Our results showed that individuals from ethnic minorities have a higher prevalence of diabetes and obesity but a lower prevalence of hypercholesterolemia and reported smoking than the native Dutch population, while the prevalence of hypertension seemed comparable between ethnic groups. Furthermore, in each ethnic group different combinations of cardiovascular risk factors were found.
The finding that diabetes was more prevalent among some ethnic groups than among the native population was also reported in other national and international epidemiological studies [15, 23–26]. In the studies by Cappucio et al. [23], Bhopal et al. [24], and Anand et al. [25], South Asians in the UK and Canada had a higher prevalence of diabetes/glucose intolerance than people of European origin; and in the study by Winkleby et al. [26] Black and Mexican American women had higher diabetes prevalence than white women. This phenomenon can be explained by genetic susceptibility and/or environmental factors such as the adoption of a western diet, obesity and physical inactivity [27].
We did not find indications for a higher prevalence of hypertension in ethnic minority people than in the Dutch population, although the diastolic blood pressure was relatively higher among ethnic minorities than among the Dutch. This result is similar to other studies showing no clear differences between Turkish or Moroccan people and the native Dutch population [15]. There are some indications of a higher prevalence among Surinamese (a mixed group of African descent and people originated from South Asia) than in Dutch [28], which is in accordance with international studies that reported a higher prevalence of hypertension in South Asians [29] and people from African origin [30] compared to white populations in the UK and USA respectively.
Hypercholesterolemia, based on the level of total cholesterol, was generally higher in Dutch than in most ethnic minority people. This is in line with the limited data comparing the Turkish or Moroccan ethnic groups with the Dutch [15] while no such information is available for Surinamese and Antilleans. On the other hand, the levels of other lipid components were more disadvantageous (e.g. high levels of triglycerides among Turks and Moroccans) among some ethnic groups in our study than in the Dutch. In general, ethnic comparisons of the lipid profiles remain difficult because of the limited number of studies and inconsistencies of the findings [15].
In line with previous studies [15, 23, 24] obesity was more common among minority groups, particularly Turkish people, than in the native population. The proportion of obese individuals in our study also largely exceeded national rates implying that obesity is a serious health problem among people living in deprived neighbourhoods and in particular among ethnic minority women. Native Dutch had a higher prevalence of reported smoking than non-Dutch groups, but Turkish men had a higher prevalence than Dutch men. This is in agreement with other Dutch studies showing a high smoking prevalence among Turkish men [15]. The low prevalence of smoking among ethnic minority women in our study is also consistent with previous national and international studies [15, 23–25].
The 10-year cardiovascular risk was higher in Dutch, but the age and gender adjusted 10-year risk was somewhat higher in ethnic minorities, which could be attributed to their unfavourable cardiovascular risk factors. Intervention activities are recommended according to the 10-year CVD risk [19]. This approach could result in under treatment of young ethnic minority groups with high levels of (modifiable) risk factors and over treatment of elderly Dutch people [31].
Some limitations of the present study should be mentioned. First, the nature of the study population. Because data collection took place among a population at risk of developing CVD, this means that our results can not be generalised to the general population due the inclusion of high-risk individuals only. However, our findings point to the same direction as previous studies in the general population, and show the necessity of tailoring interventions also in this high-risk group. In addition, for the prevention of CVD, evidence has shown that targeting high-risk groups is more beneficial than targeting the general population [32]. The response rate was 47% which is satisfactory when taking into account previous studies conducted in multi-ethnic patient populations in the Netherlands [15]. We have no reason to believe that the cardiovascular risk factors are likely to be different in the individuals examined compared to those who were not because responders and non-responders in our study had a comparable cardiovascular risk profile according to GP medical records.
Since we firstly selected patients from the electronic GP medical records, our findings could be biased because of differences in access to the general practice or in the registration of risk factors between the general practitioners. Regarding access to the general practice, in the Netherlands (almost) all patients are registered in a general practice and therefore have equal access regardless of where they live. Concerning registration of risk factors, we used all available medical information from the GP medical records to identify potential high-risk patients. This yielded similar proportions of potentially high-risk individuals per general practitioner, indicating that an effect of differences in registration between the general practitioners is unlikely.
This study shows the heterogeneity of people living in deprived neighbourhoods in terms of ethnicity, demographic and socioeconomic characteristics, and particularly the distribution of cardiovascular risk factors which emphasizes the need for tailoring interventions to different ethnic groups at risk of developing CVD. Notably, attention should be given to diabetes intervention and education, since diabetes is one of the most prevalent cardiovascular risk factors among all ethnic minorities at risk of developing CVD, particularly the Moroccans. Among the Turks emphasis should be put on interventions aimed at reducing the high prevalence of obesity as well as smoking while among the Dutch hypercholesterolemia and smoking should be given higher priority than other risk factors. We found no ethnic differences in hypertension; however, taking into account previous studies we suggest that interventions with regard to Surinamese and Antilleans should take hypertension into consideration.
In conclusion, the present study shows that the different cardiovascular risk factors were not uniformly distributed among ethnic groups in the Netherlands and provides additional evidence of the need to tailor interventions for different ethnic groups in general practices.