Immigration, myocardial infarction, and type 1 diabetes in Sweden : use of the migration and health cohort

Abstract

The aim of this study was to examine the risks for and time trends of first-time myocardial infarction and type 1 diabetes mellitus, and the equity of admission to specialized care and evidence-based treatments after first-time myocardial infarction in association with country of birth, socioeconomic position, sex, and age.

The Migration & Health Cohort was used in all four papers. This cohort was built by linkage between Swedish national registers to study the incidences of cancer, diabetes, injuries, and cardiovascular and psychiatric diseases among immigrants and their descendants compared with Sweden-born residents. Poisson regression was used to estimate incidence rate ratio of first-time myocardial infarction and type 1 diabetes mellitus, logistic regression for odds ratio of admission to coronary care units, and Cox proportional hazard regression to model first-time myocardial infarction case fatality and likelihood of undergoing cardiac procedures.

First, during more than two decades of follow-up of all men and women aged 35–89 years living in Sweden, we identified 571,476 patients with first-time myocardial infarction (Paper I). We observed a decreasing trend in incidence and case fatality after day 28 for both sexes regardless of country of birth. The trend was, however, less pronounced among women and those born outside Sweden. Men born in Southern and Western Asia had a 50% higher risk than men born in Sweden. Incidence was 50–80% higher in the least well educated irrespective of sex and country of birth.

Secondly, between 2001 and 2009 we identified 120,609 first-time myocardial infarction patients treated in a coronary care unit (Paper II). A low rate of coronary care unit admission after first-time myocardial infarction among women and patients of low socioeconomic position was observed. Foreign-born patients, both men and women, were equally likely to be admitted to coronary care units as Sweden-born patients.

Thirdly, we followed first-time myocardial infarction patients admitted to coronary care units between January 2001 and September 2009 for 90 days after admission (Paper III). In total, 61.71% of patients underwent angiography, 45.74% underwent percutaneous coronary intervention, and 9.15% underwent coronary artery bypass grafting. Foreign-born patients were no less likely to undergo these procedures than Sweden-born patient. Furthermore, patients born in Asia had a high rate of access to coronary artery bypass grafting.

Fourthly, we followed 4,469,671 men and 4,231,680 women, aged 0 to 30 years, living in Sweden at any time between 1969 and 2008 (Paper IV). Over the study period, the risk of type 1 diabetes mellitus increased among children younger than 15 years, but not among young adults (15–30 years). Compared with Sweden-born individuals, immigrants aged 0 to 14 had about a 40% lower risk of type 1 diabetes mellitus, and the risk was about 25% lower in the offspring of immigrants. Further, immigrants aged 15 to 30 years had about a 30% lower risk, and the offspring of immigrants about a15% lower risk of type 1 diabetes mellitus compared with their Sweden-born counterparts.

Country of birth is associated with risk of first-time myocardial infarction and type 1 diabetes mellitus. First-time myocardial infarction risk is decreasing in all age groups but type 1 diabetes mellitus is increasing among children less than 15 years of age. Immigrants in Sweden are not disadvantaged in terms of accessing cardiac care after first myocardial infarction, in contrast to women and patients with low socioeconomic position.