10-Year Incidence Rates of Major Cardiovascular Events among Canadian Immigrant Goups

Jack V. Tu, MD, cardiologist with the Institute for Clinical Evaluative Sciences, Sunnybrook Schulich Heart Centre and the University of Toronto, presented a report on the 10-year Incidence Rates of Major Cardiovascular Events with Immigrants to Ontario, Canada at the 2013 American Heart Association Scientific Sessions.

Canada is one of the world’s most ethnically diverse countries due to high rates of immigration. Little is known about the incidence rates of cardiovascular disease in different ethnic groups living in Canada. According to Tu, information on the impact of cardiovascular disease on different ethnic groups is needed to help improve the cardiovascular health of diverse populations. Approximately 25 percent of Ontario residents are immigrants.

The objectives of the current study were to determine if there are significant cardiovascular health disparities among immigrants to Ontario, Canada, from eight major ethnic groups in regard to the prevalence of traditional cardiac risk factors, and 10-year incidence rates of major cardiovascular events.

The retrospective cohort study analyzed health data from 697,690 immigrants from 196 countries. The immigrants were identified from the citizenship and immigration information in Canada’s permanent resident database that is linked to eight population-based health databases. The study included all legal immigrants ages 30-74 that arrived in Ontario between 1985 and 1998. Study participants had to have no known history of a major cardiovascular event prior to January 2000. Immigrants were classified into one of eight major ethnic groups: White-Western European, White-Eastern European, East Asian, Black, Southeast Asian, Latin American, West Asian/Arab and South Asian.

Tu’s group found that Blacks, Hispanics, and immigrants from Russia and Iran had a higher incidence of cardiac events. Asian immigrants had a lower incidence of events.

The researchers found that the 10-year incidence rate of major cardiovascular events is lower in the immigrant groups studied compared to long-term residents of Ontario. The 10-year incidence rates of major cardiovascular disease (CVD) events varied four-fold across the eight ethnic groups. For the purposes of the study, CVD included acute myocardial infarction, stroke, congestive heart failure, percutaneous coronary intervention (PCI), coronary artery bypass graft surgery (CABG), and/or cardiovascular death.

In the summary of their results, the authors wrote that East Asian (eg, Taiwan, Hong Kong, China) immigrants had the lowest risk of CVD and South Asian (eg, Sri Lanka, Pakistan, India) males and Latin American/South Asian females had the highest risk overall. They also noted that “by country of birth, male immigrants from Guyana, Iraq, Russia and South Asian countries were at highest risk while female immigrants from Guyana, Iraq and South Asian countries were at highest risk.”

Variations in the prevalence of traditional risk factors/socio-demographic factors explain part, but not all, of these disparities. According to the authors, “Variation between ethnic groups in the incidence of the composite outcome was most explained by variation in the prevalence of hyperlipidemia (ie, total/HDL cholesterol ratio).”

This data can be used to develop health promotion strategies aimed at improving the cardiovascular health of diverse multi-ethnic populations.

Further research is needed to identify the contributions to these disparities of behavioral and lifestyle factors, as well as environmental, social, cultural, and genetic factors.

The study was supported by the Public Health Agency of Canada, the Heart and Stroke Foundation of Ontario, the Institute for Circulatory and Respiratory Health-Canadian Institutes of Health.