Atherosclerosis 150 (2000) 439 – 440
Letter to the Editor
www.elsevier.com/locate/atherosclerosis
Risk of coronary heart disease among Turkish migrants to Germany: further epidemiological evidence
Porsch-O8 zc¸u¨ru¨mez et al. [1] reported that Turkish men who immigrated to Germany 1 or 2 decades ago by now have a higher prevalence of coronary heart disease (CHD) than either Turkish men who remained in Turkey or German men [1]. Furthermore, clinical observations seem to indicate that male Turkish mi-grants have an earlier onset of severe CHD than Ger-man men [1]. These findings, if confirmed, would have major public health implications for the 2.5 million Turks living in Germany, France, the Netherlands and Austria. In their study, Porsch-O8zc¸u¨ru¨mez et al. en-rolled a cross-sectional sample of Turks residing in Germany and voluntarily participating in a check-up program. This study design has two limitations: it does not allow investigation of time trends in CHD preva-lence, and findings may not be representative for the Turkish migrant population in Germany. We here provide epidemiological evidence that partly overcomes these limitations. We obtained data on time trends and age distribution of MI mortality among all Turkish and German men aged 25 – 64 years and residing in West Germany from national registries [3]. We base our line of argumentation on the assumption that among younger men, mortality from acute myocardial infarc-tion (MI; ICD-9: 410) can be regarded as a proxy for morbidity from severe CHD. Decreases in MI mortal-ity, in turn, are interpreted as largely reflecting de-creases in coronary event rates [2].
We first look at the question of an earlier onset of severe CHD in Turkish migrants. The proportion of cases with an onset in a particular age group is affected by the age structure of a population. Table 1 shows
that the age at death from MI among Turkish men increases over the years, concurrent with an ageing of the Turkish migrant population (not shown). The peak in the number of cases in younger age groups among Turkish men as compared to Germans merely reflects a dissimilar age structure, not an earlier onset of severe CHD. Porsch-O8 zc¸u¨ru¨mez et al. postulate that with increasing length of exposure to ‘western’ risk factors Turkish migrants experienced an increasing prevalence of CHD. This should reflect in an increasing MI mor-tality over time. The age-standardised death rates from acute MI among Turkish men, however, declined by 24% since 1980 (Table 2), indicating that the high prevalence of CHD observed among participants of the check-up program is not representative for the male Turkish population in Germany. Possibly, there was a self-selection of individuals with known CHD or risk factors into the program. This notion is backed by the high proportion (70%) of previously known cases among all diagnosed CHD cases in the study sample. Epidemiological evidence thus neither supports an ear-lier onset of severe CHD as compared to German men nor an increase over time in CHD mortality among the
Table 2
Trends in death rates from acute MI, Turkish men in Germanya
Time period Crude death rate Age-standardised death rate (95% Cl)
1980–85 2.43 4.92 (4.17–5.68) 4.23 (3.83–4.63) 3.17
1986–91
3.29
1992–97 3.76 (3.52–4.00)
aDeath rates per 1000 men in the age group 25–64 years, directly
standardised in 5-year age intervals using a truncated standard world population.
Table 1
Proportion of all deaths from acute MI under 65 years by age group and time period, Turkish men in Germany and German men
B39 40–44 45–49
Age group (years) 50–54 55–59 60–64
12.1 23.5
Turks 1980–85 (%) 24.8 22.2 12.3 5.1
23.1 9.8
4.4 10.3
Turks 1986–91 (%) 31.5 20.9
4.0 4.1 11.8
Turks 1992–97 (%) 25.3 33.0 21.8
3.8
Germans 1997 (%) 4.8 8.5 13.7 28.6 40.6
Letter to the Editor 440
male Turkish migrant population in Germany. Con-versely, Turkish men currently seem to benefit from the decreasing CHD incidence and an improving clinical treatment of cases in Germany. With their study, Porsch-O8 zc¸u¨ru¨mez et al. made a valuable contribution towards a better understanding of the particular blood lipid patterns present in the majority of the Turkish population. However, in the presence of selection bias, conclusions about the prevalence of CHD among the Turkish population in Germany from participants of the check-up program should be drawn with care. Ultimately, only an analytical epidemiological study controlling for risk factor levels at the time of immigra-tion and for duraimmigra-tion of stay will allow investigaimmigra-tion of the development over time of CHD risk among Turks migrating to western Europe.
References
[1] Porsch-Oezcueruemez M, Bilgin Y, Wollny M, et al. Prevalence of risk factors of coronary heart disease in Turks living in Germany: The Giessen study. Atherosclerosis 1999;144:185 – 98.
[2] Tunstall-Pedoe H, KuuIasmaa K, Mahonen M, Tolonen H, Ruokokoski E, Amouyel P. Contribution of trends in survival and coronary-event rates to changes in coronary heart disease mortality: 10-year results from 37 WHO MONICA project popu-lations. Lancet 1999;353:1547 – 57.
[3] These data are not routinely available and had to be compiled with the help of the Statistical Offices of the 11 federal states of West Germany. Data collection was supported by a grant from Deutsche Krebshilfe, grant number 70-2364-Ze I.
Oliver Razum
Department of Tropical Hygiene and Public Health,
Heidelberg Uni6ersity,
Im Neuenheimer Feld 324,
D-69120 Heidelberg,
Germany
E-mail: oliver.razum@urz.uni-heidelberg.de
Hajo Zeeb
Department of Epidemiology and Medical Statistics,
Uni6ersity of Bielefeld,
Bielefeld,
Germany
.
