To our knowledge, this is the first study on clustering pattern of risk factors of non-communicable chronic disease in northwest China where less developed than other areas of China. We found insufficient fruit and vegetables intake led all the eight behavioral and biological risk factors we observed, followed by overweight or fat and raised blood pressure. The study also suggested that each person in northwest China had 2.13 risk factors on average and insufficient fruit and vegetable intake combined with overweight or fat, or with smoking are the two major clustering patterns. Those who are male, living in rural areas, having a lower education level and not being married increased the possibility of having more risk factors.
Our study demonstrated that more than half of the population in northwest China intakes insufficient fruit and vegetables, which was the highest prevalence among all the eight risk factors we explored. The prevalence is higher than the average Chinese national level, as well as that of the east areas of China [21, 22, 33]. Prevalence of overweight and obesity estimated in this study which ranked second was similar to the national average, while raised blood pressure ranking third was higher than the national level [22]. Northwest China is located in the semi-arid areas where vegetables and fruits are less diverse than the east and south of China. Instead of considering vegetables and fruits to be dietary necessities, noodles and mantou (a kind of steamed bread) are the staple food for local residents. Although access to vegetables and fruits are much easier due to the modern transportation, a decrease was still observed in the proportion of adults meeting the minimum recommendations for vegetables and fruits [34].
Risk behaviors related to lifestyle often established in childhood and could persist along with adulthood and they are usually hard to change without appropriate intervention [35, 36]. Compared with having no risk factors, having two risk factors increases the risk of mortality substantially [37]. And adhering to healthy behaviors decreases the risk of non-communicable chronic diseases and mortality [38, 39]. In this study, nearly two thirds of participants engaged in at least two risk factors of non-communicable chronic disease, which suggested a large number of residents in northwest China are most likely to develop non-communicable chronic diseases and mortality. Public health services and primary care system may encounter big challenges in the future.
Studies have suggested that many behavioral risk factors and biological risk factors vary concurrently [40, 41]. For instance, we found that insufficient fruit and vegetables consumption, overweight or obesity and raised blood pressure are concurrent and they are a cluster pattern of risk factors in this study. All of these three risk factors mentioned above could lead to hypertension [42–44]. Vegetables and fruit are rich in minerals, vitamins, folic acid and flavonoid, which have been suggested to lower blood pressure through benefiting endothelial function, improving antioxidant activity and modulating baroreflex sensitivity[45–48]. In addition, increased vegetables and fruits consumption might have increased dietary fiber consumption and reduced carbohydrates and fat intake. High carbohydrates and fat consumption has been demonstrated to be positively associated with risk of hypertension, as well as overweight and obesity [49–51]. The significant relationship between overweight and obesity and hypertension has been also well documented [52, 53]. As a result, public health intervention program focus only on reducing hypertension might yield little. Interventions to reduce both overweight and obesity and insufficient intake of vegetables and fruits simultaneously might therefore be mutually reinforcing and it could generate substantially larger health gains in hypertension prevention.
The findings in our study corroborates the results of China’s national level 5–8 year before that the number of risk factors increased with age, lower education level, and male, those not being married and living in rural areas reported more risk factors [15, 16]. The study in northwest China still showed that people with lower SES bear heavier burden of risk factors, both in behavior and biology. As the economy is less developed in northwest than the east, most people, especially those living in rural areas have less access to health education and primary care. Chinese government has noticed the daunting social inequality in health and a series of projects aiming to reduce it in recent years, such as Health China 2030, The Anti-Poverty, Health in China, have been implemented. These projects have become the state policy and may have numerous achievements. However, the covariation, cluster pattern and distribution of risk factors on NCDs implied that it is essential to design and implement interventions that would target a range of risk factors found in this study. The findings may contribute to the precise prevention in public health strategies.
Several limitations of the present study need to be acknowledged. First, having been adopted as indicators of Chinese national NCDs monitoring, these eight risk factors were included in this study. While some other important risk factors, such as salt intake and sleep deprivation, were not involved. Second, though BMI, blood pressure, glucose and total cholesterol, these four biological risk factors were measured or tested in laboratories, all the behavioral risk factors are self-reported and may have suspected to recall bias. Third, behavioral and biological risk factors as risk factors for NCDS were combined for analysis in this study. Their respective clustering pattern, distribution and even association with each other ought to be studied further. Finally, the income of a substantial proportion of the participants was not collected in the survey. This may have misjudged their SES.
In conclusion, the current study, together with prior studies suggests that several risk factors of NCDs are prevalent in northwest China and they are correlated. Comprehensive and integrated public health policies and interventions targeting multiple risk factors are needed, especially for those with low SES.