An international prospective general population-based study of respiratory work disability.

BACKGROUND: Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability. METHODS: A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems. RESULTS: The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9). CONCLUSIONS: Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures.

Association between modelled traffic-related air pollution and asthma score in the ECRHS.

The aim of our analysis was to study the association between air pollution and asthma among adults. For this goal, a previously developed "asthma score" was used. Persons aged 25-44 yrs were randomly selected (1991-1993) and followed up (2000-2002) within the European Community Respiratory Health Survey (ECRHS I and II, respectively). The asthma score was defined from 0 to 5, based on the positive answers to the following symptoms reported for the last 12 months: wheeze/breathlessness, chest tightness, dyspnoea at rest, dyspnoea after exercise and woken by dyspnoea. Participants' home addresses were linked to outdoor modelled NO2 estimates for 2001. Negative binomial regression was used to model the asthma score. The score from ECRHS II was positively associated with NO2 (ratio of the mean asthma score (RMS) 1.23, 95% CI 1.09-1.38, for an increase of 10 microg x m(-3)). After excluding participants with asthma and symptoms at baseline, the association remained (RMS 1.25, 95% CI 1.05-1.51), and was particularly high among those reporting a high score in ECRHS II. The latter probably reflects incident cases of asthma. Our results suggest that traffic-related pollution causes asthma symptoms and possibly asthma incidence in adults. The asthma score offers an alternative with which to investigate the course and aetiology of asthma in adults.

Sensitization to individual allergens as risk factors for lower FEV1 in young adults. European Community Respiratory Health Survey.

BACKGROUND: Atopy may impair ventilatory function, but results are controversial. We assess the association between individual reactivity to allergens and the level of baseline maximal one-second forced expiratory volume (FEV1), by smoking and respiratory symptoms. METHODS: The 1472 participants (response 44.5%) of the five Spanish areas of the European Community Respiratory Health Survey (ECRHS) who performed respiratory function tests, skin prick tests and/or specific IgE against common aeroallergens (e.g. mites, pets, mould, pollens) are included. Bronchial hyperreactivity (BHR) was measured with a methacholine challenge. RESULTS: After adjusting for BHR and smoking, in addition to the other allergens, skin reactivity to Alternaria (-208 ml; 95% CI :-451, 35) and IgE antibodies against cat (-124 ml; 95% CI:-269, 21) and Timothy grass (-115 ml, 95% CI:-190, -40) were associated with a decrease in FEV1 in females. Among males, skin reactivity to olive showed the strongest association (-111 ml; 95% CI: -261, 38). The associations were stronger in females. Smoking modifies the association for Alternaria and cat (P for interaction < 0.05). While cat is associated with a decrease in FEV1 in current smokers (-190 ml), Alternaria (-336 ml) was associated among never smokers. The exclusion of subjects with asthma symptoms, or adjustment for respiratory symptoms, led to similar results. CONCLUSIONS: We conclude that immunoresponse to individual allergens (particularly outdoor) is associated with the level of FEV1, and this association occurred independently of asthma, and in smokers and non-smokers, which may be of interest in natural history of chronic obstructive pulmonary disease (COPD).

Asthma risk, cleaning activities and use of specific cleaning products among Spanish indoor cleaners.

OBJECTIVES: Recent studies have shown an excess risk of asthma for cleaners, but it is not clear which cleaning-related exposures induce or aggravate asthma. METHODS: Risk factors for asthma were studied among indoor cleaners participating in the Spanish part of the European Community Respiratory Health Survey in 1992. In 1998, 78 of the 91 subjects reporting cleaning-related jobs in 1992 were identified. Of these, 67 indoor cleaners were interviewed by telephone about their cleaning activities and their use of cleaning products in 1992. These data were related to asthma prevalence in 1992, and the cleaners were compared with a reference group of office workers. RESULTS: Asthma prevalence was 1.7 times higher [95% confidence interval (95% CI) 1.1-2.6] among the cleaners than among the referents, being highest among private home cleaners (3.3, 95% CI 1.9-5.8). The prevalence of housedust mite sensitization amounted to 28% for the home cleaners and was significantly (P<0.01) higher than for other indoor cleaners (3%), but similar to the corresponding prevalence of office workers (22%). More than half of the cleaners reported work-related respiratory symptoms. The asthma risk of the home cleaners was mainly associated with kitchen cleaning and furniture polishing, with the use of oven sprays and polishes. CONCLUSIONS: The asthma risk of Spanish cleaners is primarily related to the cleaning of private homes. This relationship may be explained by the use of sprays and other products in kitchen cleaning and furniture polishing.

