2025 年 32 巻 7 号 p. 786-803
Aims: To investigate the association between triglyceride levels and major adverse cardiovascular events (MACE) in primary and secondary prevention cohorts.
Methods: This retrospective study was conducted with a nationwide health insurance claims database, which included approximately 3.8 million participants with medical checkups between January 2005 and August 2020 in Japan. The participants were classified into primary prevention (n=3,415,522) and secondary prevention (n=29,806) cohorts based on cardiovascular or cerebrovascular disease history. Each participant was categorized as having very low (triglyceride <50 mg/dL), low normal (50–99), high normal (100–149), or hypertriglyceridemia (≥ 150). The primary prevention cohort was further stratified into low-, intermediate-, and high-risk groups according to atherosclerotic cardiovascular diseases risk. Outcome was MACE, including acute myocardial infarction (AMI), unstable angina, ischemic stroke, and cardiac death.
Results: Over a mean follow-up of 3.25 years, 0.3% and 2.6% MACE occurred in primary and secondary prevention, respectively. Hypertriglyceridemia was associated with high risk of MACE in the primary prevention, but not in the secondary prevention. A significant interaction was observed between prevention categories and the association of TG levels with MACE in those with TG <150 mg/dL and ischemic stroke in those with TG ≥ 150 mg/dL. The population-attributable fraction for hypertriglyceridemia in primary prevention was 4.1% for MACE. In primary prevention, lower risks of AMI were observed in the lower TG category compared to the current threshold.
Conclusions: This study suggests distinct triglyceride thresholds for MACE risk in primary and secondary prevention cohorts, requiring further prospective validation for clinical implementation.
Hiroyuki Mizuta and Masanobu Ishii contributed equally to this work.
See editorial vol. 32: 783-785
Managing dyslipidemia, particularly elevated low-density lipoprotein cholesterol (LDL-C), is key to preventing atherosclerotic diseases such as coronary artery disease (CAD) and ischemic stroke1-3). Statin therapy is a standard treatment for lowering LDL-C, and reports indicate that further reductions in LDL-C decrease major cardiovascular events (MACE) risk, without any observed threshold4, 5). Add-on or alternative drugs to statins, including ezetimibe, bempedoic acid, PCSK9 inhibitors, further diminish cardiovascular risk6-10). Although LDL-C lowering therapy is effective, there are residual risks from other lipids like triglycerides (TGs)11-15).
TG-lowering therapy utilizing fibrates and niacin exhibits a mild LDL-lowering effect; however, previous randomized controlled trials (RCT) do not provide substantial support for their adjunctive use alongside statin therapy12, 16). The JELIS and REDUCE-IT trials demonstrated the effects of eicosapentaenoic acid (EPA) administration on MACE, which might not be explained solely by the effect of lowering TG17, 18). These evidences regarding TG-lowering therapy for MACE prevention is controversial in the statin era12, 16-18). A key aspect of this controversy lies in the potential variability of optimal TG thresholds for cardiovascular event reduction, which may differ between risk categories. While LDL-C targets are stratified by prevention type and risk level, the guidelines apply a uniform threshold of TG levels across both primary and secondary prevention19-22). This uniform approach raises the question of whether a more tailored, risk-based TG management strategy is needed.
This study aimed to investigate the association between TG levels and the risk of atherosclerotic events and the interaction between those risks and prevention categories using a nationwide database.
The study protocol was approved by the Institutional Review Board of Kumamoto University Hospital (Rinri No. 2666) and was conducted in accordance with the principles outlined in the Declaration of Helsinki. The need for informed consent from the individual participants was waived because all data were de-identified (anonymized). This study adhered to the STROBE reporting guideline for observational studies.
Study Design, Participants, and SettingsThis study was a retrospective analysis of the Japan Medical Data Center (JMDC) Claims Database, which is a nationwide health insurance claims database. It comprises de-identified individual healthcare records (inpatient, outpatient, dispensing) including demographic details, diagnoses categorized under the International Classification of Diseases, 10th Revision (ICD-10) coding, medication information, medical procedures, mortality data, hospitalization events, and annual health checkup data for workplace employees, inclusive of blood pressure readings and lipid profile laboratory results from multiple health associations, as well as Specific Health Checkups23-26). Between January 2005 and August 2020, 3,824,093 participants who underwent a comprehensive medical checkup with measurement of lipid profiles such as LDL-C, high-density lipoprotein cholesterol (HDL-C), and TG were enrolled. Of these, analyzed population (n=3,445,328) was identified after exclusion of participants who had missing values of past histories (n=269,788) and data for antihyperlipidemic medications (n=108,977). The participants were classified as the primary prevention (n=3,415,522) and secondary prevention cohort (n=29,806) based on the prior history of cardiovascular disease such as angina pectoris, myocardial infarction, or coronary revascularization, and cerebrovascular disease such as ischemic stroke, or intracranial hemorrhage (Supplementary Fig.1).

JMDC indicates Japan Medical Data Center.
During the health check-up, blood samples were collected from each participant who had fasted for more than 10 hours. Blood laboratory test data, such as TG, LDL-C, HDL-C, glucose, and hemoglobin A1C levels at the initial health checkup, were used for exposure. The TG category was divided into: 1) two groups using a cut-off value of 150 mg/dL based on current guidelines19-21), or 2) four groups as follows: very low (<50 mg/dL), low normal (50–99 mg/dL), high normal (100–149 mg/dL), or hypertriglyceridemia (≥ 150 mg/dL), as previously reported27) with tailored modifications. Following >5 min of seated rest, the brachial blood pressure was measured twice with a >1-min interval while an average of 2 measurements was used for analysis23, 28). Hypertension was defined as systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg, or the use of anti-hypertensive agents23, 28). Diabetes mellitus was defined as a fasting plasma glucose level of ≥ 126 mg/dL or the use of anti-diabetic agents23, 24). Body mass index (BMI) was calculated as weight (kg) divided by height squared (m2). The BMI categories were defined as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5 to <25 kg/m2), overweight (BMI 25 to <30 kg/m2), and obesity (BMI ≥ 30 kg/m2). The original questionnaire regarding smoking and alcohol consumption has been previously reported29). Briefly, current smoking status was assessed with the question: “Are you a current regular smoker?” (defined as having smoked 100 or more cigarettes or for at least six months, and currently smoking). Alcohol consumption was assessed by asking, “How often do you drink?” with response options of Rarely, Occasionally, or Everyday.
OutcomesThe primary outcome was MACE defined as AMI (ICD-10 codes: I21.0, I21.1, I21.2, I21.3, I21.4, and I21.9), a hospitalization for unstable angina (ICD-10 code: I20.0), ischemic stroke (ICD-10 codes: I63.0, I63.1, I63.2, I63.3, I63.4, I63.5, I63.6, I63.8, I63.9, I69.3), and cardiac death23, 30). Cardiac death included cardiocerebrovascular- or acute heart failure (ICD-10 codes: I50.0 and I50.9)- related death. If a participant experienced two or more events, the first was counted as the outcome. Secondary outcomes were defined as AMI, ischemic stroke, or all-cause death and were analyzed separately. These outcomes were assessed from the date of the health checkup to August 2020.
Statistical AnalysesCox proportional hazards regression analysis treating TG as a continuous variable was used to compute the hazard ratios (HRs) and 95% confidence intervals (CIs) of clinical outcomes associated with TG levels. In addition, to reveal a potential non-linear relationship between TG levels and clinical outcomes, Cox hazard proportional regression model with natural cubic spline regression was performed with a reference TG level of 150 mg/dL. Interaction analyses were conducted to elucidate the distinct elevated TG level effects on clinical outcomes within the primary and secondary preventive contexts. Multivariable models were adjusted for potential confounding factors such as age, sex, BMI, current smoking status, hypertension, diabetes mellitus, LDL-C level, HDL-C level and statin use. To assess the interaction between primary and secondary prevention cohorts, we combined the datasets of all participants. An interaction term between prevention category (primary vs. secondary) and TG levels was included in the regression models. This combined analysis allowed us to evaluate the differential effects of TG levels on clinical outcomes across the two prevention categories. The interaction results were analyzed using multivariable-adjusted models. The population-attributable fraction (PAF) for clinical outcomes associated with high TG levels were computed. The PAF is a crucial tool in epidemiology to assess the impact of exposure on public health31). It quantifies how reducing risk factors may decrease disease occurrence. The PAF highlights potential health improvements by moving from current exposure to an ideal state. The PAF (%) was calculated using the Miettinen formula, as previously described32). PAF was defined as exposure proportion among cases×(adjusted HR - 1) /adjusted HR×100. Adjusted HR values were derived from multivariable models to account for potential confounders. The PAF for clinical outcomes associated with higher TG levels (≥ 50 mg/dL), compared to the very low TG group (<50 mg/dL), was calculated as the sum of the PAFs for each of the three higher TG categories32). For the sensitivity analysis, an iterative imputer method for missing values was used with 10 iterations of Bayesian Ridge. In primary prevention, subgroup analyses were performed to investigate the influence of TG levels on outcomes using three risk categories (low, intermediate, high risk of atherosclerotic cardiovascular disease) according to the Japan Atherosclerosis Society Guidelines for Prevention of Atherosclerotic Cardiovascular Diseases 2022 22), or statins use. The level of significance was defined as a two-sided p-value of <0.05. All statistical analyses were performed using R software version 4.0.5. (R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/.) and Python (V.3.7.11, Python Software Foundation).
