decrease in responsiveness. Children with a diagnosis of asthma (mean+/-SD, longitudinal change in AR + yr(-1): -0.060+/-0.149), those with a positive skin-prick test (-0.018+/-0.106) and those with reported exposure to maternal smoking (-0.004+/-0.083) demonstrated increased airway responsiveness over time. All of these changes in airway responsiveness were found to be significant in multiple linear regression analysis (p<0.05). Stratified analysis further indicated that the effect of maternal smoking was observed primarily in nonatopic children and was greatest at an exposure level of > or =10 cigarettes x day(-1). In conclusion, atopy and exposure to maternal smoking can predict longitudinal change in childhood airway responsiveness.

Determinants of reproducibility of lung function tests in children aged 7 to 10 years

Lung function (LF) tests are part of many investigations in childhood lung disease. However, individual reproducibility of LF will confound between-subject differences. At the same time, increased LF variability has been linked to respiratory disease. In a sample of 598 children, two LF tests, separated by a 5-min interval, were recorded, and reliability (Rel) of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and maximal expiratory flow at 50% of FVC (MEF50) was determined. Rel was also assessed in children trained and untrained in the performance of LF. To investigate determinants of reproducibility for FEV1, the absolute difference between two repeated tests was calculated. Whenever this difference was > 120 ml, a child was considered to demonstrate excessive variability (poor reproducibility) in FEV1. For volume parameters coefficients of reliability (Crel) were found to be better than for MEF50 (FEV1: 0.96; FVC: 0.94, MEF50: 0.91). In untrained children Crel for FEV1 was only 0.91, but it was increased in subsequent visits (0.98, 0.97, and 0.97 at the second, third, and fourth tests, respectively). Excessive variability in FEV1 was observed in 10% of children and was related to the presence of wheeze [odds ratio (OR) 6.31; 95% confidence interval (CI) 1.78-22.4), shortness of breath (OR 3.14; 95% CI 1.00-9.93), a diagnosis of asthma (OR 6.25; 95% CI 1.76-22.1), and bronchial hyperresponsiveness (OR 4.30; 95% CI 2.07-8.94). We conclude that increased variability of LF is likely to be present in young children not accustomed to the testing procedure and in children with respiratory symptoms. Therefore, before guidelines for LF testing are applied, children should be trained to perform the tests and we should be cautious in the interpretation of test results in children who present with symptoms.

Cord blood mononuclear cells and milk-specific T-cell clones are tools to evaluate the residual immunogenicity of hydrolyzed milk formulas

BACKGROUND

Hydrolyzed milk formulas (HFs) are given to infants allergic to cow's milk proteins and, for preventive reasons, to atopy-prone newborns for which breast feeding is not feasible. The ultimate properties of HFs are not only a reduced allergenicity but also decreased immunogenic capacity combined with good taste and caloric value. No information is available concerning the capacity of HFs to induce immune responses.

OBJECTIVE

We sought to determine the residual immunogenic capacity of partially (pHF) and extensively hydrolyzed milk formula (eHF), and we studied the cellular reactivity of cord blood-derived (n = 71) mononuclear cells induced by 10 different HFs.

METHODS

To test the effect of HF on T-helper cells, beta-casein-specific T-cell clones (TCCs, n = 21) from individuals allergic to milk were established, and T-cell proliferation and cytokine profiles (interferon-gamma and IL-4) were determined on stimulation with HF.

RESULTS

We found significantly reduced proliferative responses of eHF compared with milk proteins. Whey-based pHF displayed the same proliferative capacity as unmodified milk proteins. As expected, extensively processed whey products displayed lower cellular responses compared with partially hydrolyzed products (pHF whey vs eHF whey, p < 0.0001). No difference in cellular response was found between casein-based pHF and casein-based eHF. Beta-casein-specific TCCs (n = 21) proliferated in response to casein-derived hydrolysates (14% with casein/whey-based pHF, 4% with casein-based pHF, and 0% with casein-based eHF). Whey-based pHF was also found to induce proliferation in beta-casein-specific TCCs, indicating the presence or the generation of peptides displaying cross-reactivity with these whey-derived hydrolysates. TCCs stimulated with whey- or casein-based pHF or eHF produced the same amount of cytokines (IL-4, interferon-gamma) as the same clones stimulated with unmodified products.

CONCLUSION

Our data indicate that whey- and casein-derived eHFs display highly reduced immunogenic properties at the T-cell level. In contrast, pHFs display residual immunogenic properties detectable at the T-cell level, reflecting a potential for the induction of pathogenetically important T-cell responses.

Determinants of eosinophil cationic protein in nasal lavages in children

BACKGROUND

Nasal lavages are increasingly used to assess airways inflammation in children. However, there are no studies assessing how measurement error as well as biological influences contribute to the concentration of nasal inflammatory parameters in a population based survey.

OBJECTIVE

To investigate determinants of concentration of eosinophil cationic protein (ECP) in nasal lavages we studied 147 schoolchildren (mean age 8.1 years, SD 0.6 years) by repeated nasal lavages/year over a 2 year period.

METHODS

Standardized questionnaires were completed by the parents each year. A skin-prick test with seven aeroallergens (birch, cat, dog, hazel, weeds, Dermatophagoides pteronyssinus and D. farinae) was performed. One hundred and one children could perform valid lavages at least five times a year. As a measure of reproducibility the intraclass coefficient of reliability was calculated.

RESULTS

The intraclass coefficient of reliability was 0.27 over all observations suggesting that about a quarter of total variance is due to between-subject variance. Taking means over each year increased reliability to 0.60. Linear regression analyses with ECP being the dependent variable demonstrated significant higher values for boys (beta=12.26; P < 0.01), children sensitized to seasonal (beta=34.27; P=0.02) but not to perennial allergens (beta=-4.44; P=0.57), and for children with a serous (beta=10.01; P=0.01) or purulent rhinitis (beta=22.45; P < 0.001).

CONCLUSION

Assessment of inflammatory mediators in nasal lavages is a useful tool for epidemiological paediatric studies. However, due to the relatively high intraindividual variability of ECP concentrations multiple lavages are necessary to characterize the individual.