[European Asthma Study. Identifying and treating young adults with epidemiological criteria for asthma in five areas of Spain. Spanish Group of the European Asthma Study]. / Estudio Europeo del Asma. Identificación y tratamiento de individuos con criterios epidemiólogicos de asma en adultos jóvenes de cinco áreas españolas. Grupo Español del Estudio Europeo del Asma.

BACKGROUND AND OBJECTIVES: Asthma's great impact on public health stems from its chronicity and to high prevalence among all age groups and both sexes. To estimate the appropriateness of treatment and management of asthma in Spain during the period of 1991 and 1992, we analyzed data from the European Community Respiratory Health Survey (ECRHS). METHOD: The ECRHS was undertaken with a random sample of 20-to-44-year-olds in Albacete, Barcelona, Galdakao, Huelva and Oviedo. In total, 181 individuals with asthma were identified. Current asthma was defined as the presence of respiratory symptoms associated with asthma within the past 12 months and a positive methacholine challenge test. RESULTS: Subjects who were unaware of having asthma made up 57.5% (CI: 49.9-64.8%), and 35.9% (CI: 27.9-42.3%) were not following any specific treatment. Among asthmatics who reported having continuous or frequent respiratory symptoms, 25.9% (CI: 15.3-39.0%) were not following any treatment. CONCLUSION: Over half the individuals with asthma in 1991 to 1993 were unaware of having the disease at the time of the study or of ever having had it, and approximately one third were not in treatment. The delivery of appropriate treatment in asthma generally, and in asthma with continuous or frequent respiratory symptoms, was markedly inadequate during the period studied.

[Association between the forced midexpiratory flow/forced vital capacity ratio and bronchial hyperresponsiveness]. / Asociación entre el cociente FEF(25-75%)/FVC y la hiperreactividad bronquial.

OBJECTIVE: A long-standing hypothesis is that a low ratio of airway caliber to lung size is associated with bronchial hyperresponsiveness (BHR). The aim of our study was to measure the association between airway caliber relative to lung size (expressed as the ratio between forced expiratory flow, midexpiratory phase, divided by forced vital capacity [FEF(25%-75%)/FVC]) and BHR measured by a methacholine challenge test, adjusting for age, height, sex, smoking history, geographic area, respiratory symptoms, and baseline forced expiratory volume in 1 second (FEV1). MATERIAL AND METHODS: We carried out a multicenter cross-sectional study of the general Spanish population in 2647 subjects from the European Community Respiratory Health Survey (ECRHS I). The ECRHS questionnaire was administered, total and specific immunoglobulin E were measured, and skin tests, spirometry, and a methacholine challenge test were performed. RESULTS: We show the relationship of the various clinical and sociodemographic variables with the 2 parameters indicative of a positive methacholine test. The lower the FEF(25%-75%)/FVC ratio was, the greater the risk of HRB, after adjustment for variables (odds ratio [OR]=0.09; 95% confidence interval [CI], 0.04-0.018 for the concentration provoking a 20% decrease in FEV1, and OR=0.06; 95% CI, 0.03-0.12 for the dose provoking a 20% decrease in FEV1). CONCLUSIONS: There is a significant association between the FEF(25%-75%)/FVC ratio and BHR after adjustment for age, atopy, smoking, geographic area, respiratory symptoms, and initial FEV1.

Lung function and airway responsiveness in children and adolescents after hyaline membrane disease: a matched cohort study.