For 15 years, 3,415,522 participants were involved in primary prevention, with a median age of 44 years and 69% were men. Additionally, 29,806 participants engaged in secondary prevention, with a median age of 58 years, and 92% were men. In the secondary prevention group, 76% and 30% had a history of cardiovascular disease and cerebrovascular disease, respectively. A summary of baseline characteristics is presented in Table 1. In the primary prevention group, participants exhibited lower BMI, waist circumference, systolic and diastolic blood pressures, and a lower prevalence of hypertension and diabetes mellitus; however, a higher proportion smoked, compared to those in the secondary prevention group.
|
missing, % |
Overall N= 3,445,328 |
Primary Prevention N= 3,415,522 |
Secondary Prevention N= 29,806 |
p value | |
|---|---|---|---|---|---|
| Age, years | 0 | 45 (36, 53) | 44 (36, 53) | 58 (53, 63) | <0.001 |
| Male, n (%) | 0 | 2,390,026 (69%) | 2,362,627 (69%) | 27,399 (92%) | <0.001 |
| Body mass index, kg/m2 | 0.02 | 22.7 (20.5, 25.3) | 22.7 (20.5, 25.3) | 25.2 (23.1, 27.8) | <0.001 |
| <18.5 | 254,235 (7.4%) | 253,927 (7.4%) | 308 (1.0%) | ||
| ≥ 18.5, <25 | 2,239,375 (65%) | 2,225,800 (65%) | 13,575 (46%) | ||
| ≥ 25, <30 | 757,414 (22%) | 745,409 (22%) | 12,005 (40%) | ||
| ≥ 30 | 193,719 (5.6%) | 189,803 (5.6%) | 3,916 (13%) | ||
| Waist circumference, cm | 3.85 | 81 (75, 88) | 81 (75, 88) | 89 (83, 96) | <0.001 |
| Systolic blood pressure, mmHg | 0.02 | 119 (109, 129) | 119 (109, 129) | 126 (116, 136) | <0.001 |
| Diastolic blood pressure, mmHg | 0.02 | 74 (66, 82) | 74 (66, 82) | 78 (71, 85) | <0.001 |
| Hypertension, n (%) | 0.003 | 344,823 (10%) | 322,934 (9.5%) | 21,889 (73%) | <0.001 |
| Diabetes, n (%) | 0.005 | 108,801 (3.2%) | 101,163 (3.0%) | 7,638 (26%) | <0.001 |
| Current smoking, n (%) | 0.09 | 968,008 (28%) | 962,386 (28%) | 5,622 (19%) | <0.001 |
| Alcohol consumption, n (%) | 1.37 | <0.001 | |||
| Everyday | 850,046 (25%) | 841,859 (25%) | 8,187 (28%) | ||
| Occasionally | 1,291,925 (38%) | 1,282,457 (38%) | 9,468 (32%) | ||
| Rarely | 1,256,145 (37%) | 1,244,263 (37%) | 11,882 (40%) | ||
| History of cerebrovascular disease, n (%) | 0 | 8,817 (0.3%) | 0 (0%) | 8,817 (30%) | <0.001 |
| History of cardiovascular disease, n (%) | 0 | 22,581 (0.7%) | 0 (0%) | 22,581 (76%) | <0.001 |
| Glucose, mg/dL | 3.84 | 92 (86, 99) | 92 (86, 99) | 103 (94, 118) | <0.001 |
| HbA1c, % | 10.55 | 5.40 (5.20, 5.60) | 5.40 (5.20, 5.60) | 5.90 (5.50, 6.40) | <0.001 |
| LDL-C, mg/dL | 0 | 119 (98, 141) | 119 (99, 141) | 99 (83, 118) | <0.001 |
| HDL-C, mg/dL | 0 | 60 (50, 72) | 60 (51, 72) | 53 (45, 63) | <0.001 |
| TG, mg/dL | 0 | 84 (58, 127) | 84 (58, 127) | 111 (80, 160) | <0.001 |
| Hypertriglyceridemia (TG ≥ 150 mg/dL), n (%) | 0 | 609,199 (18%) | 600,575 (18%) | 8,624 (29%) | <0.001 |
| Statins, n (%) | 0 | 237,706 (6.9%) | 212,015 (6%) | 25,691 (86%) | <0.001 |
