The primary finding of the current study was the very high prevalence of dyslipidemia in women aged 35–70 years of the PERSIAN Bandare Kong Cohort Study, with 84.8% of the study population having at least one type of lipid abnormality based on ATP III criteria. High TC was the most common (53.9%) followed by low HDL (50.8%), high LDL (48%), and high TG (26.2%).
Prevalence of dyslipidemia in women was 87.7% in Najafipour et al.'s study (29), 61.3% in the study by Ebrahimi et al. (30), 85.1% in Latifi et al.'s study (31), 80.4% in a study on Turkish adults (32), and 37.6% among Chinese women (2). In a systematic review and meta-analysis conducted by Tabatabei et al. on the prevalence of dyslipidemia in published articles until September 2011, hypercholesterolemia, low HDL, and high LDL were more prevalent in women compared to men (13). Esteghamati et al. showed that the prevalence of hypertriglyceridemia and hypercholesterolemia were 33.2% and 45.4% among females (33). The corresponding percentages were 41% and 23% in Japanese women aged 25–64 years (34), 25% and 37.2% in Turkish adults (35), 24.1% and 30.6% in Najafipour et al.'s study (29), and 65.1% and 47.5% in Latifi et al.'s study (31). The variety of the prevalence of dyslipidemia and its individual components across different studies can be explained by demographic, socioeconomic, and anthropometric features of study populations which will be discussed in details later on.
The results of this study showed that the prevalence of dyslipidemia steadily increased with age in women up to the age of 54, with an abrupt but slight decrease in the 55–59 age group, but it increased again thereafter probably due to hormonal changes during menopause. A similar trend was observed in Ebrahimi et al.'s study (30). Nonetheless, we found no significant increase in the odds of dyslipidemia with age based on the logistic regression analysis. Yet, other studies in different parts of the world have shown that the risk of different types of dyslipidemia increases with age in both men and women (35–37).
We found no correlation between marital status and dyslipidemia or any of its components, which was in line with the findings of Ebrahimi et al. (30). Whereas, aside from low HDL, other lipid abnormalities were higher in married and widowed individuals compared to singles in the study by Erem et al. (35).
According to the findings of the current study, having a high school diploma was protective against dyslipidemia; however, there was no significant association between the level of education and individual components of dyslipidemia. Quite similarly, dyslipidemia was not influenced by level of education in a study conducted in India (10). In addition, this was partially consistent with the results of Ebrahimi et al.'s study, in which no relationship was found between the risk of developing different types of dyslipidemia and the level of education (30). On the contrary, Erem et al. in their study to estimate the prevalence of dyslipidemia and associated factors among Turkish adults, demonstrated that the risk of dyslipidemia was higher in those with lower education level. They justified their findings by higher exposure to risk factors such as poor eating habits and working conditions, difficulty to access health services, and stress in those with low level of education (35). Of note, the findings of the above-mentioned studies were with respect to both men and women. Results can be different when only women are concerned.
We found that women living in rural areas were at significant decreased risk of developing dyslipidemia, low HDL, and high LDL. The odds of hypertriglyceridemia and hypercholesterolemia, although insignificant, was also lower in women living in rural areas. Conversely, Cui et al. demonstrated that the prevalence of hypercholesterolemia was higher in rural areas compared to urban areas for women (34). Similarly Tripathy et al. demonstrated that living in rural areas increased the risk of dyslipidemia and high TC (38). The reason for these inconsistencies may be the consumption of fat-rich foods such as high-fat dairy by individuals living in rural areas in the two studies.
Over the past decade, there has been a decline in consumption of traditional foods, while use of high-fat, high-calorie, low-fiber, and processed foods has increased. This unhealthy diet together with insufficient physical activity, are risk factors for obesity and hypertriglyceridemia (39–41). Among the participants of the current study, 39% were overweight and 30.5% were obese. Overweight and obesity were only significantly correlated with hypertriglyceridemia but not dyslipidemia or other lipid abnormalities. Among the anthropometric indices, high WHR was the best predictor of dyslipidemia and all of its components. Obesity has been reported to be associated with hypertriglyceridemia in many studies (9, 10, 35–37, 42, 43). It should be noted that contrary to our findings, obesity has been proposed as a risk for hypercholesterolemia in some studies (9, 10, 35, 42).
The odds of hypertriglyceridemia was significantly higher in women with hypertension in our study, while neither dyslipidemia nor any other components were associated with hypertension. This was in agreement with the findings of Ebrahimi et al.; however, they also reported a significant correlation between high blood pressure and dyslipidemia (30). Tabrizi et al. reported similar results (44). Despite comparable findings regarding the association between hypertension and hypertriglyceridemia in a study in India, dyslipidemia and other lipid abnormalities were also significantly correlated in this study (38).
One limitation of the current study was that although, lipid-lowering medications were taken into account, some women with diabetes may have failed to indicate that they were taking these agents, which resulted in contradictory findings regarding the relationship between dyslipidemia or its components with diabetes. Another limitation was the assessment of physical activity which was reported in METs. The positive effect of physical activity on serum lipids, plasma glucose, and many other CVD risk factors has been previously established; therefore, the increase in TC and LDL with higher weekly METs observed in the current study can in part be due to inaccurate evaluation of physical activity. One more limitation was the daily calorie intake that was not subdivided based on specific foods. Calorie content of fat-rich foods would have been more valuable in the assessment of the correlation between lipid abnormalities and daily calorie intake.