Risk of cardiovascular events and mortality among a population-based cohort of immigrants and long-term residents with diabetes: are all immigrants healthier and if so, for how long?

Background — Cardiovascular events are responsible for half of all deaths among individuals with diabetes. Immigrants to western countries may experience an acceleration of cardiovascular risk in the first 10 years of arrival because of a sedentary lifestyle, poor diet or barriers to accessing care, leading to higher levels of obesity and diabetes.

Objectives — To compare the risk of cardiovascular events and mortality between immigrants to Canada and long-term residents with diabetes and to assess whether immigrants experience acceleration in risk after arrival.

Methods — The researcher conducted a population-based retrospective cohort study using linked health and immigration data from Ontario, Canada of 87,707 immigrants who immigrated to Canada between 1985 and 2005 matched to 87,707 long-term residents with diabetes (age ≥ 20 years). Individuals were followed from April 1^st, 2005 until February 29^th, 2012 for the primary composite outcome of a cardiovascular event (acute myocardial infarction, unstable angina, congestive heart failure, transient ischemic attack, stroke) or all-cause mortality.

Results — There was a lower adjusted risk of cardiovascular events or mortality among immigrants (adjusted HR=0.76, 95% CI=0.74-0.78) after accounting for differences in baseline age, gender, socioeconomic status, neighborhood, and healthcare utilization – which persisted beyond 10 years from immigration. However, this healthy immigrant advantage was not found among more recent refugees (HR=0.93, 95% CI=0.81-1.08), immigrants with no previous education (HR=1.08, 95%CI=0.84-1.40), and those who were unmarried (HR= 0.80, 95% CI=0.62-1.03).

Conclusion — Immigrants with diabetes are at lower risk of cardiovascular events and mortality compared to long-term residents, an effect that persists more than 10 years after arrival. Not all immigrants demonstrate this health advantage.