Traffic-related NO2 and the prevalence of asthma and respiratory symptoms in seven year olds

The aim of this study was to determine whether outdoor nitrogen dioxide (NO2) was associated with the prevalence of asthma and respiratory symptoms. In eight nonurban communities, 843 children resident for a minimum of 2 yrs were studied. Since industrial sources of air pollution were at least 20 km away from the study communities, NO2 was considered to primarily indicate traffic-related air pollution. NO2 was recorded at central monitors, and the 3 yr mean exposure was calculated. Asthma and respiratory symptoms were assessed according to the International Study on Asthma and Allergy in Childhood. Prevalence of asthma at some time ("ever asthma") was associated with long-term NO2. In parallel with increasing levels of NO2 (community specific 3 yr mean 6.0-17.0 parts per billion (ppb)), asthma prevalence was 2.5, 1.4, 1.6, 2.3, 3.4, 3.6, 7.6 and 8.5%, respectively (p=0.002 for trend). The prevalence odds ratios (PORs) for "ever asthma", following adjustment for gender, age, parental education, passive smoke exposure, type of indoor heating, and parental asthma, were 1.28 (95% confidence interval (95% CI) 0.20-7.98), 2.14 (95% CI 0.40-11.3) and 5.81 (95% CI 1.27-26.5), when each of two communities with low, regular and high NO2, respectively, were compared with the two communities with very low NO2. For symptoms "wheeze" (adjusted PORs for increased NO2: 1.47, 1.23 and 2.27) and "cough apart from colds" (adjusted PORs for increased NO2: 1.49, 1.93 and 2.07), a similar trend was seen. In this study a significant relationship was observed between traffic-related nitrogen dioxide and the prevalence of asthma and symptoms. Whether this association is causal has to be tested in longitudinal studies.

Monitoring of disease activity by measurement of inflammatory markers in atopic dermatitis in childhood

Serum levels of soluble interleukin-2 receptor (sIL-2R), intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule (ELAM-1), and eosinophil cationic protein (ECP) were measured in 20 patients with atopic dermatitis before and after 4 days' treatment with prednisolone p.o. as well as in 16 healthy, nonatopic controls. Before steroid treatment, patients with atopic dermatitis demonstrated significantly higher serum levels of sIL-2R, ICAM-1, and ECP than healthy controls (P < 0.001), whereas ELAM-1 levels were not different between the groups. After 4 days of steroid treatment, clinical improvement was associated with a decrease of sIL-2R (P < 0.003), ICAM-1 (P < 0.004), and ECP serum levels (P < 0.003), but ELAM-1 levels remained unchanged. Both serum ECP and sIL-2R levels were significantly correlated with disease severity before as well as after steroid treatment. Changes of sIL-2R concentrations were strongly related to the changes of ECP levels. In addition, changes of serum sIL-2R and ECP levels in percentage were correlated with clinical improvement. These results indicate that the determination of sIL-2R and ECP serum levels may be useful in monitoring disease activity in atopic dermatitis in childhood, especially in treatment trials.

High levels of eosinophil cationic protein in wheezing infants predict the development of asthma

BACKGROUND

In association with respiratory tract infections, infants may have episodes of wheezing, which represent the onset of asthma in some of them. Activated eosinophils play a central part in asthmatic inflammation.

OBJECTIVE

We investigated whether, in infants experiencing their first episode of wheezing, eosinophil activation is present and can predict the development of asthma.

METHODS

In a prospective trial, eosinophil activation was measured by eosinophil cationic protein (ECP) concentrations in serum from 33 nonatopic infants with their first episode of wheezing, 15 nonatopic infants with upper respiratory tract infection without wheezing, and 18 healthy nonatopic infants. One year later, the children were re-evaluated for a diagnosis of infantile asthma.

RESULTS

Wheezing infants had higher median serum ECP levels (13.4 micrograms/L) than children with nonwheezy respiratory tract infection (7.6 micrograms/L, p < 0.005) or healthy subjects (7.1 micrograms/L, p < 0.005). In addition, wheezing infants (n = 13) with serum ECP concentrations greater than 20 micrograms/L were more likely to have asthma within 1 year than patients with ECP levels less than 20 micrograms/L (odds ratio = 12.4; confidence interval, 4.6-33.5).

CONCLUSION

Eosinophil activation measured by serum ECP is present in infants with their first episode of wheezing illness, especially in those infants in whom asthma subsequently develops within 1 year. These data may indicate a predictive value of serum ECP measurements in children with wheezing to identify those patients in whom infantile asthma is developing. These findings probably also indicate that serum ECP may be used to identify the children who need early antiinflammatory treatment.

Sensitization to Aspergillus fumigatus and lung function in children with cystic fibrosis

Colonization with Aspergillus fumigatus (Af) constitutes a common finding in children with cystic fibrosis (CF). The relationship between sensitization to Af and lung functon (LF) was studied in 118 patients with CF (61 girls and 57 boys; mean age: 14.3 yr; SD: 7 yr). Mean follow up was 2.2 yr. On average, 8.1 (SD: 4.8) LF tests were performed per patient. Measurement of total IgE and specific IgE antibodies to Af, and a skin prick test (SPT) for Af, were done once a year. Thirty-one children (26%) were sensitized to Af. On average, LF parameters were not significantly different in Af-sensitized children than in nonsensitized children. Linear regression analyses were performed, using the repeated measures design. With adjustment for gender, age, height, and weight, sensitization to Af was associated with lower values of FEV1 (beta = -0.209; p < 0.05) and FEF(25-75) (beta = -0.356; p < 0.01). Analysis of different subgroups of sensitization demonstrated the effect on LF only in Af-sensitized patients with elevated total IgE levels, and not in Af-sensitized patients with normal IgE levels. Furthermore, there was evidence for a more rapid decline in LF for Af-sensitized patients with elevated total IgE levels than in those with normal IgE levels. We conclude that sensitization to Af in the presence of increased IgE values is associated with lower LF values in children with CF.

Effects of ambient ozone exposures during the spring and summer of 1994 on pulmonary function of schoolchildren

To investigate the effect of natural exposure to ambient ozone over time, a follow-up study of school-aged children was performed in two small towns in southwestern Germany (Freudenstadt and Villingen) between March and October of 1994. Ozone half-hour mean concentrations were measured continuously and pulmonary function was tested in each child on four occasions (April, June, August, and September). To obtain an average short-term ozone effect, we first analyzed the data from the four time points separately and then constructed a model that included all information. During the study period the median (5th to 95th percentile) of all half-hour values of the ozone concentration was 101 micrograms/m3 or 50.6 ppb (45-179 micrograms/m3 or 22.5-89.8 ppb) in Freudenstadt and 64 micrograms/m3 or 32.1 ppb (1 to 140 micrograms/m3 or 0.5-70.1 ppb) in Villingen. To assess the effects of an individual ozone exposure we related the highest ozone concentration in the respective 24 hours before lung function testing to the results of the subconcentration in the respective 24 hours before lung function testing to the results of the subsequent pulmonary function tests. In the lung function test following the highest ozone exposure, the results of our cross-sectional linear regression analysis showed a significant negative correlation (P = 0.0181) between ozone exposure and forced vital capacity (FVC). In the longitudinal linear regression model we observed a negative statistical correlation between ozone exposure and lung function for the subpopulation living in the town with the high ozone levels (Freudenstadt). The association was more pronounced in boys than girls. For the children in Freudenstadt the decrement of FVC was -12.31 ml/10 micrograms/m3 ozone and the decrease in the forced expiratory volume in 1 second (FEV1) was -11.29 ml/10 micrograms/m3 ozone.