Some investigators consider prematurity to be responsible for the lung function abnormalities found in prematurely born children and adolescents who had neonatal respiratory diseases. This study attempts to measure the effect of neonatal respiratory disease on lung function during school age and adolescence, by controlling the confounding effect due to prematurity. Lung volumes, airway resistance and specific airway conductance measured by plethysmography, maximum expiratory flow-volume curves, pulmonary diffusion of carbon monoxide, and the airway responsiveness to a challenge with methacholine, were determined in a cohort of children aged 8-14 yrs, who had suffered from hyaline membrane disease but who did not develop bronchopulmonary dysplasia. The values obtained were compared with those of children without hyaline membrane disease, not ventilated for other causes, and matched for gestational age, sex and age. Thirty six pairs of children were enrolled, of which 26 participated in the methacholine test. Compared to their paired controls, children with hyaline membrane disease had a significantly lower forced expiratory volume in one second (FEV1), forced mid-expiratory flow (FEF25-75), and maximal expiratory flow when 75, 50 and 25% of the forced vital capacity remained in the lung (MEF75, MEF50 and MEF25, respectively), and a significantly higher airway resistance (Raw). The effect was less in children born more prematurely, who showed less difference in FEF25-75, MEF75 and MEF25. The duration of treatment with steroids in the neonatal period was associated with a reduction in the differences in FEV1, MEF25 and Raw. Independent of prematurity, hyaline membrane disease and its treatment is associated with alterations in long-term lung function, even in children who do not develop bronchopulmonary dysplasia. The effect can be less in more premature children, and neonatal steroids can have a long-term preventive effect.

Incidence of asthma and its determinants among adults in Spain.

The objective was to measure the incidence of asthma and its determinants in Spain, where the prevalence of asthma is low to medium. A follow-up of subjects participating in the European Community Respiratory Health Survey (ECRHS) was conducted in 1998- 1999 (n = 1,640, 85% of those eligible). Subjects were randomly selected from the general population and were 20 to 44 yr old in 1991-1993. Time of follow-up was on average 6.75 yr (range, 5.3 to 7.9 yr). Asthma was defined as reporting ever having had asthma. The incidence of asthma was 5.53 (95% confidence interval, 4.28- 7.16) per 1,000 person-years (6.88 in females, 4.04 in males). Incidence was highest in subjects who at the baseline survey had bronchial hyperresponsiveness (incidence rate ratio [IRR], 3.85), in those with positive IgE against timothy grass (IRR, 3.16), and in females (IRR, 1.80). These results persisted after adjusting for respiratory symptoms at baseline. There was no significant association (p < 0.2) with high total serum IgE, atopy defined by reactivity to any allergen, smoking, occupational exposure, or maternal asthma. A sensitivity analysis using four definitions of population at risk yielded incidence rates varying from 5.53 to 1.50. In this population of subjects without self-reported asthma or asthma-type symptoms at baseline, bronchial hyperresponsiveness and IgE reactivity to grass appeared as the main determinants of new asthma.

Atopy and nonspecific bronchial responsiveness. A population-based assessment. Spanish Group of the European Community Respiratory Health Survey.

The relative importance of specific immunoresponse in explaining nonspecific bronchial responsiveness (BR) has scarcely been examined. We provide quantitative estimates of the proportion of BR attributable to specific atopy to different common aeroallergens. We used data from a cross-sectional study on a random sample of the general population 20 to 44 yr of age from five Spanish areas. There were 1,816 participants who performed a methacholine challenge and had atopy assessed. BR was defined as a 20% or more fall in FEV1. Atopy was assessed by measuring serum-specific IgE or skin tests to cat, Dermatophagoides pteronyssinus, Cladosporium, Alternaria, timothy grass, olive, birch, Parietaria, or ragweed. The strongest associations between BR and specific IgE response were against timothy grass (prevalence rate ratio = 1.78; 95% confidence interval 1.2 to 2.6), Dermatophagoides pteronyssinus = 1.64 (1.2 to 2.2), and olive = 2.36 (1.5 to 3.7), all after adjustment by age, sex, area of residence, smoking, and a positive response to any of the other eight allergens measured. The population attributable risk of BR for a positive response to any of the nine allergens measured was 20.96% (10.2 to 43.2%) when adjusting for area of residence, age, sex, and smoking. Nonspecific bronchial responsiveness in the general population was found to be related to atopy against single specific allergens, but the population risk attributable to atopy may be lower than previously suggested.

Risk factors for asthma in young adults. Spanish Group of the European Community Respiratory Health Survey.

