Prevalence of risk factors of coronary heart disease in Turks living in Germany: The Giessen Study

Abstract

Turkish people represent the majority of immigrants in Germany. Even though a high proportion of Turks has been living in Germany since about 20 years, little is known about risk factors of coronary heart disease (CHD) in this population. In this study a sample of 325 male and 155 female Turks are investigated, who voluntarily underwent a health check-up in Germany. Data about the presence of CHD, risk factors and blood parameters were collected. Mean residence time was 21 and 17 years (males/females). A low percentage of female participants was observed compared to the general Turkish population in Germany. Age adjusted prevalence of CHD reached 9.5% in males and 6.7% in females, respectively. Dyslipoproteinemia (DLP) showed the highest prevalence of all risk factors investigated in both genders. Total cholesterol (TC) levels were comparable to those of other western countries and remarkably higher than reported for the population in Turkey. Besides this, low high density lipoprotein-cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) levels could be found in the majority of the sample. The highest odds ratios for CHD were estimated for stress and hypertension in males and obesity in females. It is concluded that Turkish immigrants in Germany showed an assimilation of lipid pattern to western populations. However, reasons for low HDL-C levels remain unclear. Changes in the lipid metabolism chiefly seem to contribute to the risk factor pattern of Turkish immigrants in Germany.

Introduction

Coronary heart disease (CHD) is the most important cause of death in the industrialized countries. Epidemiological studies brought evidence for a tight linkage between the appearance of CHD and distinct concurrently occurring factors [1]. The major risk factors of CHD, i.e. diabetes mellitus, hypertension, smoking, and dyslipoproteinemia (DLP), are influenced both by environmental and genetic factors.

Evidence for genetically determined susceptibility for CHD is derived in particular from migration studies. Indians, for instance, are susceptible for the manifestation of glucose intolerance, DLP and, subsequently, for CHD. A marked increase in CHD was observed after migration of Indians to more industrialized regions such as Great Britain or Singapore [2], [3], [4].

Interest was focused on the Turkish population, which showed both a remarkable migration within Turkey from rural towards urban regions and a high migration rate to more industrialized countries like Germany during the past three decades.

Since the early 1960s a continuous migration of Turkish people to Germany occurred. These Turks, in the beginning predominantly males, underwent a physical examination by German physicians in Turkey before emigration. Thus, Turks migrating to Germany were a healthy, young population between the ages 20 and 30 at the time of immigration. In 1994 about 1 900 000 Turks [5] lived in Germany, including wives having followed their husbands, and their offspring.

In the 1980s there was increasing evidence that the prevalence and incidence of CHD increased dysproportionally in this population as compared to those Turks remaining in Turkey [6]. Angiographical findings also brought evidence for an earlier onset of CHD and a more severe disease in Turks living in Germany as compared to Germans (unpublished observations of the authors). A few years ago the first valid data concerning CHD morbidity rates of the Turkish population in Turkey were published [7]. Yet, there are no data available concerning the incidence of CHD and its risk factors in the general population of Turks living in Germany.

Investigators in Turkey and Germany found low high density lipoprotein-cholesterol (HDL-C) levels in Turks independent of their geographic origin or socio-economic status as a possible predisposing factor for CHD [8], [9]. In addition, a positive correlation between socio-economic status and total cholesterol (TC) levels was observed in Turkey [10]. In keeping with this observation, it was reported that meat consumption is significantly higher in urban regions in Turkey. A survey of alimentary habits of Turks living in Berlin, which is known for having a high percentage of Turkish people, found a 4-fold higher intake of meat compared to those living in Turkey [11].

A cross sectional study was conducted to obtain data about the risk factor status of Turks living in Germany. For this purpose a sample of 480 Turks older than 34 years were investigated, who voluntarily participated in a health check-up program provided by the German health authorities (so-called Check-up ’35) [12]. The survey was performed within a period of 2 years. All examinations were mainly considered as a primary prevention emphasizing the detection of CHD, diabetes mellitus, renal disease and DLP. The Check-up ’35 program was initiated in 1989 by German health authorities providing examinations in 2-year intervals. Within the first 2 years only 20% of all entitled Germans underwent this examination indicating the poor interest of the general population in primary prevention. All data concerning the Check-up ’35 are collected by the ‘Zentralinstitut für die kassenärztliche Versorgung in der BRD’ (ZI), Köln and published every 2 years [13].