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Asthma prevalence in children varies substantially around the world, but the contribution of known risk factors to this international variation is uncertain. The International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two studied 8-12 year old children in 30 centres worldwide with parent-completed symptom and risk factor questionnaires and aeroallergen skin prick testing. We used multilevel logistic regression modelling to investigate the effect of adjustment for individual and ecological risk factors on the between-centre variation in prevalence of recent wheeze. Adjustment for single individual-level risk factors changed the centre-level variation from a reduction of up to 8.4% (and 8.5% for atopy) to an increase of up to 6.8%. Modelling the 11 most influential environmental factors among all children simultaneously, the centre-level variation changed little overall (2.4% increase). Modelling only factors that decreased the variance, the 6 most influential factors (synthetic and feather quilt, mother's smoking, heating stoves, dampness and foam pillows) in combination resulted in a 21% reduction in variance. Ecological (centre-level) risk factors generally explained higher proportions of the variation than did individual risk factors. Single environmental factors and aeroallergen sensitisation measured at the individual (child) level did not explain much of the between-centre variation in wheeze prevalence.

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Objective Organic waste workers are exposed to high endotoxin levels that may result in respiratory health effects. This study describes changes in lung function and methacholine airway responsiveness over a workweek in household organic waste loaders. Methods Assessment of lung function and methacholine airway responsiveness before and after a workweek in six organic waste loaders with and ten loaders without regular respiratory symptoms. Methacholine responsiveness was expressed as dose-response slope, i. e. % fall in FEV1 per mg methacholine compared to either the postsaline value ( DRSsal), or the highest FEV1 (DRSmax). Results Monday morning, FEV1 was similar in cases and controls. Over the workweek, FEV1 and MMEF decreased slightly in both cases and controls (P > 0.10). In contrast, DRS increased in cases and decreased in control subjects (P

Background: Childhood obesity and asthma are increasing worldwide. A possible link between the two conditions has been postulated. Methods: Cross-sectional studies of stratified random samples of 8-12-year-old children (n=10 652) (16 centres in affluent and 8 centres in non-affluent countries) used the standardized methodology of ISAAC Phase Two. Respiratory and allergic symptoms were ascertained by parental questionnaires. Tests for allergic disease were performed. Height and weight were measured, and overweight and obesity were defined according to international definitions. Prevalence rates and prevalence odds ratios were calculated. Results: Overweight (odds ratio=1.14, 95%-confidence interval: 0.98; 1.33) and obesity (odds ratio=1.67, 95%-confidence interval: 1.25; 2.21) were related to wheeze. The relationship was stronger in affluent than in non-affluent centres. Similar results were found for cough and phlegm, rhinitis and eczema but the associations were mostly driven by children with wheeze. There was a clear association of overweight and obesity with airways obstruction (change in FEV1/FVC, 20.90, 95%-confidence interval: 21.33%; 20.47%, for overweight and 22.46%, 95%-confidence interval: 23.84%; 21.07%, for obesity) whereas the results for the other objective markers, including atopy, were null. Conclusions: Our data from a large international child population confirm that there is a strong relation of body mass index with wheeze especially in affluent countries. Moreover, body mass index is associated with an objective marker of airways obstruction (FEV1/FVC) but no other objective markers of respiratory and allergic disorders. © 2014 Weinmayr et al.

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There is conflicting evidence for the relationship between parental socioeconomic position and their children's asthma. The aim of this study was to investigate relationships between parental education and respiratory symptoms in their children, distinguishing atopic and non-atopic symptoms. A cross-sectional survey among 3262 elementary school children (age 8-13) was performed; data on parental education were obtained for 3213 children. Parents completed a questionnaire on their child's allergic and respiratory symptoms, and potential explanatory variables including family history, indoor environment, and the child's medical history. Subsets of children were tested for atopy (n = 1983), lung function (n = 2325), and airway hyperresponsiveness (AHR) (n = 880). Logistic regression was used to assess relationships of health outcomes with parental education. A high parental education was associated with an increased risk of atopic sensitization to indoor allergens (OR 1.31, 95% CI 1.02; 1.69). Studied explanatory variables did not influence the relationship. In contrast, a high parental education protected children from wheeze (OR 0.77, 95% CI 0.61; 0.97). This only applied to non-atopic wheeze (OR 0.65, 95% CI 0.43; 0.99) and not to atopic wheeze (OR 0.89, 95% CI 0.60; 1.31). The protection from non-atopic wheeze in children of highly educated parents declined after adjustment for household smoking and breastfeeding (OR 0.96, 95% CI 0.58; 1.57). Similar results were observed for non-atopic and atopic rhinitis. We conclude that children from highly educated parents are protected from non-atopic respiratory symptoms, which is largely explained by a lower rate of household smoking and a higher rate of breastfeeding.