Urinary eosinophil protein X in relation to disease activity in childhood asthma

The clinical use of urinary eosinophil protein X (U-EPX) measurements in monitoring inflammation in childhood asthma was investigated. U-EPX and pulmonary function were assessed in 80 children with bronchial asthma and 24 healthy, age-matched controls. In addition, 14 patients with asthma were re-examined after 1-2 months. U-EPX levels were increased in children with asthma compared with controls (median 68.4 vs 35.3 micrograms/mmol creatinine; P < 0.0001). In addition, U-EPX levels were higher in symptomatic than in asymptomatic patients (median 123.5 vs 48.9 micrograms/mmol creatinine; P < 0.0001) independent of treatment modalities (i.e., inhaled steroids or disodium cromoglycate) or atopy (median 65.1 vs 86.0 micrograms/mmol creatinine). Furthermore, U-EPX levels were significantly correlated with pulmonary function. During the follow-up period, changes in U-EPX values were significantly related to changes in pulmonary function. In conclusion, our findings demonstrate that eosinophil activation can be measured in urine in childhood asthma. Concentrations of U-EPX are related to disease activity and pulmonary function, as shown in both cross-sectional and longitudinal analyses, but are independent of atopy and treatment modalities. Measurement of U-EPX may be useful in assessing the inflammatory process and therefore in the management of childhood asthma.

The internal dose of passive smoking at home depends on the size of the dwelling

As part of a longitudinal study two urine samples (survey 1 in 1991 and survey 2 in 1992) were collected from 602 elementary school children to investigate the relationship between urinary cotinine excretion (UCE) and the daily consumption of cigarettes at home (exposure). Size of the dwelling, educational level, and maternal smoking were taken into consideration as additional predictors. The history regarding parental smoking habits and confounding variables was ascertained by standardized questionnaires completed by the parents. Cotinine was measured using gas chromatography selected ion monitoring. UCE was expressed as cotinine/creatinine (ng/mg). In children with detectable UCE in survey 1 (35%) and in survey 2 (44%) the excretion ranged between 1.5 and 24.7 ng/mg (5-95%) and between 1.2 and 25.2 ng/mg, respectively. UCE measurements in both surveys were highly correlated (r = 0.65, P = 0.0001), and 59.6% of the UCE in survey 2 can be explained in linear regression by the UCE in survey 1. Using multiple linear regression, the categorized number of cigarettes reported to be consumed at home (20 cigarettes and more: 1991, P = 0.0001; 1992, P = 0.0003) and low educational level of the parents (P = 0.011 in 1991, P = 0.04 in 1992) were positively associated with UCE, whereas the size of the dwelling turned out to be negatively associated with UCE (P = 0.12 in 1991, P = 0.001 in 1992). In small dwellings (< or = 80 m2) the effect of exposure on UCE was much more pronounced. In conclusion, a single UCE measurement provides information which is widely stable within a yearly interval and is related to passive smoke history as well as to socio-economic status and the size of the dwelling. The latter variable should be considered as an effect modifier of exposure on internal dose and should be taken into account in future studies on passive smoke exposure.

Aromatic hydroxylation in nasal lavage fluid following ambient ozone exposure

Ozone at ambient concentrations affects lung function and initiates an inflammatory response of the airways. However, the underlying mechanisms are poorly understood. In vitro studies have shown that ozone reacts with water to give reactive hydroxyl radicals capable of oxidizing a wide range of biomolecules. We conducted a study to determine if in vivo hydroxyl radical attack on human airways occurs under natural exposure to ozone. The relation of orthotyrosine to para-tyrosine as a measure of hydroxyl radical attack was analyzed in nasal lavage samples of 44 primary school children in an epidemiologic study. Repeated nasal lavages were performed between May and October 1991 both following "low" (daily half-hour maximum < 140 micrograms/m3, approximately 70 ppb) and "high" (daily half-hour maximum > 180 micrograms/m3, approximately 90 ppb) ozone exposure. Concomitantly, lung function tests were performed. On average, 11.6 (6-16) nasal lavages were performed for each of 24 study days (10 days following "low" ozone exposure and 14 days following "high" ozone exposure). Average ortho-tyrosine (median; 5-95% percentile) for each child was 0.037 mumol/L (0.016-0.064 mumol/L) and average para-tyrosine was 15.7 mumol/L (9.8-24.1 mumol/L). Ortho-tyrosine (as percentage of tyrosine) was significantly higher following days with "high" ozone exposure (0.18%) vs. days following "low" ozone exposure (0.02%; p = .0001). Ortho-tyrosine showed an inverse relationship with forced vital capacity (p = .01) but was not related to inflammation of the upper airways as assessed by cell counts of polymorphonuclear neutrophils. Hydroxyl radical attack subsequent to ambient ozone occurs in the upper airways of healthy children and is related to lung function decrements.

Comparison of bronchial challenge with ultrasonic nebulized distilled water and hypertonic saline in children with mild-to-moderate asthma

There is still controversy about the most suitable method to measure bronchial hyperresponsiveness in children. In epidemiological surveys, nonisotonic aerosols are being used increasingly for bronchial provocation testing. Our aim was to study the acceptability, safety and correlation between two published bronchial challenge tests. Two standardized protocols--the inhalation of hypertonic saline (HS) and ultrasonically-nebulized distilled water (UNDW)--were performed in 36 children: 19 patients with the clinical diagnosis of mild-to-moderate asthma (7-12 yrs of age), and 17 control subjects (8-18 yrs of age). HS challenge involved stepwise inhalation of 4.5% saline (for 0.5, 1, 2, 4 and 8 min), whereas challenge with UNDW was performed as a single step protocol with 10 min inhalation of cold UNDW. Asthma medication was withheld prior to challenge testing. Thirty five subjects completed both challenge tests (one asthmatic patient did not return after UNDW challenge) in random order within a 7 day time interval. For HS a > or = 15% reduction in forced expiratory volume in one second (FEV1) from baseline was considered a positive response, and for UNDW a > or = 10% decrease. In 13 of the 19 asthmatic patients, but in none of the controls, a positive response was observed for UNDW. Fifteen out of 18 patients and one control subject had a positive response to HS. Twelve out of 18 asthmatic children responded to both challenges, three responded only to HS and three had no response to either challenge. There was a negative correlation between log provocative dose causing a 15% reduction in FEV1 (PD15) after HS and the maximum fall in FEV1 after UNDW (rs = -0.63; p < 0.005). The HS challenge had a lower acceptability than challenge with UNDW due to the unpleasant salty taste of HS. However, this did not inhibit the completion of the tests in any subject. The results of this study suggest a good correlation between response to hypertonic saline and ultrasonically-nebulized distilled water in children with mild-to-moderate asthma. A multiple step protocol might be safer when applied in field studies involving children.

