Ethnic inequalities in acute myocardial infarction and stroke rates in Norway 1994-2009: a nationwide cohort study (CVDNOR)

Background: Immigrants to Norway from South Asia and Former Yugoslavia have high levels of cardiovascular disease (CVD) risk factors. Yet, the incidence of CVD among immigrants in Norway has never been studied. Our aim was to study the burden of acute myocardial infarction (AMI) and stroke among ethnic groups in Norway. Methods: We studied the whole Norwegian population (n = 2 637 057) aged 35-64 years during 1994-2009. The Cardiovascular Disease in Norway (CVDNOR) project provided information about all AMI and stroke hospital stays for this period, as well as deaths outside hospital through linkage to the Cause of Death Registry. The direct standardization method was used to estimate age standardized AMI and stroke event rates for immigrants and ethnic Norwegians. Rate ratios (RR) with ethnic Norwegians as reference were calculated using Poisson regression. Results: The highest risk of AMI was seen in South Asians (men RR = 2.27; 95 % CI 2.08-2.49; women RR = 2.10; 95 % CI 1.76-2.51) while the lowest was seen in East Asians (RR = 0.38 in both men (95 % CI 0.25-0.58) and women (95 % CI 0.18-0.79)). Immigrants from Former Yugoslavia and Central Asia also had increased risk of AMI compared to ethnic Norwegians. South Asians had increased risk of stroke (men RR = 1.26; 95 % CI 1.10-1.44; women RR = 1.58; 95 % CI 1.32-1.90), as did men from Former Yugoslavia, Sub-Saharan Africa and women from Southeast Asia. Conclusions: Preventive measures should be aimed at reducing the excess numbers of CVD among immigrants from South Asia and Former Yugoslavia.