Surveillance of asthma in relation to work among Canada's adult population

Work-related asthma surveillance is needed to improve management of occupational exposures, clinical recognition/diagnosis, and worker compensation policies. This work investigated asthma in relation to work by evaluating the utility of existing Canadian surveillance data in providing useful information about the burden of work-related asthma; estimating the burden of work-related asthma among Canada's adult population; and evaluating the effect of job risk on asthma after considering other potential risk factors for asthma. The working population formed samples from two Statistics Canada surveillance programs: Canadian Community Health Survey (CCHS), 2002/03 Cycle 2.1 and National Population Health Survey (NPHS), Longitudinal Component (1994/95-2002/03). Both surveys enquired about health professional-diagnosed asthma; NPHS additionally asked age at time of diagnosis, so adult-onset versus childhood-onset asthma was determined. Both surveys enquired about current job held; corresponding job codes were linked to an asthma-specific job exposure matrix to judge job risk for occupational asthma. CCHS only provided current job information, in contrast, NPHS longitudinal data was used to determine job held at time of asthma-onset. Statistical measures for asthma in relation to job risk were estimated. CCHS results were likely biased by the healthy worker effect, as it showed the opposite effect of job risk on asthma than the NPHS; higher asthma prevalence was shown for NPHS men and women in high risk jobs. NPHS results indicated a large burden of adult-onset asthma among men (19,000) and childhood-onset asthma among women (17,000) attributed to working in high risk jobs for occupational asthma. Using NPHS, adjusted and crude prevalence odds ratio estimates were compared to further assess effect of job risk on asthma. For adult-onset asthma, there was no difference between estimates (men: 1.8, women: 1.1); for childhood-onset asthma, adjusted estimates were larger than crude, respectively (men: 1.3 v 1.2, women: 2.0 v 1.7). Age of asthma-onset and job held at time of asthma-onset is necessary surveillance information for estimating work-related asthma. There may be increased risk of work" caused" asthma among men and work "exacerbated" asthma among women in high risk jobs. Considering other risk factors for asthma did not reduce effect of job risk on asthma.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat