Immigration status, ethnicity, and outcomes following ischemic stroke

Objective: To assess the association between immigration status and
ethnicity and the outcomes of mortality and vascular event recurrence
following ischemic stroke in Ontario, Canada. Methods: 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 if the
association between immigration status and outcomes varied with age or
ethnicity. Results: We followed 31,918 adult patients, of whom 2740 (8.6%)
were immigrants, for a median follow-up of 5 years. Immigrants had a lower
mortality than long-term residents (46.1% vs. 64.5%) which was attenuated
after adjustment (hazard ratio 0.94; 95% confidence interval 0.88-1.00),
but persisted in those aged under 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 (P 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. Conclusions:
Long-term mortality following ischemic stroke is lower in immigrants and
long-term residents, but is similar after adjustment of baseline
characteristics, and it is modified by age at the time of stroke and by
ethnicity.

研究目标：评估加拿大安大略省缺血性脑卒中患者的移民身份、种族与全因死亡、血管事件复发结局之间的关联。
研究方法：本研究采用2002年至2018年的关联行政数据与临床注册数据开展回顾性队列研究，通过逆概率治疗加权法校正年龄、性别、收入与合并症因素，比较移民与长期居留居民的全因死亡及血管事件复发风险比。本研究按年龄（≤75岁与＞75岁）进行分层分析，并引入交互项评估移民身份与结局的关联是否随年龄或种族存在差异。
研究结果：本研究共纳入31918名成年患者，其中2740名（8.6%）为移民，中位随访时长为5年。移民组的全因死亡率低于长期居留居民组（46.1% vs 64.5%），经校正后该差异有所减弱（风险比（hazard ratio, HR）0.94；95%置信区间（confidence interval, CI）0.88~1.00），但在75岁以下患者中仍持续存在（HR 0.82；95%CI 0.74~0.91）。与各自种族对应的长期居留居民相比，南亚移民的校正后死亡风险更高，中国移民的死亡风险无显著差异，其他族裔移民的死亡风险更低（交互项P值=0.003）。移民组与长期居留居民组的血管事件复发校正后风险比为1.01（95%CI 0.92~1.11），组间无显著差异，且该结果在各年龄及种族亚组中均保持一致。
研究结论：缺血性脑卒中后的长期死亡率在移民群体中低于长期居留居民群体，但在校正基线特征后二者差异无统计学意义，且该结局会受脑卒中发病时的年龄与种族的影响。