Therapeutic strategy in a 9-month-old child with pulmonary sling: need for bronchoscopic evaluation

A 9-month-old child presented suffering from repeated severe infections of the lower respiratory tract. Bronchoscopy revealed a tracheal stenosis, suggestive of a vascular anomaly of the great arteries. A second significant stenosis of the left main stem bronchus was observed that was suspected to be due to a ligamentum arteriosum. Heart catheterization confirmed the diagnosis of an abnormal origin of the left pulmonary artery (pulmonary sling). Based on the bronchoscopic and angiographic findings a pulmonary ring was suspected. A dissection of the ligamentum arteriosum was performed. At readmission 4 weeks postoperatively the child was asymptomatic and the left main bronchus was patent.

Mite allergy, clinical atopy, and restriction by HLA class II immune response genes

From a community-based study cohort of 1812 elementary schoolchildren we selected 129 unrelated participants to investigate the relevance of HLA-class II molecules (DPB, DQB, and DRB) to the regulation of immune response to the mite allergen Der p 1 and to clinical atopic disorders. On the basis of skin prick test results validated by measurement of specific IgE, individuals were selected and divided into three groups: group I (n = 20), controls without detectable specific IgE to common inhalant allergens; group II (n = 22), children sensitized only to non-mite allergens; group III (n = 85), children sensitized to Der p 1. Clinical history of asthma, eczema, and hay fever was ascertained using standardized questionnaires. In total, 43 different HLA class II alleles (DPB, n = 19; DQB, n = 14; and DRB, n = 10) were determined by sequence-specific oligonucleotide typing with PCR-amplified DNA. We were not able to demonstrate significant differences in gene frequencies of any HLA class II allele between the group of mite-sensitized children and one of the other two groups. However, the presence of certain DRB- and DPB-haplotypes (DRB *0100/*0300/*1100 and DPB *0201/*0401) was significantly associated (p < or = 0.01) with a history of asthma, hay fever, and atopy (defined as a history of asthma and/or hay fever and/or eczema). Other haplotypes, including DQB *0303/*0503, DRB *0200/ *0700, and DPB 0402 were negatively associated with a history of eczema, hay fever, and atopy (p < or = 0.01). Thus, our findings do not suggest a relevance of HLA-class II molecules to mite allergy; however, some HLA class II haplotypes appear to be predictive of the incidence of atopic disorders.

Sensitization to mite allergens is a risk factor for early and late onset of asthma and for persistence of asthmatic signs in children

BACKGROUND

To describe the natural history of asthma between the ages of 7 and 10 years and to analyze risk factors for prevalences, as well as new onset of asthma-like symptoms, a longitudinal study of 1812 children was conducted.

METHODS

In four surveys, each 1 year apart, four asthma-like symptoms and several hypothetical risk factors were ascertained through standardized questionnaires. Sensitization to seven common inhalant allergens was measured by skin prick testing. Exposure to mite allergens (Der p I, Der f I) was assessed by measuring the antigen concentrations in the dust of each child's mattress. Occurrence of more than one asthma-like symptom closely related to the practioner's diagnoses of bronchial asthma and recurrent wheezy bronchitis was used as the outcome variable.

RESULTS

After an initial prevalence of 14.5%, new onset of symptoms in children unaffected at the beginning was reported in 7.2% during the 3 years. Of the factors explaining prevalence and persistence of asthma-like symptoms (sensitization to mite allergens and animal danders, history of hay fever and eczema, low gestational age, male gender, parental atopy), only sensitization to mite allergens (odds ratio = 2.3, 95% confidence interval = 1.1-4.7) and parental atopy (odds ratio = 2.1, 95% confidence interval = 1.2-3.7) were also significantly associated with new onset. In a relatively small number of sensitized subjects with new onset of symptoms (n = 31), mite antigen concentration did not appear to be associated with incidence of symptoms.

CONCLUSION

Sensitization to mite allergens antedated the onset of asthma-like symptoms, and no strong effect of allergen exposure on clinical development could be found. Thus the primary focus should be on preventing sensitization to mite allergens by implementing avoidance measures in infancy or at early school age in order to reduce the onset of asthma at a later stage.

Acidic particles and lung function in children. A summer camp study in the Austrian Alps

Epidemiological studies have repeatedly demonstrated the effects of acidic particles on lung function. Three consecutive panels of children participating in a summer camp in the Austrian Alps were investigated. On-site pollution assessment consisted of 24-h measurements of particulate matter < 10 microns and the hydrogen, sulfate, and ammonium ion components. The 24-h maximums of ozone and daily pollen counts were also established. For 47, 45, and 41 subjects, daily FEV1, FVC, and peak expiratory flow were recorded. Fifteen percent, 11%, and 5% of participants, respectively, reported current asthma medication, indicating a markedly increased prevalence of respiratory disease. Mean levels of ambient pollutants were approximately 15% higher for the first panel than for the other two panels, but the hydrogen ion (H+) component was twice as high for Panel 1. The maximum H+ exposure during Panel 1 was 84 nmol/m3 (4 micrograms/m3 H2SO4 equivalent). For FEV1 in Panel 1, a significant decrease of -0.99 ml per nmol/m3 H+ (p = 0.01) was observed. For Panel 2, the FEV1/H+ coefficient was found to be similar (-0.74 ml per nmol/m3 H+; p = 0.28), while for Panel 3 it was in the opposite direction (0.10 ml per nmol/m3 H+; p = 0.83). The decrease in FEV1 observed in Panel 1 was more pronounced when the mean exposure during the previous 4 d was considered (-2.99 ml FEV1 per nmol/m3 H+; p = 0.004). We conclude that summer haze acidic particles may be associated with transient decreases in lung function in children.

