Chronic obstructive pulmonary disease in immigrants and refugees to Ontario, Canada, 2002-2019

Background — Canada has welcomed millions of immigrants and refugees in the last decade and little is known about their COPD burden. We aim to determine prevalence of COPD among immigrants to Ontario compared to non-immigrants.

Methods — We conducted a population-based cross-sectional study of people age 35 and older living in Ontario between April 1, 2002 and March 30, 2020 using health administrative databases. The primary outcome was COPD prevalence, as ascertained using a validated algorithm. The primary exposure was immigrant status, secondary exposure was refugee status.

Results — Twenty-three percent of Ontario population of 1,738,748 people age 35 and older over the 18 year study period were immigrants. The overall prevalence of COPD was 12%. In adjusted analysis, immigrants < 5 years, 5-14 years, and >15 years from immigration were 76%, 54% and 24% less likely to have COPD than non-immigrants. COPD Prevalence declined in immigrants over time. In comparison to non-refugee immigrants, refugee immigrants had a higher prevalence of COPD (adjusted relative risk 1.33 (95% CI 1.32-1.33).

Discussion — Immigrants have a lower risk of having COPD compared to non-immigrants; however, refugee immigrants had a higher risk of COPD than non-refugee immigrants. The lower risk in immigrants may be explained by the “healthy immigrant effect”, where immigrants may be generally healthier and younger than local-born individuals. Additionally, COPD may be under-diagnosed or under-reported in immigrants due to structural barriers to accessing healthcare services. Further research into causes for the difference is needed.