Cardiovascular disease and ethnicity: Focus on the high risk of CVD among South Asians living in Norway and New Zealand

Abstract

The burden of cardiovascular disease (CVD) among immigrants in Norway has not been described previously. Our knowledge about cardiovascular risk factors is largely based on information from European populations. Thus, the role of cardiovascular risk factors for the increased risk of CVD in South Asians is unclear.

An overall aim of this thesis was to study the burden of CVD among immigrants in Norway using data from the Cardiovascular Disease in Norway (CVDNOR) project, with information from all Norwegian hospitals and the Cause of Death Registry during 1994-2009. Another aim was to study the prospective relationships between major risk factors and subsequent CVD in South Asians and Europeans, and examine to what extent these risk factors could explain any potential differences in CVD between South Asians and Europeans. Information about risk factors from Norwegian health surveys and risk factor data from the primary health care in New Zealand were linked with hospital and mortality data to study the role of cardiovascular risk factors in South Asians and Europeans. A final aim was to validate a well-known Framingham prediction model to see how well it predicted the risk of CVD in Indians versus Europeans in New Zealand.

The burden of cardiovascular disease differed between immigrant groups in Norway. South Asians had more than double the risk of myocardial infarction compared to Norwegian-born, and an increased risk of stroke. Immigrants from the Former Yugoslavia also had an increased risk of CVD, while immigrants from East Asian countries had reduced risk of myocardial infarction compared to Norwegian-born. Diabetes and cholesterol partly explained the increased risk of CVD in South Asians in Norway and New Zealand. The Framingham model predicted the risk of CVD reasonably well in Indian men in New Zealand, but overestimated the risk in Indian women and in European men and women.