Variability of peak expiratory flow rate in children: short and long term reproducibility

BACKGROUND

Variability of peak expiratory flow (PEF) has been proposed as a surrogate for bronchial hyperresponsiveness. The normal range of variability of PEF for children has been reported and the test has been used to screen for asthma in population based studies. However, there is little information on the reproducibility of the method in epidemiological settings.

METHODS

In a cohort study of primary school children the variability in PEF was recorded in two consecutive years for one week (first survey) and two weeks (second survey) using mini Wright peak flow meters. PEF was recorded twice daily (morning and evening) and average amplitude as a percentage of mean was calculated as a standard measure of PEF variability for each single week of PEF measurement. Children with PEF variability exceeding the 90% percentile of the distribution for the specific time period were regarded as having increased variability of PEF.

RESULTS

Of 66 children with increased PEF variability in the first year, 13 (19.7%) had an abnormal test in the first week of the second year. Of 543 children with normal PEF variability in the first year, 44 (8.1%) had an abnormal test in the second study year (odds ratio 2.8, confidence interval (CI) 1.4 to 5.4). Of 646 children in the second survey 61 (9.4%) were abnormal during the first week and 68 (10.5%) had an increased PEF variability during the second week, but only 24 (3.7%) children had an increased PEF variability in both weeks. The sensitivity (specificity) for doctor-diagnosed asthma (12 month period prevalence) was 36.4% (91.0%) in the first week of the second survey. When measurements of both weeks of the second survey were used to calculate PEF variability there was little improvement in the sensitivity (38.1%) and specificity (91.5%), mainly because of decreased compliance in the second measurement week.

CONCLUSIONS

In young children assessment of PEF variability in order to screen for asthma is of limited value because of the low reproducibility of the method.

Eosinophils and eosinophil cationic protein in children with and without sensitization to inhalant allergens

Eosinophil inflammation is a common feature of allergic disorders and particularly in allergic asthma interest has been paid to related markers. In a community-based survey of 10-year-old children, the association of eosinophil count (EC) and serum eosinophil cationic protein (ECP) with allergic sensitization, clinical history and exposure to mite allergen was studied. Relying on the results of skin prick tests, the children were divided to three groups: (1) children showing no sensitization to one of the seven inhalant allergens (n = 16); (2) children with sensitization to at least one of five non-mite allergens (n = 16); and (3) children with sensitization to mite allergens (n = 75). Clinical history of asthma and hay fever was ascertained using standardized questionnaires. EC in peripheral blood and serum ECP were measured on one single occasion. Prior to blood sampling, mite allergen exposure at home had been assessed by taking dust samples and measuring the mite antigen concentration by means of an enzyme immunoassay. Compared to group 1, higher ECs were obvious in group 2 (P = 0.037) and in group 3 (P = 0.0013). Regarding serum ECP, higher levels occurred in group 2 (P = 0.0033) as well as in group 3 (P = 0.0001) when comparing them to the reference group. Sensitized children with neither asthma, nor asthma-like symptoms, nor hay fever (n = 28) did not have significantly lower ECs and serum ECP levels than those with hay fever (n = 15; P = 0.09, P = 0.17) and those with asthma (n = 22; P = 0.69, P = 0.64).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessing the effect of time-varying covariates in cross-sectional studies

In cross-sectional studies exposure and disease status of individuals are assessed at the same point in time, but sometimes information on prior exposure status is also gathered. Under such circumstances one approach to assessing the relationship between disease and exposure is using linear or logistic regression analysis, adjusting for exposure status at different points in time. It is shown that estimates for the effect of exposure at a certain point in time, adjusted for exposure at another point in time, are obtained from comparisons between groups with different patterns of exposure. Careful interpretation of the resulting estimates is necessary, taking into account a detailed consideration of possible exposure patterns. In addition, if changes in exposure are caused by the occurrence of the disease, then adjusting for multiple measurements of exposure can give misleading results. A regression analysis on dummy variables describing possible patterns of changes in exposure is proposed as an alternative approach. This approach facilitates interpretation of the resulting estimates. Furthermore, it can serve as a diagnostic tool to check for disease related changes in exposure. For this case transferring exposure change rates of healthy subjects to diseased subjects is suggested as an ad hoc method for assessing the hypothetical current relationship between exposure and disease.

Influence of skin prick test criteria on estimation of prevalence and incidence of allergic sensitization in children

In a prospective cohort study on atopy in childhood, three skin prick tests (SPT) were performed in 1135 primary schoolchildren over a 2-year period. We studied the development of average sizes of allergen wheals in reactive children and of average sizes of histamine wheals in all children, and we investigated the influence of choice of SPT criterion on the prevalence and incidence of sensitization. A year-to-year increase of average allergen wheal sizes as well as of average histamine wheal sizes was observed. These increases seemed to be related to the natural growth of the children. Furthermore, an observer bias effect of the person who did the pricking on average wheal sizes was found. There were considerable differences in estimations of prevalences and incidences depending on the definition of SPT criterion. Estimations using a criterion based solely on the allergen wheal size were affected by variation of allergen wheal sizes caused by growth and observer effects. The ratio criterion was not influenced by observer effects, nor did it seem to be affected by aging effects. In conclusion, our data suggest that the ratio criterion, which relates the size of the allergen wheal to the size of the histamine wheal, is the most appropriate SPT criterion because it is not affected by growth of allergen wheals in childhood and it appears to compensate for possible observer bias.

Mite allergen exposure is a risk for the incidence of specific sensitization

BACKGROUND

Mite allergen exposure is essential for the process of specific allergic sensitization. However, it is not clear whether incidence of specific sensitization at school age depends on the level of mite antigen exposure. Therefore the relationship between mite allergen exposure and incidence of specific sensitization was investigated.

METHODS

Eighteen hundred twelve primary school children were enrolled in a population-based 2-year follow-up study. In three consecutive skin prick tests (SPTs), each 12 months apart, sensitization to Dermatophagoides pteronyssinus (Dpt) and six non-Dpt allergens was ascertained. To assess exposure to Der p I between the first and second SPTs (period I) and the second and third SPTs (period II), the amount of antigen per gram of dust (taken from the children's mattresses was measured. By using the SPT reactions to Dpt as a basis, conversions after "no wheal" were classified as doubtful incidence (average yearly incidence = 6.7%) or definite incidence (average yearly incidence = 3.2%). Then, with the use of multiple logistic regression, the risk of exposure to Der p I (medians: 1.4 micrograms/gm in period I, 1.6 micrograms/gm in period II) was analyzed with adjustment being made for gender, low gestational age, parental atopy, and initial sensitization to non-Dpt allergens.