The aim of this study was to investigate respiratory effects among emergency services first responders and residents with exposure to combustion products in the aftermath of a chemical waste depot fire.The study population comprised 138 individuals who were present in the area downwind of an accidental fire. Identified by telephone interview six years later, subjects with persistent respiratory symptoms were suspected as having Reactive Airways Dysfunction Syndrome (RADS). Medical tests were performed. For bronchial responsiveness, a cut-off point of PD (20)2.39 mg histamine was taken and a dose-response slope (DRS) was calculated. Suspected RADS cases were compared with healthy controls for exposure to combustion products, lung function, and bronchial responsiveness.The 25 suspected RADS cases were more frequently exposed than the 99 controls; the crude odds ratio for high versus low exposure was 6.5 [95% confidence interval (95% CI) 2.4-18.0]. Suspected cases showed a lower ratio of forced expiratory volume in one second to forced vital capacity (FEV(1)/FVC; P=0.028). Overall, suspected cases had higher DRS than controls. The difference was significant for males only (P=0.006), and non-smoking males (P=0.014). Highly exposed subjects had higher DRS than low exposed subjects (P=0.056). These differences were significant when restricted to non-smokers (P=0.034) and to males (P=0.019). Differences between cases and controls were stronger when the population was restricted to current non-smokers.Persistent respiratory symptoms and bronchial responsiveness were associated with exposure to combustion products of a chemical waste depot fire which occurred more than six years earlier. Authorities and emergency services are recommended to take this into consideration when managing incidents in order to limit possible exposure to airway irritants.

Background For individual exposures, effect modification by atopy or smoking has been reported on the occurrence of occupational airway disease. It is unclear if effect modification can be studied in a general population by an aggregated exposure measure. Assess relationship between airway obstruction and occupational exposure using a job-exposure-matrix (JEM) classifying jobs into 3 broad types of exposure, and test for effect modification by atopy, and smoking. Methods Data from 1,906 subjects were analyzed, all participants of the European Community Respiratory Health Survey. Job titles were categorized by an a priori constructed job exposure matrix into three classes of exposure to respectively organic dust, mineral dust, and gases/ fumes. Relationships were assessed for 'current wheeze', bronchial hyperresponsiveness (BHR), 'current asthma' (wheeze+BHR), and 'chronic bronchitis' (morning phlegm or morning cough), and lung function. Results Subjects with organic dust exposure in their work environment more frequently had 'current asthma' (OR 1.48, 95% C.I. 0.95;2.30), and a lower FEV1 (-59 mL, 95% C.I. -114;-4). The relationship was only present in asthmatic workers, and their risk was four-fold greater than in subjects with either atopy or exposure alone. Mineral dust exposure was associated with 'chronic bronchitis' (OR 2.22, 95% C.I. 1.16;4.23) and a lower FEV1/FVC ratio (-1.1%, 95% C.I. -1.8;-0.3). We observed an excess risk in smokers, greater than the separate effects of smoking or mineral dust exposure together. Conclusion Occupational exposure to organic dust is associated with an increased risk of asthma, particularly in atopics. Chronic bronchitis occurs more frequently among individuals exposed to mineral dust, and smoking doubles this risk.

Background In asthma patients, bronchial hyper‐responsiveness (BHR) to adenosine‐5′‐monophosphate (AMP) reflects bronchial inflammation more closely than BHR to methacholine. In this follow‐up study we studied bronchial responsiveness to both stimuli as predictors of new‐onset airway symptoms. Methods We included 118 laboratory animal workers and bakery apprentices with a work experience of maximally 1 year. The baseline survey comprised a questionnaire, skin prick tests (SPTs) to common and work allergens, blood eosinophil counting, and bronchial challenge with methacholine and AMP. At follow‐up, questionnaire and SPTs to work allergens were repeated. Airway symptoms to common allergens and work allergens were defined as nasal symptoms, chest tightness or asthma attack during or after contact with either common or work allergen. Bronchial challenge tests were analysed by BHR at a 15% fall in forced expiratory volume of 1 s (FEV1), and by dose–response‐slope (DRS). Results Fourteen subjects (12%) developed airway symptoms to work allergens, of whom 12 had nasal symptoms. A positive SPT to work allergens occurred in 64%, and was the strongest predictor of airway symptoms [relative risk (RR) 7.5, 95% confidence interval (CI) 2.0–28.6]. Other predictors were airway symptoms to common allergens (RR 4.3, 95% CI 1.4–12.8), blood hypereosinophilia (RR 4.4, 95% CI 1.2–15.4) and BHR, with a slightly higher risk estimate for AMP than for methacholine (RRAMP 3.7, 95% CI 1.1–12.5 and RRmeth 2.8, 95% CI 1.0–8.5). The difference was more distinct analysing airway responsiveness by DRS, for which AMP predicted symptoms better than methacholine (P

Background Prevalence of exposure related respiratory symptoms and decreases in lung function are unknown among quartz dust exposed construction workers. Methods In a cross-sectional study (n = 1,335), the occurrence of respiratory symptoms, was recorded and spirometric lung function was measured. Results were associated with exposure data and presence of radiographic abnormalities and compared with a reference population. Results Pneumoconiosis (profusion category 1/1 or greater) was associated with increased risks of FEV1 and FVC values in the lowest 5% group, and with group-based decreases of 270 ml/s and 180 ml, respectively. Average lung function of construction workers was somewhat lower compared to a Dutch reference population. Lung function was not associated with exposure, except for a reduction in FVC of 5 ml per year for those with higher exposure. Conclusions In quartz dust exposed construction workers obstructive and restrictive lung function loss was detected. Am. J. Ind. Med. 43:574–583, 2003. © 2003 Wiley-Liss, Inc.

