Prevalence of hypertriglyceridemia among Royal Thai Army personnel and its related cardiometabolic risk factors, from 2017 to 2021

In 2016, the World Health Organization reported that noncommunicable diseases (NCDs) account for 71% of the 57 million global deaths and 31% of those have cardiovascular diseases [1]. Similarly, in Thailand, NCDs are estimated to account for 74% of all deaths, with cardiovascular diseases accounting for one-fourth of them [1]. Hyperlipidemia is a well-documented risk factor for cardiovascular diseases [2, 3]. Hypertriglyceridemia is a common health problem independently associated with an increased risk of atherosclerosis cardiovascular diseases (ASCVD), including ischemic heart disease and stroke [3, 4]. Furthermore, elevated triglyceride (TG) level is an incremental risk for all-cause mortality among patients with coronary heart diseases [5].

The National Health Survey in China [6], the US [7] and Russia [8] reported the prevalence of hypertriglyceridemia (fasting plasma TG ≥ 150 mg/dL) [9] among adults aged 20 years, accounting for 13.1, 25.9, and 29.2%, respectively. In comparison, the National Health Examination Survey (NHES) in Thailand indicated that the prevalence of hypertriglyceridemia among Thai adults aged ≥ 15 years increased from 31.0% in 2014 (NHES V) [10] to 36.0% in 2019 (NHES VI) [11].

Nationwide, approximately 50,000 Royal Thai Army (RTA) personnel aged at least 35 years participate in yearly health examinations provided by the RTA Medical Department (RTAMED). However, there is little information available about hypertriglyceridemia in RTA personnel, who lead very different lives than Thai civilians. As a result, the researchers set out to identify hypertriglyceridemia among RTA personnel using the RTA personnel database of physical health examinations from 2017 to 2021. Furthermore, we explored the association between behavioral and cardiometabolic risk factors and the prevalence of hypertriglyceridemia among RTA personnel.

From 2017 to 2021, we successfully enrolled 257,683 RTA personnel between the ages of 35 and 60 years nationwide. This study represented the most extensive epidemiologic study of hypertriglyceridemia prevalence among RTA personnel in Thailand for over half a decade. Our finding demonstrates the high prevalence of hypertriglyceridemia and identifies associated behavioral risk factors, including smoking, current alcohol consumption, and sedentary behavior. Furthermore, we explored the association between hypertriglyceridemia and related cardiometabolic risk factors, including higher BMI, higher FPG, high BP, and high TC in this study population.

According to the NHES VI in 2019, the prevalence of hypertriglyceridemia in Thai adults aged ≥ 15 years was 36.0% [11]. Compared with the NHES VI, the overall hypertriglyceridemia prevalence among RTA personnel was higher (41.8%); however, the present study included participants aged at least 35 years. Furthermore, the National Health Survey in China [6], the US [7] and Russia [8] demonstrated a lower prevalence of hypertriglyceridemia among adults aged 20 years accounting for 13.1, 25.9, and 29.2%, respectively. On the other hand, we found that the prevalence of hypertriglyceridemia slightly decreased from 43.4% in 2017 to 40.3% in 2020 and then rose to 41.0% in 2021. Conversely, the NHES V in 2014 [10] and VI in 2019 [11] indicated that hypertriglyceridemia among Thai adults rose by 5% over 5 years. The present study found that the prevalence of hypertriglyceridemia among males in this study was comparable with that among Thai males in the NHES VI; however, among females, it was relatively low (19.9%) when compared with that in the NHES VI (30.7%) [11]. Our finding reported that the prevalence of hypertriglyceridemia among males was significantly higher than that among females, which was compatible with the recent evidence from the NHES VI [11] and data from the US [18], Russia [8] and Pacific Islands [19]. However, another study among hill tribes in Thailand documented that sex was not associated with hypertriglyceridemia [20].

We observed that the age of participants was associated with the prevalence of hypertriglyceridemia. Compared with male participants aged 35 to 39 years, hypertriglyceridemia among males aged 40 to 44 years was relatively high. However, the prevalence of hypertriglyceridemia among males decreased with higher age groups, especially those aged 55 years. Conversely, the prevalence of hypertriglyceridemia among females was continuously incremental with higher age groups. This pattern was similar to that of the NHES VI [11] and the population-based study in Russia [8].

We also discovered that RTA personnel residing in the northeast showed the highest prevalence of hypertriglyceridemia compared with those residing in other regions, which agreed with the findings from the NHES VI [11]. It may be explained by the cultural context of the Thai population residing in the northeast and the north consuming glutinous rice, a staple food item in this region of the country. Compared with nonglutinous rice, the staple food of the other parts of Thailand, glutinous rice has a high glycemic index and high carbohydrate content contributing to hypertriglyceridemia [20, 21]. These findings suggested that hypertriglyceridemia in RTA personnel, particularly males aged 40 to 44 years and those residing in the northeast and north, should be identified and treated to reduce the risk of coronary heart disease and ischemic stroke [5, 22‐24].

Cigarette smoking is a known behavioral risk factor for hypertriglyceridemia [25‐27]. We found that the prevalence of hypertriglyceridemia among current smokers, especially among regular current smokers, was higher when compared with those who never smoked. This phenomenon may be attributed to increased oxidative stress by the components of cigarettes, and, consequently, increased levels of triglycerides [28‐31]. Furthermore, our findings indicated that the prevalence of hypertriglyceridemia among former smokers was relatively high, which agreed with a related study in Korea [26]. Nevertheless, another study in Iran reported a reverse association between former smoking and hypertriglyceridemia (OR: 0.62; 95% CI: 0.46–0.84) [32].

Our study found that the prevalence of hypertriglyceridemia among study participants who currently consume alcohol was higher than that among abstainers. Several population studies in Switzerland, Ireland, and Korea confirmed that alcohol consumption was associated with rising plasma TG [33‐35]. On the other hand, some studies indicated a J-shaped association between alcohol consumption and plasma TG [36‐38]. A related study documented that consumption of 3 to 20 alcoholic drinks weekly was associated with lower plasma TG than consumption of more than 20 alcoholic drinks/weekly or abstainers [38]. The NHES VI reported that current alcohol consumption among Thai adults was 44.6, 59.0, and 31.0% in total, males, and females, respectively [11]. Compared with the NHES VI, our finding indicated that the prevalence of current alcohol consumption among RTA personnel (approximately 64%) was high; thus, current alcohol consumption may play an essential role in contributing to hypertriglyceridemia in this population. Furthermore, we observed that the study participants who were former drinkers were less likely to have hypertriglyceridemia. Our study suggested that alcohol consumption and cigarette smoking were potential behavioral risk factors related to hypertriglyceridemia. Thus, reducing or stopping cigarette smoking and alcohol consumption should be encouraged to attenuate the prevalence of hypertriglyceridemia and alleviate the risk for ASCVD [39‐41].

RTA personnel may be more physically active than the general civilian population. Nevertheless, the RTA has several departments with various characteristics of duty; thus, various levels of physical activities exist across our study population [11]. Our study demonstrated that the prevalence of hypertriglyceridemia among study participants who reported regular exercise was lower than that of those reporting sedentary behavior. In general, the effects of aerobic exercise were observed on reduced TG (− 12 mg/dL, 95% CI: − 16 to − 8 mg/dL among males; − 4 mg/dL, 95% CI: − 8 to 0 among females) [42]. In addition, a related randomized controlled trial indicated a beneficial effect of exercise on attenuating TG level, clearly with a high amount of moderate-to-intense exercise [43]. Therefore, our study suggested that regular exercise and progressive resistance training may be feasible to alleviate TG levels in this population [44]. However, vigorous exercise can rarely cause heat-related illness and acute coronary syndrome [45, 46], so physical exercise should be performed appropriately based on relevant evidence [47].

Multiple evidence indicated that cardiometabolic risk factors, including obesity, high FPG, high BP, and high TC, affected several cardiovascular diseases, i.e., stroke, ischemic heart disease, and atrial fibrillation [39, 48‐52]. Our findings revealed a linear relationship between hypertriglyceridemia and higher BMI. Additionally, we observed that the average TG level of study participants presenting overweight was approximately 160 mg/dL. Furthermore, the average TG level among individuals with BMI ≥ 30 kg/m², which is obese class II according to the Asia-Pacific perspective, was just below 200 mg/dL. This phenomenon could be described by abnormal triglyceride metabolism, including increased hepatic very-low-density lipoprotein production and decreased triglyceride hydrolysis, which was affected by adipocyte hypertrophy among individuals with higher BMI [53, 54]. Furthermore, the evidence documented that hypertriglyceridemia is also a hallmark of dyslipidemia in obesity [54]. Therefore, our study suggested that weight management through lifestyle change, including physical exercise and maintaining a healthy diet, should be encouraged in this population [55, 56].

We found that the prevalence of hypertriglyceridemia among the study participants with impaired FPG and hyperglycemia was significantly higher than those with FPG less than 100 mg/dL; additionally, the average TG level among individuals with FPG 150 mg/dL was elevated to approximately 250 mg/dL. A ten-year retrospective cohort study in Thailand indicated that hypertriglyceridemia was significantly associated with the incidence of type 2 diabetes (T2D) [57]. Alternatively, hyperglycemia or T2D can lead to hypertriglyceridemia via several mechanisms, including increased flux free fatty acid to the liver and decreased activation of lipases [58]. However, either hypertriglyceridemia or hyperglycemia alone suggests that they have an independent effect on the endothelial cells, contributing to the atherosclerotic process [59]. Therefore, our study indicated that primary prevention of T2D and its sequel should be promoted, especially in one-third of study participants with FPG ≥ 100 mg/dL.

We observed that RTA personnel with high BP (SBP ≥ 140 mmHg or DBP ≥ 90 mmHg) tended to have hypertriglyceridemia 1.4 times when compared with those with normal BP, which was compatible with the related studies in the US [60] and Taiwan [61]. Furthermore, the present study also demonstrated a positive association between mean TG and BP as a linear relationship. A recent animal model study indicated that hypertriglyceridemia may have enhanced resistance arterial responsiveness and increased BP [62]. The robust evidence documented that both hypertriglyceridemia and hypertension can play an independent role in increasing the risk for ASCVD [3, 39, 63]. Therefore, our results suggested that hypertriglyceridemia and high BP in this population, especially those with combined hypertriglyceridemia and high BP, should be recognized and effectively managed to prevent further complications such as stroke, ischemic heart disease, and premature death.

A significant relationship between hypercholesterolemia and hypertriglyceridemia was observed. This finding, consistent with the outcome of a related population-based study in Spain, indicated that hypercholesterolemia is the independent factor associated with hypertriglyceridemia (AOR 4.6) [64]. Evidence documented that both hypercholesterolemia and hypertriglyceridemia are independent risks for ASCVD [3, 5, 65, 66]. Furthermore, in the present study, approximately one-third of participants had a combination of hypercholesterolemia and hypertriglyceridemia. Thus, our findings suggested that this issue should be considered, and effective management such as lipid-lowering therapy may help reduce the risk for ASCVD [67]. However, nonpharmacological methods such as lifestyle modification should be initiated, as well as long-term measures to address this issue [68].

Some limitations were encountered in this study. Firstly, the study employed a serial cross-sectional design; thus, the results could present only the association between hypertriglyceridemia and related factors. Second, the present study was conducted among RTA personnel comprising a higher proportion of male participants (approximately 90%); however, the results reported a real-world situation in this study population. Third, due to the observational study using previously collected data from a health examination database, data on some variables were missing, including fasting plasma glucose (8.6%), exercise (2.4%), smoking status (1.9%), and alcohol consumption (1.7%). Although we were aware of missing data, the present study consisted of a large sample size to include the existing data in the analysis. Fourth, some variables were collected very broadly, e.g., the total number of cigarettes smoked and smoking frequency. In addition, the present study did not contain the intensity and frequency of alcohol use; thus, we cannot explore this association between the intensity of alcohol consumption and hypertriglyceridemia. Similarly, we did not have detailed data on the intensity, or type of exercise. Nonetheless, the available data provided valuable evidence regarding the associations between these behavioral factors and the prevalence of hypertriglyceridemia. Finally, regarding the existing literature that abdominal obesity contributes to an increased ASCVD [69, 70], unfortunately, waist circumference and abdominal obesity were not included in the analysis. Therefore, we do not have an opportunity to explore the relationship between abdominal obesity and hypertriglyceridemia.

Our study also encompassed considerable strengths, including representing a large sample of RTA personnel. Thus, our data provided valuable insights into the prevalence of hypertriglyceridemia and its related behavioral and cardiometabolic risk factors in Thailand. Furthermore, these data may produce strategies for the primary prevention of ASCVD and premature death in this population.

Our data demonstrated that hypertriglyceridemia is a frequent health issue, especially among males, participants aged 40 to 44 years, and RTA personnel residing in the northeast and the north. Alcohol consumption, cigarette smoking, and sedentary behavior played an essential role in the prevalence of hypertriglyceridemia in this population. In addition, cardiometabolic risk factors, including higher BMI, high FPG, high BP, and high TC, were significantly related to hypertriglyceridemia. Both behavioral and cardiometabolic risk factors are potential targets for intervention to enhance the primary prevention of sequelae of hypertriglyceridemia, including ischemic heart disease and stroke.