RESULTS

Regarding doubtful incidence, the analysis failed to identify a reliable cutoff point of exposure. For definite incidence, the Der p I exposure represents a significant risk in the total population, starting from a concentration of 9 micrograms/gm. This effect is modified by an initial sensitization to non-Dpt allergens: for these children exposure to concentrations above 2 micrograms/gm poses a significant risk, whereas for the population without other initial sensitizations, only an extremely high cutoff limit (> 80 micrograms/gm) gains significance.

CONCLUSION

Our data suggest that a concentration limit of 2 micrograms Der p I antigen per gram of dust should be regarded as minimal avoidance level for primary prevention in children with sensitization to other inhalant allergens.

Relationship between atopy and frequent bronchial response to exercise in school children

The natural history of a bronchial response to exercise (BRE) was studied in a cohort of primary-school children, who were followed over a 2-year period. In 1,094 children, three free-running tests were performed in 1-year intervals. Children who responded in one of the tests were designated as "infrequent" responders (20.5%), whereas those responding at two or all three occasions were designated as "frequent" responders (7.4%). A frequent positive BRE was closely associated with atopy (defined as skin test positivity to 1 of 7 common aeroallergens) and respiratory symptom status. Compared to atopics without respiratory symptoms, an increased risk for a frequent positive BRE was seen for atopic children who were symptomatic during the whole study period [odds ratio (OR) 25.4; confidence interval (CI) 6.9-94.0], who had gained symptoms (OR, 11.0; CI, 2.8-43.2) or who had symptoms at the beginning of the study but had lost them during follow-up (OR, 4.6; CI, 1.0-20.6). A sensitization to dust mites (OR, 8.0; CI, 4.3-15.0) but not to animal dander (OR, 2.3; CI, 1.0-5.2) or pollen (OR, 0.7; CI, 0.3-1.6) was significantly related to a frequent positive BRE. Our findings support the notion that while "children grow out of asthma," they might maintain their bronchial hyperresponsiveness. Regarding specific sensitization, mite allergy seems to play the predominant role.

Natural variation in mite antigen density in house dust and relationship to residential factors

To investigate the year-to-year variation of mite antigen density (Der p I, Der fI) in dust from mattresses and the relevance of residential factors for antigen load, information derived from an epidemiologic study including two surveys carried out in the households of a cohort of elementary school children (n = 1291) was analysed. When considering residences with measurements taken in both years in question (n = 1050), rank-correlation indicated a predominance of stability for both antigens (Der p I: rs = 0.82, P = 0.0001; Der f I: rs = 0.72, P = 0.0001). Using multiple regression analyses, significant associations between antigen concentrations and a variety of residential factors were found. Use of a blanket of animal hair, use of a cover or underblanket, wet spots in the bedroom, higher relative humidity and a low storey level were significantly associated with increased concentrations of Der p I, whereas inverse relationships between this antigen and room temperature, number of persons per m2 as well as use of underfloor heating were seen. Regarding Der fI, older mattresses, use of a cover or underblanket, higher weight of sampled dust, high educational level and higher ratio of inhabitants per m2 were significantly associated with increased concentrations of the antigen. On the other hand, lower Der fI concentrations were found when interior sprung mattresses were used and when the mattress was 'treated regularly'. In conclusion, two measurements, 1 year apart from each other, show that stability of mite antigen concentrations predominated.(ABSTRACT TRUNCATED AT 250 WORDS)

Seasonal and allergenic predictors of bronchial responsiveness to distilled water

To evaluate a possible seasonal change in bronchial responsiveness and the relation of such change to atopy, we administered 2,537 bronchial challenge tests in winter and spring to a dynamic population cohort of children 7 to 10 yr of age. The bronchial challenge test consisted of 10 min of tidal inhalation of an aerosol of ultrasonically nebulized distilled water; the resulting percentage decrease in FEV1 (dFEV1%) was recorded. Atopy was determined on the basis of skin-test positivity (any wheal with a diameter greater than that obtained with a positive control) to seven allergens (cat dander, dog dander, house-dust mite, birch, raygrass, orchard grass, and Alternaria). Greater bronchial responsiveness in winter was independently and significantly predicted by a physician's diagnosis of asthma (difference in dFEV1%, 5.6; 95% confidence intervals [95% CI], 2.8 to 8.5; p = 0.0001) and by shortness of breath (difference in dFEV1%, 4.2; 95% CI, 2.1 to 6.3; p = 0.0001). These factors were also predictive of greater responsiveness in the spring, as was atopy (difference in dFEV1%, 3.2; 95% CI, 1.8 to 4.6; p = 0.0001). Analysis of specific allergens further revealed that reactivity to perennial allergens (house-dust mite, cat dander) was predictive of bronchial responsiveness in both winter and spring. However, the change in responsiveness between seasons was most significantly predicted by allergy to seasonal grass pollen, i.e., ragweed or orchard grass (change in dFEV1%, 2.6; 95% CI, 0.6 to 4.5; p = 0.01). In summary, our study demonstrates increased bronchial responsiveness in spring among children allergic to grass pollen.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of maternal smoking on variability of peak expiratory flow rate in school children

Diurnal variability of peak expiratory flow rates (PEFRs) was assessed in 1,237 children. The PEFR was measured twice daily over a 1-week period. As an index of variability, the log of a week's mean of daily amplitude was calculated. Linear regression analyses revealed a significant positive association between maternal smoking and the variability of PEFR for nonasthmatic children. For these children, exposure to maternal smoking was associated with a 13.7 percent increase (confidence interval [CI], 3.8 to 24.7 percent) in PEFR variability. For asthmatic children an effect was found for nonatopic (54.7 percent increase; CI, 5.5 to 226.8 percent) but not for atopic children (-8.5 percent change; CI, -41.2 to 42.3 percent). In the latter group, there was evidence that mothers changed their smoking habits subsequent to the development of disease in their children. We conclude that exposure to maternal smoking can increase the variability of PEFR and thus might contribute to the development of asthma.

