Chronic Obstructive Pulmonary Disease in Immigrants and Refugees to Ontario, Canada, 2002–2019

<b>Rationale:</b> Canada has welcomed millions of immigrants and refugees in the last decade, and little is known about their chronic obstructive pulmonary disease (COPD) burden. <b>Objectives:</b> To determine the prevalence of COPD among immigrants to Ontario compared with nonimmigrants. <b>Methods:</b> We conducted a population-based cross-sectional study of people aged 35 years 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. <b>Results:</b> Twenty-three percent of Ontario's population aged 35 years and older were immigrants in 2019. 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%, respectively, less likely than nonimmigrants to have COPD. COPD prevalence slightly increased in immigrants over time. In comparison with nonrefugee immigrants, refugee immigrants had a higher prevalence of COPD (adjusted relative risk, 1.33; 95% confidence interval, 1.32-1.33). <b>Conclusions:</b> Immigrants have a lower risk than nonimmigrants of having COPD; however, refugee immigrants had a higher risk than nonrefugee immigrants of COPD. The lower risk in immigrants may be explained by the "healthy immigrant effect," in which immigrants may be generally healthier and younger than locally born individuals. In addition, COPD may be underdiagnosed or underreported in immigrants because of structural barriers to accessing healthcare services. Further research is needed into causes of the difference.