We assessed the association of asthma prevalence in young adults with susceptibility factors and environmental exposures, taking into account the age at asthma onset. A random sample of the general population, aged 20-44 yrs, in five areas of Spain (Albacete, Barcelona, Galdakao, Huelva, and Oviedo) was selected in the frame of the European Community Respiratory Health Survey (ECRHS). Overall, 2,646 subjects (response rate = 60.9%) responded to a respiratory questionnaire and 1,797 (41.4%) finalized a bronchial challenge. Atopy to perennial (odds ratio (OR) = 10.2, 95% confidence interval 4.2-25) and seasonal allergens (11.5, 4.6-28), parental asthma (4.5, 2.5-8.4), and birth order (OR for no older siblings in comparison to having more than two = 3.2, 1.2-9.1) were associated with current asthma whatever the age of asthma onset. Past asthma was associated to a lesser extent with atopy (OR around 3.5 to both perennial and seasonal allergens). Lower respiratory tract infections before the age of 5 yrs (LRTI), having had a pet in childhood, and being born in a younger cohort were associated with asthma starting before the age of 15 yrs, but not after. Male gender was more frequent in childhood asthma and female gender in adulthood. In addition to the known risk factors of asthma (atopy to perennial allergens, parental asthma) we provide evidence for an association of asthma (whatever the age of onset) with sensitization to seasonal allergens, and having less than three older siblings; and for an association of childhood asthma with lower respiratory tract infections.

Pulmonary ventilatory defects and occupational exposures in a population-based study in Spain. Spanish Group of the European Community Respiratory Health Survey.

We assessed the association between occupational exposures and symptoms of chronic bronchitis and pulmonary ventilatory defects in a general population-based study of five areas in Spain. This study forms part of the European Community Respiratory Health Study (ECRHS). Subjects (n = 1,735; age range, 20-44 yr; 52.4% of those initially selected) completed a respiratory questionnaire on symptoms and occupation and underwent baseline spirometry. Occupation was translated with an ad hoc developed job-exposure matrix (EM) into none, low, and high exposure to biological dust, mineral dust, and gases and fumes. Exposure to high levels of biological dust was associated with cough for more than 3 mo (odds ratio [OR], 1.9; p = 0.07), a reduction in FEF(25-27) to 478 ml/s (SD 178), and a reduction in FEV1 to 151 mL (SD 71). These associations remained after excluding subjects with asthma symptoms or bronchial responsiveness. Smokers tended to have a higher risk for respiratory symptoms, but smoking did not modify the association of occupation with pulmonary function. Exposure to mineral dust and gases/fumes was less consistently related to pulmonary function or to respiratory symptoms and this association further decreased after excluding subjects with asthma. In conclusion, exposure to high levels of biological dust in young adults is associated with symptoms of chronic bronchitis and pulmonary ventilatory defects, independently of asthma and smoking.

Respiratory symptoms, lung function and use of health services among unemployed young adults in Spain. Spanish Group of the European Community Respiratory Health Survey.

The association of respiratory symptoms, lung function and use of health services with employment status was examined in Spain, a country with a high rate of unemployment. A population sample comprising 179 unemployed and 1,868 employed subjects aged 20-44 yrs in 1993, was randomly selected from a base population of about 170,000 people in five urban and rural areas of Spain. Subjects completed a questionnaire on respiratory symptoms, sociodemographic and lifestyle factors, occupational exposure and use of health services, and performed a forced spirometry, a methacholine challenge test and blood tests. Unemployed subjects had a higher risk of simple chronic bronchitis (odds ratio=2.06, 95% confidence interval 1.30-3.24) and of bronchitis-type symptoms, than those who were employed. These risks were, in part, due to the higher prevalence of smoking, poorer housing and prior occupational exposures among unemployed than among employed people. Smaller differences were found between employed and unemployed subjects for asthma-type symptoms, atopia and lung function tests. Use of health services among subjects with respiratory symptoms was similar among employed and unemployed subjects, except that the latter consistently reported less frequent contact with specialized practitioners. Unemployed subjects had a higher risk of bronchitis-type symptoms than employed subjects. In Spain's national, free-access healthcare system, the differential use of specialized health services by employment status is likely to imply differences in the characteristics of the healthcare provided.