The present study provides several insights about CVD risk factors among Chinese Han, Uygur, and Kazakh participants in Xinjiang. The results of the present study indicated that in Han participants, the age-standardized prevalence of hypertension, diabetes, obesity, dyslipidemia and smoking was 36%, 7.1%, 8.1%, 53.3% and 19.3%, respectively. In Uygur participants, prevalence of these diseases was 43.7%, 5.4%, 17.6%, 54.3% and 31.1%. In Kazakh participants, prevalence of these diseases was 54.6%, 3.4%, 24.5%, 45.9% and 35.8%. Furthermore, 9.6%, 27.4%, 28.8% and 28.4% of Han, 9.2%, 25.5%, 32.1% and 36.5% of Uygur, and 5.5%, 19.4%, 34.6% and 43.0% of Kazakh participants had none, one, two or three or more risk factors, respectively. Finally, compared with the Han participants, the adjusted odds ratios of 1, 2, and ≥3 risk factors profiles for Kazakh and Uygur participants were higher.
Several studies have noted the striking differences across ethnic groups in the prevalence of CVD risk factors in the world[15–17]. In this study, we observed that the prevalence of individual major CVD risk factors varied markedly across these three different ethnic groups. Hypertension, obesity and smoking rates were higher among Kazakh. Dyslipidemia prevalence was higher among Uygur, and diabetes prevalence was higher among Hans. Moreover, age-standardized prevalence of adverse CVD risk profiles was different across different ethnic groups. Compared with the Han participants, Uygur and Kazakh participants were more likely to have multiple CVD risk factors, reflecting the fact that all of the investigated CVD risk factors except diabetes were more frequent in Uygur or Kazakh participants.
Ethnicity is a social construct, a concept that intertwines biological, sociocultural, psychological and behavioral components. All ethnic groups can share a range of phenotypic characteristics due to the shared ancestry; the term ethnicity is typically used to highlight cultural and social characteristics such as language, ancestry, religious traditions, dietary preferences and history. The study of Latinos showed that age-standardized prevalence of CVD risk factors varied by Hispanic/Latino background, prevalence of adverse CVD risk profiles was higher among participants with Puerto Rican background, which had lower socioeconomic status, and higher levels of acculturation. Another study in India found marked differences in conventional risk factors between the Meitei and the Aggarwal, since the genetic and cultural backgrounds are different for both groups.
The mechanisms underlying the striking differences across ethnic groups in the prevalence of hypertension, diabetes, dyslipidemia, obesity and smoking are not clear. In this study, it is believed that different environmental exposures among Chinese Han, Uygur and Kazakh ethnic groups may play an important role. Beside the Han participants, the inhabited area of Chinese Uygur and Kazakh participants is relatively isolated and fixed. Most Kazakh people live as animal raisers and reside in the villages and forests north of Xinjiang, which are cold and semiarid, while most Uygur people live as farmers in the plains south of Xinjiang, which are hot and arid. Moreover, Chinese Uygur and Kazakh share similar dietary habits, characterized by drinking strong wine, eating more animal fat, a higher salt intake and consuming less grain, fresh vegetables, beans, bean products, and unsaturated fatty acids. In addition to different environmental exposures among Chinese Han, Uygur and Kazakh ethnic groups, differences in genetic backgrounds and gene-environment interactions could also be important factors underlying the different prevalence of hypertension[21–24] and diabetes. Further studies between these adverse CVD risk profiles and ethnic-specific genetic susceptibility are needed to clarify this observation.
Several studies in the United States have investigated the impact of adverse risk profiles on CVD incidence, mortality, and quality of life[26–30]. In these studies, CVD incidence and all-cause mortality increased progressively and substantially in the presence of more risk factors. For example, data from the First NHANES Epidemiologic Follow-up Study showed that the age-,race-, sex-, and education-adjusted relative risks of CVD during the 21-year follow-up in adults with one, two, three, four or five risk factors were 1.6,2.2, 3.1, and 5.0, respectively, vs. participants without any risk factor. In longitudinal studies, the presence of CVD risk factors at baseline has been associated with a diminished quality of life. These programs to enhance efforts aimed at prevention, detection, and treatment of dyslipidemia, hypertension, diabetes, smoking, and obesity may greatly reduce the future burden of CVD.
The striking differences across ethnic groups with regard to the prevalence of CVD risk factors and adverse CVD risk profiles emphasize the need for the development of ethnic-specific and cost-effective CVD prevention programs and health services to reduce the prevalence of these risk factors, as well as CVD morbidity and mortality in the Chinese Han, Uygur and Kazakh participants in Xinjiang. In addition, future public health interventions need to take into account the special needs of people living in Xinjiang. Effective interventions such as smoking cessation, improved diet (reduction of salt and fat), and increased physical activity can safely and effectively lower the risk of CVD. A multidisciplinary and targeted approach aiming at prevention, detection and treatment of hypertension, dyslipidemia, diabetes, obesity and smoking could substantially reduce the prevalence of adverse CVD risk profiles, as well as CVD morbidity and mortality.
Participants with a history of myocardial infarction, stroke, or congestive heart failure were excluded from our analyses in order to focus on the burden of CVD risk factors among patients without CVD. Nonetheless, results were markedly consistent when participants with existing CVD complications were included in the analyses. We chose not to include physical inactivity as a CVD risk factor in the current analyses because it is causally involved in the development of all CVD risk factors studied, except cigarette smoking. Inclusion of physical inactivity as a risk factor would have artificially inflated the prevalence of CVD risk factor profiles. The findings of the present study are limited to self-reported information. However, the data were age-standardized to the Chinese population in 2000 to allow for comparisons with observations from national surveys, and protocols used were similar to those of other epidemiological studies.
In conclusion, the present study demonstrated the pervasive burden of CVD risk factors in all participant groups in Xinjiang and identified specific ethnic groups at particularly high risk of CVD. These data may increase the need to implement interventions to lower the burden of CVD risk factors among Xinjiang people overall. Ethnic-specific strategies should be developed to prevent CVD in different ethnic groups, as well as strategies to prevent future development of adverse CVD risk factors starting at the youngest ages.