| Ezetimibe, n (%) | 0 | 26,313 (0.8%) | 22,022 (0.6%) | 4,291 (14%) | <0.001 |
| PCSK9 inhibitor, n (%) | 0 | 175 (<0.1%) | 51 (<0.1%) | 124 (0.4%) | <0.001 |
| Fibrate, n (%) | 0 | 47,270 (1.4%) | 44,468 (1.3%) | 2,802 (9.4%) | <0.001 |
| Omega-3 carboxylic acids, n (%) | 0 | 9,049 (0.3%) | 8,191 (0.2%) | 858 (2.9%) | <0.001 |
| EPA, n (%) | 0 | 16,323 (0.5%) | 13,944 (0.4%) | 2,379 (8.0%) | <0.001 |
TG, triglyceride; HbA1c, hemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; PCSK9, proprotein convertase subtilisin/kexin type9; EPA, eicosapentaenoic acid.
During a mean follow-up of 3.25±2.53 years, 11,672 first MACE, 4,320 AMI, 2,612 unstable angina, 4,626 ischemic stroke, and 5,170 all-cause death occurred (Supplementary Table 1). As shown in Table 2, TG levels as a continuous variable were significantly associated with MACE in both primary and secondary prevention cohorts (HR: 1.008, 95% CI: 1.006–1.010 in the primary prevention cohort, and HR: 1.008, 95% CI: 1.002–1.014 in the secondary prevention cohort). For AMI, TG levels were significantly associated with risk in the primary prevention cohort (HR: 1.007, 95% CI: 1.004–1.009), but not in the secondary prevention cohort (HR: 1.004, 95% CI: 0.994–1.015). For ischemic stroke, TG levels were significantly associated with risk in both the primary (HR: 1.007, 95% CI: 1.004–1.010) and secondary prevention cohorts (HR: 1.018, 95% CI: 1.010–1.026). No significant association was observed between TG levels and all-cause death in either the primary (HR: 1.000, 95% CI: 0.998–1.003) or secondary (HR: 1.008, 95% CI: 0.995–1.022) prevention cohorts. In addition, Table 3 presents the categorical analysis using TG 150 mg/dL as the cutoff point. The results show that in the primary prevention cohort, TG levels ≥ 150 mg/dL were significantly associated with an increased risk of MACE (HR: 1.13, 95% CI: 1.09-1.18), AMI (HR: 1.13, 95% CI: 1.06-1.21), and ischemic stroke (HR: 1.11, 95% CI: 1.03-1.19) compared to TG levels <150 mg/dL. However, in the secondary prevention cohort, no significant association was observed for these outcomes (HR: 1.08, 95% CI: 0.92-1.26 for MACE; HR: 1.11, 95% CI: 0.83-1.47 for AMI; HR: 1.23, 95% CI: 0.91-1.66 for ischemic stroke). No significant association was observed between TG levels and all-cause death in either the primary (HR: 1.05, 95% CI: 0.98–1.13) or secondary (HR: 0.97, 95% CI: 0.66–1.43) prevention cohorts (Table 3).
|
Overall N= 3,445,328 |
Primary Prevention N= 3,415,522 |
Secondary Prevention N= 29,806 |
|
|---|---|---|---|
| Major adverse cardiovascular event | 11,672 (0.3%) | 10,906 (0.3%) | 766 (2.6%) |
| Acute myocardial infarction | 4,320 (0.1%) | 4,093 (0.1%) | 227 (0.8%) |
| Unstable angina | 2,612 (<0.1%) | 2,274 (<0.1%) | 338 (1.1%) |
| Ischemic stroke | 4,626 (0.1%) | 4,419 (0.1%) | 207 (0.7%) |
| All-cause death | 5,170 (0.2%) | 5,033 (0.1%) | 137 (0.5%) |
Data are n (%).