The relationship between exhaled nitric oxide and allergic sensitization in a random sample of school children. van Amsterdam JG, Janssen NA, de Meer G, Fischer PH, Nierkens S, van Loveren H, Opperhuizen A, Steerenberg PA, Brunekreef B. Laboratory of Health Effects Research, National Institute of Public Health and the Environment, Bilthoven, The Netherlands. JGC.van.Amsterdam@rivm.nl BACKGROUND: Exhaled nitric oxide (NO) has been proposed as novel a non-invasive marker of airway inflammation. OBJECTIVE: The level of exhaled NO was determined in a random sample of school children (7-12 years old) with the aim of investigating the relationship between exhaled NO and sensitization to common allergens. RESULTS: In the 450 children tested by skin prick tests (SPT), the prevalence of sensitization was 29.5% (overall), 21.9% (sensitization to indoor allergens), and 15.0% (sensitization to outdoor allergens). Regression analysis showed that levels of exhaled nitric oxide were closely associated with various measures of sensitization to aeroallergens. Sensitization to indoor allergens was associated with higher levels of exhaled NO (eNO) than sensitization to outdoor allergens when assessed by IgE but not when assessed by SPT. Children with reported wheeze in the past 12 months had much stronger associations between sensitization and eNO than children without wheeze. CONCLUSION: We conclude that allergic sensitization is strongly associated with increased levels of exhaled NO, especially in children with wheeze

Bronchial hyperresponsiveness (BHR) and inflammation are central hallmarks of asthma. Studies in patients with asthma suggest that BHR to adenosine 5'-monophosphate (AMP) is a better marker of bronchial inflammation than BHR to methacholine. The association between markers of airway inflammation and BHR to methacholine and AMP in a population of young adults, with mild symptoms if any, was evaluated. A total of 230 subjects who participated in a follow-up study on occupational allergy were included. Before exposure to occupational allergens, subjects completed a questionnaire on respiratory symptoms and were tested for atopy, blood eosinophilia (greater than or equal to 275/mm(3)), and BHR to methacholine and AMP (greater than or equal to 15% fall in FEV1). Risk estimates were expressed as prevalence ratios (PR) and 95% confidence intervals (95% CI). Dose-response slopes (DRS) for methacholine and AMP were compared between healthy control subjects, self-reported allergic rhinitis, and allergic asthma. BHR to AMP was associated with allergic rhinitis (PR 2.51, 95% Cl: 1.22;5.17), allergic asthma (PR 4.38, 95% Cl: 1.98;9.66), with atopy (PR 3.87, 95% Cl: 1.76;8.52), and blood eosinophilia (PR 3.57, 95% Cl: 1.48;8.77), but not with baseline FEV1. BHR to methacholine was inversely related to prechallenge FEV1 (PR 0.97, 95% Cl: 0.96;0.99). For both methacholine and AMP the geometric mean DRS increased along the axis asymptomatic-allergic rhinitis-allergic asthma, but for AMP the increase was the strongest. In this population study among young adults, BHR to AMP refers to allergic background of airway lability and BHR to methacholine is related to a diminished airway caliber.

Bronchial hyperresponsiveness (BHR) and inflammation are central hallmarks of asthma. Studies in patients with asthma suggest that BHR to adenosine 5 ′ -monophosphate (AMP) is a better marker of bronchial inflammation than BHR to methacholine. The association between markers of airway inflammation and BHR to methacholine and AMP in a population of young adults, with mild symptoms if any, was evaluated. A total of 230 subjects who participated in a follow-up study on occupational allergy were included. Before exposure to occupational allergens, subjects completed a questionnaire on respiratory symptoms and were tested for atopy, blood eosinophilia ( ⩾ 275/mm3), and BHR to methacholine and AMP ( ⩾ 15% fall in FEV1). Risk estimates were expressed as prevalence ratios (PR) and 95% confidence intervals (95% CI). Dose– response slopes (DRS) for methacholine and AMP were compared between healthy control subjects, self-reported allergic rhinitis, and allergic asthma. BHR to AMP was associated with allergic rhinitis (PR 2.51, 95% CI: 1.22;5.17), allergic asthma (PR 4.38, 95% CI: 1.98;9.66), with atopy (PR 3.87, 95% CI: 1.76;8.52), and blood eosinophilia (PR 3.57, 95% CI: 1.48;8.77), but not with baseline FEV1. BHR to methacholine was inversely related to prechallenge FEV1 (PR 0.97, 95% CI: 0.96;0.99). For both methacholine and AMP the geometric mean DRS increased along the axis asymptomatic–allergic rhinitis–allergic asthma, but for AMP the increase was the strongest. In this population study among young adults, BHR to AMP refers to allergic background of airway lability and BHR to methacholine is related to a diminished airway caliber.