This study investigated hyperlipidemia and related risk factors in urban adults aged 35–79 years in Chengdu and Chongqing from September 2013 to March 2014, based on a population in southwest China. In general, the average prevalence of dyslipidemia was 27.4%, which increased with age, and the prevalence of dyslipidemia was higher in men (30.2%) than in women (25.9%). The higher prevalence rate in men may be related to the higher income, smoking rate, drinking rate, WC, hypertension prevalence rate, SBP, and DBP level. But interestingly, the prevalence in women was lower than that in men under the age of 55, and it was higher in women later in life than in men. Moreover, with the increase of age, TG, TC, and LDL-C levels in women showed a significant increasing trend. This result was consistent with other studies9,12. This may be related to differences in estrogen levels in women before and after menopause12. However, in Table 4, multivariable analysis showed that dyslipidemia was unrelated to age and gender. This may be due to controlling for other factors, including mediators, to block the effect of age and sex on dyslipidemia.
From January 2007 to October 2010, China's national chronic kidney Disease survey13 showed that the prevalence of dyslipidemia in Chinese adults was 34.0%9, 13753/40486. It can be seen that the prevalence of dyslipidemia in southwest China is slightly lower than the average level of Chinese adults. Besides, the prevalence of dyslipidemia (27.4%) and lipid levels (TG1.3 mmol/L and TC4.6 mmol/L) in southwest China were relatively low compared with other regions in China as previously reported. For example, the cities with relatively developed economy,such as Beijing14(prevalence of dyslipidemia 35.4%, TG1.53 mmol/L, TC5.05 mmol/L), Shanghai12 (prevalence of dyslipidemia 36.5%), Shenzhen15 (prevalence of dyslipidemia 34.72%, TG1.44 mmol/L, TC4.77 mmol/L), as well as Jilin16 (prevalence of dyslipidemia 62.1%) and Shandong17 (prevalence of dyslipidemia 45.8%) in the north. The distribution of dyslipidemia has obvious economic and regional differences. This may be related to the following reasons: 1) The economically developed Regions of Beijing14, Shanghai12 and Guangzhou15 have higher living standards, and their lifestyles and consumption of western food are close to those of developed countries; 2) The cold climate in the northern region leads to an increase in the intake of animal fats and a decrease in the intake of fresh fruits and vegetables, while the cold weather restricts people's outdoor physical activity, thus increasing the risk of obesity or overweight and related metabolic abnormalities16,17. Also, Chengdu is the capital of Sichuan Province, compared with the epidemiological survey of dyslipidemia in Sichuan18 in 2002, the prevalence of dyslipidemia was increased to a certain extent (22.49, 484/2152% VS 27.4%, 2796/10221), and the lipid levels were also increased, TG and TC levels were 1.14, 3.76 mmol/L VS1.3 and 4.6 mmol/L, respectively. These increases are consistent with the rapid economic development and lifestyle changes in the southwest region in recent years. We found that the current prevalence of dyslipidemia and lipid levels in the southwest people aged 35-79were relatively low compared to the rest of the country. Dyslipidemia is the main pathogenic factor of atherosclerosis and one of the independent risk factors of cardiovascular diseases such as coronary heart disease6and stroke7. This also indicates that the prevention and treatment of dyslipidemia in southwest China will face challenges in the future.
At the same time, we found that the prevalence rates of high TG, high TC, low HDL-C, and high LDL-C in people aged 35–79 years in southwest China were 15.7%, 5.4%, 5.7%, and 2.5%, respectively, while the prevalence rates of high TG, high TC, low HDL-C and high LDL-C in Chinese adults9 were 12.17%, 7.50%, 15.31%, and 7.96%, respectively. Therefore, high TG was the main type of dyslipidemia in southwest China. The prevalence of high LDL-C was much lower in southwest China. Previous studies have shown that the LDL-C level is the indicator most closely related to ASCVD risk19,20. One research21 analyzed data of 219,522 Chinese patients with type 2 diabetes and found that there were large regional variations in the prevalences and risks of coronary heart disease and stroke in T2DM in China. Southwest China had the lowest prevalence of both CHD and stroke in Chinese adults with type 2 diabetes. Another nationally representative survey22 included 480687 adults aged ≥ 20 years demonstrated the lower prevalence of stroke in Southwest China. Despite its large population and high GDP, Southwest China had a low-ranking number of percutaneous coronary intervention23. Interestingly, contemporaneous studies24,25 showed that the prevalence of hypertension(38.4%) and diabetes༈19.5% ༉in the Southwest was no lower than the national average༈hypertension 32.5%26,diabetes 9.7%27༉. Therefore, it is reasonable to speculate that the low prevalence of dyslipidemia and low LDL-C contribute to the lower ASCVD prevalence in southwest China. However, due to the diversity of ASCVD risk factors and the limitations of cross-sectional studies, further studies should be expected.
This study also analyzed the correlation between dyslipidemia and various factors. In addition to the common risk factors associated with dyslipidemia10,24, such as smoking, hypertension, and diabetes, this study also showed a positive correlation between a high school degree or above, a monthly income of more than 2000 yuan, and the prevalence of dyslipidemia. This may be due to the better economic and nutritional status of people with higher education and income25. Overweight, obesity and central obesity are correlated with dyslipidemia, suggesting that BMI and waist circumference can be used as screening indicators for dyslipidemia, and weight control is an important prevention and control method26,27. Besides, dyslipidemia was negatively correlated with daily physical exercise, suggesting that strengthening physical exercise is also an important method for the prevention and control of dyslipidemia.
In conclusion, our study provides the latest and reliable information for dyslipidemia in southwest China. The results show that the prevalence of dyslipidemia in southwest China was lower than the national average but on the rise. High TG was the main type of dyslipidemia, and the prevention and control of dyslipidemia are faced with challenges. Dyslipidemia is closely related to smoking, hypertension, diabetes, higher education, higher income, obesity, and central obesity. Only by strengthening public health education and intervening in risk factors can we face the challenge.