Joan Raven

Biological dust exposure in the workplace is a risk factor for chronic obstructive pulmonary disease

Background: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Although the main risk factor is smoking, 15–19% of COPD even in smokers has been attributed to occupational exposures. The aim of this study was to investigate the association between occupational exposure and risk of COPD. Methods: Participants were part of a cross sectional study of risk factors for COPD. A total of 1232 completed a detailed respiratory questionnaire, spirometric testsing and measurement of gas transfer. Job histories were coded according to the International Standard Classification of Occupations. These codes were then used to establish occupational exposures using the ALOHA job exposure matrix. Results: The prevalence of emphysema was 2.4%, chronic obstructive bronchitis 1.8%, and COPD 3.4%. Subjects ever exposed to biological dusts had an increased risk of chronic obstructive bronchitis (OR 3.19; 95% CI 1.27 to 7.97), emphysema (OR 3.18; 95% CI 1.41 to 7.13), and COPD (OR 2.70, 95% CI 1.39 to 5.23). These risks were higher in women than in men. For biological dust, the risk of emphysema and COPD was also significantly increased in both the duration of exposure categories, again in women but not in men. No significant increased risks for COPD were found for mineral dust (OR 1.13; 95% CI 0.57 to 2.27) or gases/fumes (OR 1.63; 95% CI 0.83 to 3.22). Conclusion: In this general population sample of adults, occupational exposures to biological dusts were associated with an increased risk of COPD which was higher in women. Preventive strategies should be aimed at reducing exposure to these agents in the workplace.

Linkage of high-affinity IgE receptor gene with bronchial hyperreactivity, even in absence of atopy

Asthma is a manifestation of bronchial hyperreactivity (BHR) and forms part of the spectrum of atopic disease. Some pedigree studies of atopy have suggested linkage with the high-affinity IgE receptor (Fc epsilon RI beta) gene on chromosome 11q13, but others find no linkage. The molecular genetics of asthma and BHR have not been studied in the general population. We examined the genetic linkage of the Fc epsilon RI beta gene with clinical asthma and the underlying phenotypes of BHR (to methacholine) and atopy (defined by skinprick testing) in 123 affected sibling-pairs recruited from the general population. We found evidence of significant linkage of a highly polymorphic microsatellite marker in the fifth intron of the Fc epsilon RI beta gene to a diagnosis of asthma (18.0% excess of shared alleles, p = 0.002) and to BHR (21.7% excess of shared alleles, p = 0.001). Significant linkage was also observed in siblings sharing BHR when those with atopy were excluded (32.8% excess of shared alleles, p = 0.004). Atopy in the absence of BHR did not show significant linkage to the Fc epsilon RI beta gene (7.2% excess of shared alleles, p = 0.124). These findings suggest that mutations in the Fc epsilon RI beta gene or a closely linked gene influence the BHR underlying asthma, even in the absence of atopy.

Reported adverse food reactions overestimate true food allergy in the community

Objective: To determine the extent to which perceived adverse food reactions were associated with IgE mediated food allergy, as defined by skin prick testing (SPT).Design: A cohort epidemiological study. Participants underwent SPT to five common food allergens (cows milk, peanut mix, egg white, shrimp and whole grain wheat mix) and were asked whether they had ever suffered any food ‘illness/trouble’, and if so to list such food(s). A positive SPT was defined as wheal diameter of ≥3 mm. Cohens kappa (κ) was used to assess the agreement between SPT and self-reported reactions to food(s) which contained the allergen of interest.Setting: Randomly selected adults who took part in the follow-up of the European Community Respiratory Health Survey (ECRHS) in 1998.Subjects: The subjects were 457 adults aged 26–50 y.Results: Fifty-eight (13%) adults were sensitised to at least one food allergen whilst 99 adults (22%) reported illness to food(s) nearly always. However, only seven subjects who reported illness to a food also had a positive SPT to the same food. The prevalence of adverse food reactions associated with IgE mediated allergy in the adult general population would be less than 1.5% (7/457). The agreement between SPT and self-reported illness to food(s) was poor for cows milk (κ=0) and wheat (κ=0), slight for shrimp (κ=0.16) and egg white (κ=0.09) and fair for peanut mix (κ=0.37).Conclusions: There was little agreement between self-reported perceived illness to food(s) known to contain the food allergen of interest, and positive SPT, suggesting that most reactions are not due to IgE mediated food allergy.Sponsorship: The National Health and Medical Research Council of Australia (NH&MRC) funded this study. Rosalie Woods holds a postdoctoral research fellowship from the NH&MRC (#9797/0883).

Prevalence of food allergies in young adults and their relationship to asthma, nasal allergies, and eczema

BACKGROUND The true prevalence of food allergy in adults is generally thought to be uncommon. It is unknown whether there are any relationships between food allergy and atopic diseases. OBJECTIVE To determine the prevalence of probable immunoglobulin (Ig)E-mediated food allergy to peanut, shrimp, cows milk, wheat, and egg as defined by a positive skin prick test result and relevant clinical history to the same food, and to explore the relationship with atopic diseases. METHODS Cross-sectional epidemiologic study. One thousand one hundred forty-one randomly selected young adults (aged 20 to 45 years) underwent skin prick testing to five common food allergens (cows milk, peanut, egg white, shrimp, and wheat), completed a detailed questionnaire, including validated items on respiratory symptoms, history of asthma and other allergic conditions, as well as undergoing lung function testing. RESULTS Just over one percent (1.3%, n = 15) had probable IgE-mediated food allergy. The prevalence of probable IgE food allergy was: <0.27% for wheat, 0.09% (95% confidence interval = 0.0 to 0.49%) each for cows milk and egg, 0.53% (0.21 to 1.09%) for shrimp, and 0.61% (0.25 to 1.26%) for peanut. Those with probable IgE peanut and shrimp allergy were significantly more likely to have current asthma and doctor-diagnosed asthma. Wheeze and history of eczema were also associated with peanut allergy, whereas nasal allergies were associated with shrimp allergy. CONCLUSIONS The prevalence of probable IgE-mediated food reactions is rare in young adults. Some positive associations between probable IgE-mediated food allergy and allergic diseases were found, but larger study numbers are required to confirm these results.

