Among the 10,519 individuals included in the study, the average age was 51.52±8.90 years, and 53.5% of the participants were female. A significant proportion, 75.83%, had dyslipidemia, predominantly observed in the age group of 45-54 years (37.6%). The average BMI of the individuals studied was 28.14 ± 5.09 kg/m2. Based on the BMI analysis, 1.3% of participants were underweight, 26.1% had normal weight, 39.9% were overweight, and 32.7% were obese. Notably, among those with dyslipidemia, 41.2% and 35.5% were overweight and obese, respectively; highlighting a significant association between weight status and dyslipidemia in the study population. Table 1 provides a comprehensive overview of the demographic and clinical profiles of the study participants.
__Table 1__
Prevalence and number of components of dyslipidemia in all participants and by gender is shown in Table 2. Hypercholesterolemia was observed in 40.3% of participants, hypertriglyceridemia in 43.1%, low levels of HDL in 40.5%, and high levels of LDL in 29.0%. Within a subgroup of 7977 individuals with diagnosed dyslipidemia, 32.3% had a single component, 40.5% exhibited two, 20.6% showed three, and 6.7% displayed all four components of dyslipidemia.
__Table 2__
A significant relationship between BMI (both quantitative and qualitative) and dyslipidemia was observed (P<0.001) (Table 3). In the unadjusted model (Model 1), there was a positive association between BMI and the prevalence of dyslipidemia. The OR for this association was 1.09 (95% CI: 1.08-1.10), indicating that for one-unit increase in participants' BMI, the possibility of having dyslipidemia increased by 9%. The observed association between the variables remained statistically significant even after adjusting for age, gender, and other demographic variables in Model 2 and 3. The relationship between hypercholesterolemia, hypertriglyceridemia, Low HDL, high LDL and BMI with and without adjusting for demographic variables is presented in Table 4.
__Table 3__
__Table 4__
Discussion
Both high BMI and dyslipidemia all have been shown to be substantial risk factors for non-communicable diseases like cardiovascular disease, cancer, and diabetes (8). Despite the impact of these “metabolic factors” on the risk of cardiovascular disease, they are modifiable by both lifestyle changes and medical therapies, which attracts lots of research attention (15).
Our result revealed that the prevalence of dyslipidemia was 75.8%. The prevalence of dyslipidemia in developing countries is gradually increasing due to socio-economic transitions and lifestyle transformations, e.g. shifting from traditional, nutritionally balanced diets to western ones (16). The overall prevalence of dyslipidemia reported in this study is consistent with the findings in northern and southern Ethiopia (17, 18). However, our reported prevalence is higher than the findings reported in Africa (29.7 %) (19), Eastern Ethiopia (34.8%)(20), and China (43.3%) (21). The reason for the high prevalence in this study can be attributed to the difference in sample size, study environment, study population, socio-economic status, and lifestyle of the study participants.
In the unadjusted model, the possibility of having dyslipidemia increased with higher BMI; approximately, for one-unit increase in participants' BMI, the risk of having dyslipidemia increased by 9%. This relationship remained significant after adjusting for age and gender, and also for all variables. Furthermore, with the increase in BMI, the incidence rate of dyslipidemia components increased, so for one-unit increase in BMI, the number of dyslipidemia components in them increases by 2.7%. This relationship remained significant after adjusting for age and gender variables. Our finding is consistent with Yudin et al. study (12). Various studies also reported that obesity contributes to the release of large amounts of free fatty acids by lipolysis, which leads to dyslipidemia (22, 23).
The proportion of women, unemployed people, and rural people were more affected by dyslipidemia. These results were not consistent with the study of Erem et al. and Antal et al. (24, 25). But the findings of many previous studies show that women have a significantly higher prevalence of dyslipidemia (18, 26, 27). Unlike the present study, the relationship between dyslipidemia, and smoking was confirmed in different studies. Smoking may increase LDL, and TG, but decrease HDL levels, which increases dyslipidemia (28-30). Also, there was a relationship between low physical activity and dyslipidemia that it matched with Haile et al. (31), Li et al. (32), and Al zaheb et al. study (33). This can be explained by prolonged sitting, which means fewer calories are burned, may lead to calories being stored as lipids (34).
The results of this study regarding the relationship between the components of dyslipidemia and BMI showed that for one-unit increase in participants' BMI, the risk of having hypercholesterolemia and hypertriglyceridemia increased by 1 and 4%, respectively. This relationship remained significant after adjusting for age and gender variables. LDL has the same feature, but it was not statistically significant. The relationship between HDL and BMI showed that by one-unit elevation of BMI, the probability of having low HDL increased by 9%. A decrease in HDL level and an increase in triglyceride level, as abnormalities of lipid metabolism, are usually seen in obese people (35, 36). Accumulation of serum TG is caused by increased production of hepatic VLDL and decreased clearance of triglyceride-rich lipoproteins. Such an increase in production occurs due to impaired insulin signaling, which improves lipolysis and the conversion of TG to free fatty acids (FFA) in adipocytes, transporting via the blood to the liver and muscles (34). In addition, HDL metabolism is strongly associated with obesity due to the increase in the number of chylomicrons and VLDL remnants along with impaired lipolysis. Lipolysis of triglyceride-rich HDL appears due to hepatic lipase, which leads to the production of sHDL with a decrease in the affinity of Apo A-I, which leads to a decrease in HDL levels and a decrease in circulating HDL particles, thereby impairing cholesterol transport (37).
The results of this study showed that the risk of dyslipidemia was higher in the high BMI group. Therefore, weight loss should be recommended for all those with a high BMI. Also, based on the results of this research, people with dyslipidemia had less physical activity. Therefore, community-based education in the field of physical activity and sports is of great importance. Thus, BMI should be routinely assessed in primary care clinics for adults, and children to facilitate early diagnosis, evaluation, treatment of obesity, and related disorders. Therefore, the implementation of a comprehensive national public policy is urgently needed. The risk factors of dyslipidemia can be reduced by implementing healthy public policy, adequate knowledge about diabetes control factors and healthy lifestyle interventions.
The strength of this study was the examination of 10519 people who referred to the cohort of Some’e Sara County, Guilan, Iran. On the other hand, considering the referral center, the presence of trained nurses, general practitioners, specialists, and the central laboratory in the center, it can be claimed that the results of the study have great validity. In this study, only one anthropometric index was examined and other indices such as the waist–hip ratio (WHR), and waist circumference (WC) were not examined. Therefore, it is suggested that future study investigate the relationship between other anthropometric indicators with dyslipidemia.