BARCELONA – In what is being called “the healthy immigrant effect,” Canadian investigators have found that adult diabetic immigrants from low-income countries with high cardiovascular mortality rates are relatively protected against cardiovascular events, compared with matched long-time or lifetime Canadian residents. This healthy immigrant effect appears to last for at least a decade following the immigrants’ arrival in their new land, and perhaps longer, Dr. Karen Okrainec reported at the annual congress of the European Society of Cardiology. Ontario is fertile territory in which to study the health of immigrants. Fully 43% of Ontario residents are foreign born, the highest proportion in all of Canada’s provinces, noted Dr. Okrainec of the University of Toronto.
She presented a population-based cohort study involving 87,707 adult diabetic subjects who immigrated to Ontario during 1965-2005 and an equal number of long-term or lifetime diabetic Ontario residents matched for age, sex, and neighborhood. Most of the immigrants came from South Asia and East Asia, although there were also significant numbers from the Caribbean, Sub-Saharan Africa, North Africa, and the Middle East, and Eastern and Western Europe. The immigrants had been in Canada for a mean of 11.6 years at the time of the analysis.
The primary outcome in the study was the composite endpoint of all-cause mortality or one or more hospitalizations or emergency department visits for acute MI, heart failure, unstable angina, stroke, or TIA between April 2005 and February 2012. There were 13,685 of these events among the immigrants, for an event rate of 2.4 cases/100 person-years.
This was fully 32% lower than the unadjusted event rate among the control group.
After researchers adjusted for years since diagnosis of diabetes, education level, income, the presence of hypertension, and other comorbid conditions, language barriers, marital status, and other potential confounders, they found that the risk of the composite endpoint remained 24% lower in immigrants than controls. Thus, it is clear there is not an accelerated risk of cardiovascular events among diabetic immigrants, despite their change in lifestyle in moving to a highly developed country where they may encounter cultural or language barriers to health care access, according to Dr. Okrainec.
Not all immigrants benefited from the healthy immigrant effect, however. Refugees did not. Neither did those who were single, nor did immigrants from Eastern and Central Europe or Latin America. Also, the healthy immigrant effect – the diabetic immigrants’ health advantage over longer-term Ontario residents – appeared to grow stronger with time; in other words, the healthy immigrant effect was weaker in those who arrived in Ontario less than 10 years earlier.
Dr. Okrainec’s study was funded by the Ontario Ministry of Health and Long-Term Care. She reported having no financial conflicts.