Prevalence and residential determinants of fungi within homes in Melbourne, Australia

Recent epidemiological studies suggest that the adverse respiratory health effects caused by the inhalation of fungal propagules are substantial. Knowledge of the prevalence and environmental determinants of indoor fungal levels is essential in designing effective avoidance measures.

Mouldy houses influence symptoms of asthma among atopic individuals

Background The influence of current levels of indoor fungi on asthma is a controversial issue that needs to be resolved in order to advise patients appropriately.

Changes in indoor allergen and fungal levels predict changes in asthma activity among young adults

Background Exposures to allergens are thought to be important risk factors for asthma. We conducted a longitudinal study of indoor allergen and fungal levels in Melbourne homes between 1996 and 1998 to examine the effect of changes in allergen exposure upon asthma and associated outcomes.

Fatty acid levels and risk of asthma in young adults

Background: There is current interest in the possible protective effect of long chain (n-3) fatty acids from fish in chronic lung diseases such as asthma. The aim of this community based cross sectional study was to determine whether plasma long chain (n-3) fatty acids, as a measure of dietary intake, differed between 1601 young adults with and without asthma. Methods: Subjects of mean (SD) age 34.6 (7.1) years completed a detailed respiratory questionnaire, food frequency questionnaire, skin prick testing, and lung function tests including methacholine challenge test for bronchial hyperreactivity (BHR) and had venous blood taken for analysis of plasma fatty acids. Plasma fatty acid levels (%) were analysed using multiple logistic regression with alternative definitions of asthma and atopy as the outcomes. Results: Atopy was not associated with any plasma fatty acid. The n-3 polyunsaturated fatty acids and n-6:n-3 ratio were not consistently associated with asthma or atopy. The n-6 polyunsaturated fatty acid dihomo γ-linolenic acid (DHGLA) was positively associated with current asthma (OR = 1.30, 95% CI 1.06 to 1.60), asthma (OR = 1.34, 95% CI 1.13 to 1.60), and doctor diagnosed asthma (OR = 1.25, 95% CI 1.06 to 1.48). Conclusion: Plasma n-3 fatty acids are not associated with a reduced risk of asthma or atopy among young adults. The association of DHGLA with asthma warrants further research to determine a cause-effect relationship.

Risk factors for asthma among young adults in Melbourne, Australia

Abstract Asthma is more prevalent in Australia than in Europe or North America. As part of the European Community Respiratory Health Survey (ECRHS), we investigated exposure to risk factors for asthma among young adults in Melbourne. During this study, 553 randomly selected and 204 symptomatic participants aged between 20 and 44 years completed a detailed respiratory questionnaire, of whom 675 underwent measurement of bronchial hyperreactivity (BHR) by methacholine challenge and 745 had skin prick tests for atopy. Current asthma, defined as BHR and wheeze in the preceding 12 months, was present in 25.5% of those tested. A family history of asthma was a risk factor for current asthma (maternal asthma odds ratio [OR] 2.4, paternal asthma OR 2.1). Current smokers were 1.7 times more likely to have current asthma. A serious respiratory infection before 5 years of age increased the risk of current asthma 2.3‐fold. Atopy on skin testing was also strongly associated with current asthma (OR 5.9). The greatest risks were associated with positive skin tests to Cladosporium, house dust mite, cat and rye grass pollen. We conclude that female gender, maternal asthma, smoking, hayfever, early respiratory infection, occupational exposure and atopy are important risk factors for asthma in young adults.

β2-adrenergic receptor polymorphisms are associated with asthma and COPD in adults

AbstractThe β2-adrenergic receptor (β2AR) is a transmembrane protein expressed by airway smooth muscle cells. In vitro studies have shown that polymorphisms at amino acid positions 16 and 27 alter receptor function. The aim of this study was to examine the associations between the β2AR polymorphisms and risks of asthma, chronic obstructive pulmonary disease (COPD) and respiratory symptoms in a sample of adults. Participants were part of a cross-sectional population-based study of risk factors for respiratory disease. A total of 1,090 Caucasian participants completed a detailed respiratory questionnaire, spirometry, methacholine challenge and measurement of gas transfer. Genotyping for β2AR polymorphisms at positions 16 and 27 was performed using the tetra-primer amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) method. Haplotype frequencies for the two polymorphisms were estimated using the E-M algorithm. We found the Arg16 homozygotes had an increased risk of COPD (OR 5.13; 95% CI 1.40,18.8), asthma (2.44; 1.12,5.31) and symptoms of wheeze (1.84; 1.02,3.35). The Gln27 homozygotes had an increased risk of asthma (2.08; 1.05,4.13) and bronchial hyperreactivity (BHR) (1.92; 1.07,3.46). The Arg16/Gln27 haplotype was associated with asthma (1.63; 1.12,2.38) and COPD (2.91; 1.42,5.94). The Arg16/Gln27 β2AR haplotype is important in COPD, asthma and BHR, and may be associated with more severe respiratory symptoms in middle-aged and older adults.