Risk factors for childhood asthma and recurrent wheezy bronchitis

Using cross-sectional data of an epidemiological study, risk factors for asthma and recurrent wheezy bronchitis were investigated in 1812 primary school children. Children with asthma (n = 63) had a similar pattern but a higher frequency of chronic respiratory symptoms than those with recurrent wheezy bronchitis (n = 136). Logistic regression analyses showed similar risk factors for both disorders, however, more pronounced for asthma. Prematurity was a significant risk factor for asthma and for recurrent wheezy bronchitis. Children with asthma more often had a family history of paternal or maternal asthma and their mothers tended to be younger. Effects of paternal asthma and prematurity were also found when the atopic status of the child (defined as skin test positivity to any of seven aero allergens) was taken into account. Next to genetic effects, adverse circumstances in early life seem to be important for the development of asthma. In school children recurrent wheezy bronchitis and asthma seem to be similar disorders which differ in quantitative but not qualitative aspects.

The effects of ambient NO2 on lung function in primary schoolchildren

The effect of ambient NO2 on lung function was investigated in a sample of 423 schoolchildren. At each of four locations NO2 was monitored continuously. Over a 6-month period from January to June 1990 two surveys were performed and spirometry recorded each time for each child. Linear regression was used to estimate the effect of NO2 for different time intervals preceding lung function testing. A decrease of NO2 between surveys was significantly associated with a higher forced vital capacity (FVC) at the second survey. For each microgram/m3 NO2 decrease the model predicted an increase in FVC of 1.5 ml [for the 2-hr mean (P < 0.05)] and 3.1 ml [for the 12-hr mean (P < 0.01)]. We conclude that even at NO2 levels below current air-quality standards children demonstrate significant changes in lung function.

Sensitization to four common inhalant allergens within 302 nuclear families

The coincidence of allergic sensitization was investigated in 302 school-aged children and their parents. Specific sensitization to four common inhalant allergens (grass and birch pollens, cat dander, Dermatophagoides pteronyssinus) was ascertained by means of skin-prick tests (SPT) carried out on the complete family unit at the beginning of a 22-month follow-up period. The same test procedure was then repeated on the children twice at 11-month intervals to provide cumulative prevalences of sensitization. A clinical history of atopy in the children (hay fever or asthma; n = 47), which was derived from an interview, is associated with sensitization (positive SPT in 89%). For three allergens (grass and birch pollens, cat dander) sensitization occurs significantly more frequently in the children of mothers who are sensitized to the same allergen (odds-ratios (ORs), 2.5-4.1). Additionally, in three of the four explanatory models related to a single antigen, maternal sensitization to one of the complementary allergens is of importance (ORs, 2.7-3.7). In contrast to this finding, none of the paternal sensitizations has statistical significance. Based on a reaction to at least one of the four allergens, the child's relative risk to be sensitized is increased in case of maternal (OR, 2.88; P = 0.001) but not of paternal (OR, 1.06; P = 0.83) sensitization. In conclusion, our data indicate that the maternal status is more predictive than that of the father with regard to the child's risk of sensitization.

Relation between response to exercise and diurnal variability of peak expiratory flow in primary school children

BACKGROUND

Variability in peak expiratory flow (PEF) has been proposed as a simple method of screening for asthma in epidemiological studies. This study was designed to assess whether the bronchial response to exercise and the diurnal variation in PEF identified the same subjects.

METHODS

Bronchial response to a free running exercise test was assessed in a cohort of 918 seven year old children and was compared with variability of PEF as assessed by twice daily recordings for a one week period. Mini Wright peak flow meters were used throughout the study.

RESULTS

Baseline PEFs of both tests were highly correlated but there was no significant correlation between a response to exercise and variability of PEF. Of 33 children with a physician's diagnosis of asthma, 18 had at least one abnormal test, but only five children were abnormal in both tests, showing that the tests did not identify the same subjects.

CONCLUSION

Increased variability of PEF, as well as a response to exercise, was associated with respiratory symptoms, but only a response to exercise was closely associated with atopy (defined as a positive skin test to any of seven aero-allergens).

[Asthma screening with a standardized running test]

Exercise induced asthma is a common feature of asthma in childhood. We performed a standardized free running test in 1461 primary schoolchildren in first grade (mean age: 7.3 years). A decrease of peak expiratory flow of at least 15% after a 6 minutes exercise period was considered a positive response. For a lifetime prevalence of a physician's diagnosis of asthma the sensitivity of the test was 35.4% and the specificity 94.3%. A positive response was associated with atopy (defined as a positive skin prick test) and with the clinical severity of asthma.

[Variability of peak expiratory flow in an unselected sample of school children]

In the framework of an epidemiological study, the information by peak flow variability (PEFV) was compared to the history of asthma in a non-selected population of primary-school children (n = 1812). PEFV as assessed by twice daily recordings of PEF for a one week period (n = 1237) was calculated as average of daily amplitudes (AVAM: average amplitude mean) in the case of at least complete data for five days (n = 991). Elevated PEFV defined as AVAM > 12%, was cross-tabulated with the asthma history (self-administered questionnaire). The median (90%-confidence-interval) of AVAM is 6.3% (2.2-15.9%). In 11.2% (n = 111) of the population, AVAM > 12% occurred). The sensitivity of AVAM > 12% with regard to "doctor's diagnosed asthma" (n = 35) is 37%. Under exclusion of children with recurrent wheezy bronchitis a specificity for AVAM > 12% of 90% is found. Our data on primary-school children suggests that PEFV is a specific but only slightly sensitive measurement with regard to previously diagnosed bronchial asthma.

[Bronchial hyperreactivity to distilled water]

For an epidemiological study 446 children were challenged with distilled water. The protocol consisted of 10 minutes tidal inhalation of an ultrasonically nebulized aerosol of distilled water. For children presenting with a clinical diagnosis of asthma the odds ratio for a positive challenge test was 9.1 compared to non-asthmatics [95% confidence intervals: 2.4-34.9; p = 0.001]. Symptoms cough (p = 0.03), cough at night (p = 0.03) and atopy defined by prick-test (p = 0.001) were also significantly associated with a positive challenge. The easy conduct of our protocol, the--from a pathophysiological point of view--"close to asthma" stimulus, and the small number of side-effects, indicate that the challenge with distilled water can be regarded as an alternative to metacholine provocation testing.

