Geographical variations in the prevalence of atopic sensitization in six study sites across Canada.

Background: Geographical variations in atopic sensitization in Canada have not been described previously. This study used the standardized protocol of the European Community Respiratory Health Survey-1 (ECRHS-1) to investigate the distribution and predictors of atopic sensitization in six sites across Canada and to compare the results with some ECRHS-1 centers.

Methods: Adults aged 20-44 years in six study sites across Canada underwent allergy skin testing using 14 allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae) cat, cockroach, grasses (Timothy grass, Kentucky grass), molds (Cladosporium herbarium, Alternaria alternata, Aspergillus fumigatus, Penicillium), trees (tree mix, birch, Olea europea), and common ragweed.

Work-related asthma in Montreal, Quebec: population attributable risk in a community-based study.

Background: Occupational exposures are an important cause of adult-onset asthma but the population attributable risk percentage (PAR%) has been less frequently studied.

Objectives: To examine the distribution and determinants of adult asthma in six centres across Canada using data gathered in a community-based study.

Methods: Data were gathered in a community survey of 2959 adults using the European Community Respiratory Health Survey Protocol.

Cross-shift peak expiratory flow changes are unassociated with respirable coal dust exposure among South African coal miners.

Background: The objectives of this study were to determine whether cross-shift changes in peak expiratory flow rate (PEFR) were related to respirable dust exposure in South African coalminers.

Methods: Fifty workers were randomly selected from a cohort of 684 miners from 3 bituminous coalmines in Mpumalanga, South Africa. Peak expiratory efforts were measured prior to the commencement of the shift, and at the end of the shift on at least two occasions separated by at least 2 weeks, with full shift personal dust sampling being conducted on each occasion for each participant.

Airflow obstruction in young adults in Canada.

Objective: Airflow obstruction is relatively uncommon in young adults, and may indicate potential for the development of progressive disease. The objective of the present study was to enumerate and characterize airflow obstruction in a random sample of Canadians aged 20 to 44 years.

Setting: The sample (n=2962) was drawn from six Canadian sites.

Asbestos-related diseases of the lungs and pleura: uses, trends and management over the last century.

Asbestos is a descriptive term for a group of naturally occurring minerals known to mankind since ancient times. The main types of asbestos (chrysotile, and the amphiboles crocidolite and amosite) differ in chemical structure, biopersistence in human tissue and toxicity. Commercial exploitation, with little thought for environmental controls, increased over the twentieth century, particularly after World War II, to accommodate globalisation and the demands of the world's burgeoning cities.

Discordance between cross-sectional and longitudinal studies for the effect of dust on COPD: why?

Regression analyses for the effect of an environmental agent on lung function often give discordant results when derived from cross-sectional compared with longitudinal studies. To evaluate why this occurs, a normal population was created by computer, and modeled to simulate functional change during life. Thus, factors known to influence lung function measurement (including those that may cause COPD) were manipulated experimentally so that their contributions to any discordance could be assessed.

Respirable coal dust exposure and respiratory symptoms in South-African coal miners: a comparison of current and ex-miners.

Objectives: Dose-response associations between respirable dust exposure and respiratory symptoms and between symptoms and spirometry outcomes among currently employed and formerly employed South-African coal miners were investigated.

Methods: Work histories, interviews, and spirometry and cumulative exposure were assessed among 684 current and 212 ex-miners.

Results: Lower prevalences of symptoms were found among employed compared with ex-miners.

Childhood predictors of smoking in adolescence: a follow-up study of Montreal schoolchildren.

Background: The factors that cause children to become smokers in adolescence remain unclear. Although parental smoking and peer pressure may play a role, physiological factors such as lung volume have also been identified.

Methods: To investigate these and other possible childhood predictors of teenage smoking, we gathered follow-up data on 191 Montréal schoolchildren, aged 5-12 years (average 9.

Non-malignant consequences of decreasing asbestos exposure in the Brazil chrysotile mines and mills.

Aims: To investigate the consequences of improvement in the workplace environment over six decades (1940-96) in asbestos miners and millers from a developing country (Brazil).

Methods: A total of 3634 Brazilian workers with at least one year of exposure completed a respiratory symptoms questionnaire, chest radiography, and a spirometric evaluation. The study population was separated into three groups whose working conditions improved over time: group I (1940-66, n = 180), group II (1967-76, n = 1317), and group III (1977-96, n = 2137).

Differential respirable dust related lung function effects between current and former South African coal miners.

Dust-related dose-response decrements in lung function among coal miners have been reported in several studies, with varying magnitudes across populations. Few studies have compared differences between current and former coal miners. No studies on dose response relationships with lung function have been conducted in South African coal mines, one of the top three producers of coal internationally.

State of the Art Compendium: Canadian Thoracic Society recommendations for the management of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a common cause of disability and death in Canada. Moreover, morbidity and mortality from COPD continue to rise, and the economic burden is enormous. The main goal of the Canadian Thoracic Society's evidence-based guidelines is to optimize early diagnosis, prevention and management of COPD in Canada.

Geographic and gender variability in the prevalence of bronchial responsiveness in Canada.

Objectives: Geographic variability in reported prevalences of asthma worldwide could in part relate to interpretation of symptoms and diagnostic biases. Bronchial responsiveness measurements provide objective evidence of a common physiologic characteristic of asthma. We measured bronchial responsiveness using the standardized protocol of the European Community Respiratory Health Survey (ECRHS) in six sites in Canada, and compared prevalences across Canada with international sites.

Healthy worker effect in cohort studies on chronic bronchitis.

Objectives: Despite the recognition of selection biases arising from the healthy worker effect in occupational mortality studies, the possibility of similar effects in occupational cohort studies on respiratory symptoms is not well known. Two mechanisms are responsible for the healthy worker effect in respiratory cohort studies. One is health-based selection of workers into employment (healthy him effect), and the other is health-based differential losses to follow-up (healthy worker survivor effect).

Risk factors for bronchial hyperresponsiveness in late childhood and early adolescence.

The prevalence of asthma and bronchial hyperresponsiveness (BHR) tends to decrease in male children but increase in female children in the transition from childhood to adolescence. Hormonal factors may be involved in the natural history of asthma during this period. In a prospective study of Montreal school children, the authors examined the determinants of BHR according to the child's pubertal status; 156 male children and 168 female children without a prior diagnosis of asthma were followed for an average of 4.

Prevalence of vitamin A deficiency in children aged 6-9 years in Wukro, northern Ethiopia.

Objective: To determine the prevalence of vitamin A deficiency in children aged 6-9 years in northern Ethiopia.

Methods: A cross-sectional study was carried out and the data were analysed for 824 (61.5%) of 1339 eligible children for whom there was complete information on biochemical vitamin A status, dietary vitamin A intake, ocular examination for xerophthalmia, and anthropometry.

Association between vitamin A status and lung function level in children aged 6--9 years in Wukro wereda, Northern Ethiopia.

Background: In developing countries, studies using morbidity recalls to evaluate the benefits of vitamin A on respiratory health in children under 6 years of age have been inconclusive. This relationship has not been examined in older children. Spirometric measurements, an objective means of assessing respiratory health, require the subject's collaboration and have been successfully used in children over 6 years of age.

Prevalence of asthma symptoms among adults aged 20-44 years in Canada.

Background: Reported prevalence rates of asthma vary within and between countries around the world. These differences suggest environmental factors in addition to genetic factors in the cause of the disease and may provide clues for preventive strategies. We examined the variability of asthma-related symptoms and medication use among adults in 6 sites across Canada (Vancouver, Winnipeg, Hamilton, Montreal, Halifax and Prince Edward Island) and compared our findings with those from sites that had participated in a recent European survey.