Immigration Status, Ethnicity, and Long-term Outcomes Following Ischemic Stroke
Manav V. Vyas, Peter C. Austin, Jiming Fang, Andreas Laupacis, Frank L. Silver, Moira K. Kapral
Abstract
<h3>Objective</h3> To assess the association between immigration status and ethnicity and the outcomes of mortality and vascular event recurrence following ischemic stroke in Ontario, Canada. <h3>Methods</h3> We conducted a retrospective cohort study using linked administrative and clinical registry–based data from 2002 to 2018 and compared hazards of all-cause mortality and vascular event recurrence in immigrants and long-term residents using inverse probability of treatment weighting accounting for age, sex, income, and comorbidities. We stratified analyses by age (≤75 and >75 years) and used interaction terms to evaluate whether the association between immigration status and outcomes varied with age or ethnicity. <h3>Results</h3> We followed 31,918 adult patients, of whom 2,740 (8.6%) were immigrants, for a median follow-up of 5 years. Immigrants had lower mortality than long-term residents (46.1% vs 64.5%), which was attenuated after adjustment (hazard ratio [HR] 0.94; 95% confidence interval [CI] 0.88–1.00), but persisted in those younger than 75 years (HR 0.82; 0.74–0.91). Compared to their respective ethnic long-term resident counterparts, the adjusted hazard of death was higher in South Asian immigrants, similar in Chinese immigrants, and lower in other immigrants (<i>p</i> value for interaction = 0.003). The adjusted hazard of vascular event recurrence (HR 1.01; 0.92–1.11) was similar in immigrants and long-term residents, and this observation persisted across all age and ethnic groups. <h3>Conclusions</h3> Long-term mortality following ischemic stroke is lower in immigrants than in long-term residents, but is similar after adjustment for baseline characteristics, and it is modified by age at the time of stroke and by ethnicity.