Clinical atopy and associated factors in primary-school pupils

To investigate potential risk factors for clinical atopy in childhood, we obtained cross-sectional data from a cohort of 1376 8-year-old pupils. Parental atopy (hay fever, asthma, eczema), gestational age, maternal smoking habits, and the child's history of asthma, hay fever, and eczema were ascertained by questionnaire. Combining the history and the result of a skin prick test using seven aeroallergens, we defined the child's atopic diseases. Of the population evaluated, 25.4% were categorized as atopic (10.2% allergic asthma, 17.3% eczema, 6.9% hay fever). As compared with the clear nonatopics (40.2%), parental atopic diseases were more prevalent in each of the atopic groups. Significant associations of the parents' and child's disease were obvious for eczema and hay fever. Low gestational age (LGA) was more frequent in children with any atopy or with an allergic asthma (odds ratio (OR) 1.7; 95% confidence interval (CI) 1.02-2.97; OR 2.8; 95% CI 1.5-5.4). Hay fever and allergic asthma occurred less frequently in girls (OR 0.5; 95% confidence interval 0.3-0.8; OR 0.6; 95% CI 0.4-0.9). In conclusion, our data underline the importance of parental atopy for the clinical outcome in the offspring. In addition, LGA appears to be a risk factor for allergic asthma and for general atopy in later life.

Early childhood risk factors for sensitization at school age

Early childhood risk factors for current sensitization were investigated by use of cross-sectional data of a longitudinal study in Southwest Germany. Information was gathered by questionnaires from 1812 families of whom 1470 children 6 to 8 years old were tested by means of a skin prick test (SPT) with seven aeroallergens. Groups with sensitization (n = 201; positive SPT to grass pollens 6.6%, Dermatophagoides pteronyssinus 6.5%, Dermatophagoides farinae 4.4%, cat dander 4.6%, any of the tested allergens 13.7%) are compared with children without sensitization (n = 1269). As risk factors for any sensitization parental atopy (odds ratio [OR]/95% confidence interval [95%CI]: unilateral 1.9/1.3 to 2.6; bilateral 2.8/1.5 to 5.2), low gestational age (1.9/1.1 to 3.2), and male gender (1.6/1.2 to 2.3) are statistically significant in multiple logistic regression. Former cat ownership is significantly related to sensitization to cat dander (2.7/1.4 to 5.5). Breast feeding, maternal smoking habits after the child's birth, prior exposure to pets, and social class are not important. In conclusion, our data suggest parental atopy, low gestational age, and male gender as independent risk factors for sensitization to aeroallergens at school age.

Longitudinal variability of skin prick test results

The skin prick test (SPT) is a commonly used procedure for assessing a specific sensitization. The longitudinal variability of test results is of interest for clinical as well as epidemiological investigations. The sensitization to four common aeroallergens (grass pollen, birch pollen, Dermatophagoides pteronyssinus, cat dander) is investigated within the framework of three consecutive SPTs at 11-month intervals for a population of 587 schoolchildren. The prevalence of sensitization based on a weal diameter of at least 2 mm was between 12.9% (cat dander) and 23.9% (grass pollen) in the initial testing. The positive predictive values of the initial SPT were between 75.3% (birch pollen) and 88.2% (cat dander) for the two subsequent SPTs. In the case of initially negative tests with positive second and third SPTs the incidence ranged between 3.2% (cat dander) and 4.3% (birch pollen) per year. A clear increase in the intensity of reaction in subsequent tests was observed in a number of probands testing positively in the initial SPT. In conclusion, our data indicate a high long-term stability of a specific sensitization to aeroallergens in SPT.

Determinants of airway response to challenge with distilled water in a population sample of children aged 7 to 10 years old

We challenged 446 schoolchildren and measured the percent decrease in FEV1 following 10 min of tidal inhalation of UNDW. Assessment tools for respiratory symptoms and atopy were questionnaire and skin testing, respectively. A previous diagnosis of asthma was most strongly associated with a positive airway response (defined as a fall in FEV1 greater than or equal to 10 percent. A positive response was also associated with atopy, presence of cough, cough during night, or any respiratory symptom. A child's age and the prechallenge FEF75% also explained response to distilled water indicating less responsiveness for older children and those with relative greater airway diameter. For the previous diagnosis of asthma, a positive distilled water challenge test had a sensitivity of 36 percent and a specificity of 92 percent. We conclude that a significant relationship between airway response to distilled water, asthma and symptoms suggestive for asthma exists for a childhood population sample.

Maternal smoking in early childhood: a risk factor for bronchial responsiveness to exercise in primary-school children

The relationship between maternal smoking and bronchial hyperresponsiveness as assessed by a standardized free running test was investigated in a cohort of 1812 primary-school children in first grade. A child's exposure to maternal smoking during pregnancy, the first year of life, and the study year was recorded. Current exposure was not positively associated with bronchial hyperresponsiveness. The prevalence of this disorder was higher when maternal smoking during the child's first year of life was reported (9%) than when it was not (5.9%). The odds of being hyperresponsive were significantly higher in children exposed to maternal smoking in their first year of life (odds ratio, 2.82; 95% confidence interval, 1.25 to 6.34; p less than 0.01), especially in children with asthma (odds ratio, 20.55; 95% confidence interval, 2.5 to 168.9; p less than 0.01). Current exposure to maternal smoking was associated with less hyperresponsiveness. The effect of current maternal smoking might reflect changes in smoking habits by mothers of children with symptoms, whereas exposure to tobacco smoke in early life might be causally related to bronchial hyperresponsiveness. Our findings support the general hypothesis that early lung injuries have an impact on the later respiratory health of children.

[Respiratory symptoms in children with low birth weight with or without perinatal respiratory insufficiency]

We recorded prevalence of respiratory symptoms in 104 school children aged eight years (+/- 0.4 years) who were born with a weight below 2500 grams. Perinatal respiratory insufficiency (PRI) was observed in 18 children. Validation by medical records in 14 cases demonstrated that 7 children had been oxygen dependent over 1-5 days after birth, the other 7 children had required mechanical ventilation from 2 days up to 4 month. Children with a history of PRI did not suffer more frequently from "cough after exercise" (17%), "wheezing" (50%) or "frequent cough" (11%) than healthy children of low birthweight. Corresponding values were 26%, 38%, and 18% respectively. Multiple logistic regression analyses confirmed these observations. In children with a low birthweight PRI is not associated with respiratory symptoms at school age.

[Effects of traffic-induced emissions on the pediatric respiratory tract]

The aim of this study was to investigate the relationship between paediatric pulmonary function and air pollution. For this purpose, 511 primary schoolchildren (mean age 9 years) from areas with different emission data in Austria were submitted to pulmonary function testing every 2 months in the period 1987/1988. Emission data were provided for NO2, SO2, and O3 by permanent measuring stations for the whole of the period under observation. Statistical analysis using the Mantel-Henzel procedure revealed an independent significantly significant effect of NO2 concentration 2 to 6 hours before the function test on the prevalence of obstructive function.