There are few data on the health behavior of "Aussiedler", second largest migrant group in Germany. The analysis presented here represents a first attempt to identify the risk factors of fatal cardiovascular diseases, to quantify their effects among Aussiedler, and to compare the risk factor prevalences with that of the native German population, in order to provide an explanation why earlier studies have shown a lower cardiovascular disease mortality in Aussiedler compared to native Germans.
Major risk factors for cardiovascular diseases are known (see, for example, [37
]). In this study, these risk factors were confirmed to be also relevant in the group of Aussiedler. The results on risk factors and the magnitude of their effects are largely consistent with earlier studies on risk factors for this disease. The occurrence of stroke, diabetes mellitus, cancer, circulatory disturbances, and circulatory problems in the legs, heart disease and high cholesterol levels was significantly higher within cases in comparison to controls. The difference with respect to smoking habits and total alcohol consumption between cases and controls is also significant. Differences were also evident in the diet between cases and controls e.g. cases consumed significantly more meat and meat products.
Comparing the univariate with the adjusted ORs (Table ), confounding of major risk factors was observed, resulting in reduced adjusted ORs, for example in the consumption of alcohol (OR = 5.61 vs. OR = 3.52). The effect of several other factors, for example physical activity, was no longer significant. The observed finding of a reduced risk with low consumption of sweets must not be overinterpreted. It could be a chance finding, or it is also possible that low sweet consumption is associated with several factors which all contribute to CVD risk, such as consumption of more healthy foods, physical activity, and also of BMI. Regarding alcohol, a moderate consumption has consistently been shown to be protective, and only high consumption is associated with an increased risk. Our sample is too small to perform detailed dose-response analyses, and since we can assume some underreporting of the true alcohol consumption, we think that the cutpoint chosen is appropriate for categorising doses with a high risk.
The comparision of major risk factors to that of the native German population showed a lower prevalence for alcohol consumption. We expected a higher prevalence because of the high alcohol consumption in the former Soviet Union, especially binge drinking. It appears that this is not the case. Strobl and Kühnel also found generally low alcohol consumption among Aussiedler with the exception of adolescents [38
]. Smoking appears similarly distributed in men, and with a lower prevalence in females. High cholesterol also has lower prevalences in Aussiedler. For hypertension, different results were found in the literature, so that a comparison is difficult. In contrast, overweight in females and low physical inactivity are more among Aussiedler.
However, due to the small sample size, differences to the German reference data (Table ) are rarely significant. Overall, these results are in line with an observed lower CVD mortality in Aussiedler compared to native Germans.
However, results are in contrast to studies from the USA, Canada and Sweden, which show that the mortality of migrants is determined by the mortality in their country of origin [39
]. For Jews in Moscow, on the other hand, a lower mortality rate than the Moscow-average was determined and has been associated with certain ways of living [42
]. Although the socio-economic status, measured by conventional criteria, such as income, is lower for Aussiedler than for native Germans, there are signs that resettlers have a high satisfaction with their life [43
]. Selection with respect to the health of Aussiedler alone is unlikely to explain the observed effect of a lower mortality seen in the previous paper. However, it should be noted that there could be a selection by healthiness especially among older immigrants, while in the younger group, in which diseases are still much less obvious, this selection might be missing. It is known that subgroups may have a significantly different life expectancy than the average population, as is shown by example in different districts of Chicago where life expectancy differs up to 20 years [44
]. Whether such a big difference between Aussiedler living in Russia and local Russians exist is unknown [45
This study has a number of limitations. As a nested case-control study, it was not possible to increase the sample size and the number of cases is limited. The total number of cases is about 10% of the total members of the cohort with a CVD death. Therefore, the power to detect rare factors or factors with a moderate risk is rather low. The response rate is high among those who could be contacted by telephone, but overall relatively low. However, the rate may be underestimated because the denominator could not be given exactly. The comparison of risk factor prevalences between the Aussiedler and Germans has some limitations in the data for comparison. Some recall bias is likely, however, it is not possible to quantify this bias. Unfortunately, we don't have any data about a possible difference in healthiness or socioeconomic status between participants with or without living relatives. However, most of the controls (63%) do also have living relatives as can be extracted from the cohort data. We can also assume that several of those without a relative in our database in fact have one or more relatives, which were unknown to us. Therefore, we assume that a bias due to this aspect is small. We are aware that a possible reporting bias is one of the strongest limitations of our study. However, as is shown in the study of Nelson et al. [46
], who used a dual interview protocol in a case-control study where control subjects and their proxy respondents were interviewed, the reliability of proxy-derived data was excellent for demographic and body habitus measures and all aspects of cigarette smoking history. Proxy reliability was only somewhat lower for questions regarding medications and hormone preparations, alcolhol consumption, and recreational physical activity. The causes of death for cases are a broad heterogeneous group of conditions with possibly different sets of risk factors. Alcohol consumption is reported to be only a rather protective factor for Myocardial infarction and cerebrovascular diseases in low doses, and a high risk factor for high doses [47
]. The very high Odds Ratio for alcohol consumption (> 20 g/day in males and > 10 g/day in females) found in our study is therefore a little surprising and should be further evaluated. For this particular factor, a reporting bias must be considered. The causes of death are not based on review of medical records or adjudicated causes of death but solely on death reports and coding with its possible inaccuracies. For comparison of risk factor prevalences with the German population we used results from several earlier surveys. Although these data were not obtained in an identical way compared to this study, we think a comparison is appropriate. We have selected those surveys which we consider as most appropriate.