|
number of participants, n |
number of event, n (%) |
Multivariable | Iterative imputation | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| HR | 95% CI low | 95% CI high | p value | HR | 95% CI low | 95% CI high | p value | |||
| MACE | ||||||||||
| Total cohort | 3,445,328 | 11,672 (0.3%) | 1.008 | 1.006 | 1.010 | <0.001 | 1.008 | 1.006 | 1.010 | <0.001 |
| Primary prevention | 3,415,522 | 10,906 (0.3%) | 1.008 | 1.006 | 1.010 | <0.001 | 1.008 | 1.006 | 1.010 | <0.001 |
| Secondary prevention | 29,806 | 766 (2.6%) | 1.008 | 1.002 | 1.014 | 0.005 | 1.008 | 1.002 | 1.014 | 0.005 |
| AMI | ||||||||||
| Total cohort | 3,445,328 | 4,320 (0.1%) | 1.006 | 1.004 | 1.009 | <0.001 | 1.007 | 1.004 | 1.009 | <0.001 |
| Primary prevention | 3,415,522 | 4,093 (0.1%) | 1.007 | 1.004 | 1.009 | <0.001 | 1.007 | 1.004 | 1.009 | <0.001 |
| Secondary prevention | 29,806 | 227 (0.8%) | 1.004 | 0.994 | 1.015 | 0.405 | 1.004 | 0.994 | 1.015 | 0.402 |
| Ischemic stroke | ||||||||||
| Total cohort | 3,445,328 | 4,626 (0.1%) | 1.008 | 1.005 | 1.010 | <0.001 | 1.008 | 1.005 | 1.010 | <0.001 |
| Primary prevention | 3,415,522 | 4,419 (0.1%) | 1.007 | 1.004 | 1.010 | <0.001 | 1.007 | 1.004 | 1.010 | <0.001 |
| Secondary prevention | 29,806 | 207 (0.7%) | 1.018 | 1.010 | 1.026 | <0.001 | 1.018 | 1.010 | 1.026 | <0.001 |
| All-cause death | ||||||||||
| Total cohort | 3,445,328 | 5,170 (0.2%) | 1.001 | 0.998 | 1.003 | 0.639 | 1.001 | 0.998 | 1.003 | 0.645 |
| Primary prevention | 3,415,522 | 5,033 (0.1%) | 1.000 | 0.998 | 1.003 | 0.801 | 1.000 | 0.998 | 1.003 | 0.807 |
| Secondary prevention | 29,806 | 137 (0.5%) | 1.008 | 0.995 | 1.022 | 0.208 | 1.008 | 0.995 | 1.022 | 0.207 |
HR was adjusted for age, sex, body mass index, smoking habit, hypertension, diabetes mellitus, LDL-C level, HDL-C level and statin use. HR, hazard ratio; MACE, major adverse cardiac events; AMI, acute myocardial infarction.
| Primary Prevention | Secondary Prevention | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
Number of participants |
Number of event |
Incidence rate (95% CI) (per 100,000 person-year) |
HR (95% CI) | PAF (%) |
Number of participants |
Number of event |
Incidence rate (95% CI) (per 100,000 person-year) |
HR (95% CI) | PAF (%) | |
| MACE | ||||||||||
| TG <150 mg/dL | 2,814,947 | 7,136 | 79.1 (78.5, 79.7) | Ref | Ref | 21,182 | 492 | 814 (794, 835) | Ref | Ref |
| TG ≥ 150 mg/dL | 600,575 | 3,770 | 181.7 (179.7, 183.7) | 1.13 (1.09, 1.18) | 4.1 | 8,624 | 274 | 1062 (1025, 1100) | 1.08 (0.92, 1.26) | NA |
| AMI | ||||||||||
| TG <150 mg/dL | 2,814,947 | 2,439 | 27.0 (26.7, 27.3) | Ref | Ref | 21,182 | 138 | 225 (214, 236) | Ref | Ref |
| TG ≥ 150 mg/dL | 600,575 | 1,654 | 79.5 (78.2, 80.9) | 1.13 (1.06, 1.21) | 4.8 | 8,624 | 89 | 339 (318, 361) | 1.11 (0.83, 1.47) | NA |
| Ischemic stroke | ||||||||||
| TG <150 mg/dL | 2,814,947 | 3,099 | 34.3 (33.9, 34.7) | Ref | Ref | 21,182 | 130 | 212 (201, 223) | Ref | Ref |
| TG ≥ 150 mg/dL | 600,575 | 1,320 | 63.4 (62.2, 64.6) | 1.11 (1.03, 1.19) | 2.9 | 8,624 | 77 | 293 (273, 313) | 1.23 (0.91, 1.66) | NA |
| All-cause death | ||||||||||
| TG <150 mg/dL | 2,814,947 | 3,758 | 41.6 (41.2, 42.0) | Ref | Ref | 21,182 | 95 | 154 (145, 163) | Ref | Ref |
| TG ≥ 150 mg/dL | 600,575 | 1,275 | 61.2 (60.0, 62.4) | 1.05 (0.98, 1.13) | NA | 8,624 | 42 | 159 (144, 174) | 0.97 (0.66, 1.43) | NA |
HR was adjusted for age, sex, body mass index, smoking habit, hypertension, diabetes mellitus, LDL-C level, HDL-C level and statin use.
