Adult Asthma among Workers in Ontario: Results from the Occupational Disease Surveillance System

Logar-Henderson C, MacLeod J, Arrandale V, Holness L, McLeod A, Peter A, Demers P. Annals of the American Thoracic Society Jan 2019 [Epub ahead of print].

Rationale: Given that approximately 15% of new onset adult asthma cases originate due to exposures in the workplace, there is a need for systematic and ongoing monitoring of risk among workers. Objectives: To characterize the risk of new onset adult asthma among workers in Ontario.

Methods: We utilized 575,379 provincial accepted time-loss workers’ compensation claimants data linked to physician billing data. Workers at-risk of new onset adult asthma were followed from cohort entry date to date of diagnosis, emigration, age 65, death, or end of study period. The case definition required 2+ records for asthma within a 12-month period, within a 3-year time window following cohort entry. Cox regression models were used to generate birth year and sex-adjusted hazard ratios (HR) by occupation, industry and exposures identified using a job exposure matrix (JEM). Sex-stratified risk estimates were also generated.

Results: Increased risks were detected among well-recognized groups including bakers (HR 1.60, 95% confidence interval (CI)=1.22-2.09) and painters and decorators (HR 1.67, 95% CI=1.23-2.28). In the JEM analysis, flour and isocyanates were associated with increased risk of asthma. Concrete finishers (HR 1.93, 95% CI=1.12-3.32) and shipping and receiving clerks (HR 1.21, 95% CI=1.03-1.43) also showed elevated risk, while results varied across woodworker groups. Decreased risks were detected for nursing and farming groups.

Conclusions: This practical data linkage approach was successful for examining associations across hundreds of jobs. Unexpected and previously unrecognized findings deserve further investigation and emphasize the importance of an ongoing system to guide research, as well as prevention.