UBC Theses and Dissertations
Early changes in respiratory health in young apprentices and physician utilization for asthma and bronchitis later in life Peters, Cheryl Elizabeth
Introduction: The main risk factors for the development of respiratory disease have been largely established, however we still cannot predict which individuals will develop respiratory morbidity later in life. This study had two main goals: 1) to examine early working-life changes in respiratory health as risk factors for the development of asthma and bronchitis, and 2) to assess the utility of healthcare utilization data for longitudinal studies in respiratory epidemiology. Methods: A cohort of young apprentices at entry to their trade (machining, construction painting, insulating, and electrician) was enumerated in 1988 to study prospectively the natural history of respiratory morbidity. This group (n=356) was followed-up again two years later. Subjects were linked to a provincial database of all healthcare encounters from 1991 to 2004 (linkage rate 98%). Two health outcomes were studied using physician diagnosis codes: asthma and "bronchitis". Demographics, smoking, spirometric variables, and respiratory symptoms were assessed as predictors of both becoming a respiratory case (logistic regression), and of physician visit rate (negative binomial regression) during the administrative follow-up. Results: There were 281 subjects available for analysis (complete data from baseline, first follow-up, administrative data). Sixteen met the case definition for asthma (2 physician visits in 1 year), and 20 met the case definition for "bronchitis" (3 visits in 1 year). Baseline bronchial responsiveness (BR), and especially a rapid increase in BR over the first 2 years was a strong risk factor for both asthma and "bronchitis". Baseline symptoms of chronic cough or phlegm were predictive of subsequent "bronchitis" visits, and incident asthma-like symptoms were strongly related to subsequent asthma visits. Lung function variables were not important in any models. Relationships were also detected between type of physician, age, sex, job title, size of town, smoking status and the type of respiratory diagnostic code assigned at each physician visit. Conclusions: Early changes in respiratory health may be useful markers in a surveillance program of workers who are susceptible to subsequent obstructive lung disease. Health care utilization data is a unique and promising tool in respiratory epidemiology.
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