HR, hazard ratio; PAF, population-attributable fraction; MACE, major adverse cardiac events; AMI, acute myocardial infarction; TG, triglyceride.
As shown in Fig.1, the multivariable Cox hazard proportional regression model with natural cubic spline regression revealed that the association of lower TG levels with a lower risk of MACE was more evident in the primary prevention than in the secondary prevention group within the range of less than 150mg/dL (p for interaction; 0.049). Regarding ischemic stroke incidence, the association of lower TG levels with a lower risk of ischemic stroke was more evident in the secondary prevention than in the primary prevention group within the range of more than 150mg/dL (p for interaction; 0.030).

Line graphs reveal the spline curves of adjusted hazard ratios (solid lines) and 95% confidence intervals (translucent areas) for (a) MACE, (b) AMI, (c) stroke, and (d) all-cause death in primary (blue) and secondary (red) prevention. Hazard ratios were adjusted for age, sex, body mass index, smoking habit, hypertension, diabetes mellitus, LDL-C level, HDL-C level, and statin use.
TG, triglyceride; MACE, major adverse cardiovascular event; AMI, acute myocardial infarction, LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol.
The estimated incidence rates of clinical outcomes and PAF of clinical outcomes associated with hypertriglyceridemia are presented in Table 3. In primary prevention, the PAFs were 4.1% for MACE, 4.8% for AMI, and 2.9% for ischemic stroke. In the secondary prevention cohort, however, the adjusted HRs for TG levels ≥ 150 mg/dL were not statistically significant, and thus the PAFs were not presented due to the absence of a meaningful association (Table 3).
Exploring Clinical Outcome Risks in Primary Prevention beyond the TG Level ThresholdThe characteristics and clinical outcomes in primary prevention are summarized according to four TG categories in Supplementary Tables 2-3. The Kaplan–Meier curve provided an estimate of the cumulative incidence of clinical outcomes within these four TG category groups (Supplementary Fig.2). Additionally, Fig.2 indicates the association between the four TG categories and the risk of clinical outcomes in primary and secondary prevention groups. In the primary prevention group, the multivariable Cox hazard proportion regression model indicated that both high normal TG group and hypertriglyceridemia were associated with a higher risk of AMI compared with the very low TG group (HR: 1.24, 95% CI: 1.01–1.54 for the high normal TG group, HR: 1.36, 95% CI: 1.10-1.69 for hypertriglyceridemia). Regarding MACE and ischemic stroke, hypertriglyceridemia was associated with higher risk compared with the very low TG group (HR: 1.15, 95% CI: 1.04–1.28 for MACE, HR: 1.20, 95% CI: 1.04-1.40 for ischemic stroke). However, these association were not significant in the secondary prevention. The findings of the iterative imputation analysis, which served as a sensitivity analysis, were consistent with the main results (Fig.2). In the primary prevention group, the PAFs for MACE, AMI, and ischemic stroke associated with TG levels ≥ 50 mg/dL, compared to the very low TG group (<50 mg/dL), were 5.48%, 20.4%, and 10.5%, respectively (Supplementary Table 4). In the secondary prevention cohort, however, the adjusted HRs for TG levels ≥ 50 mg/dL were not statistically significant, and thus the PAFs were not calculated due to the absence of a meaningful association (Supplementary Table 4).
| Missing, n (%) |
Overall N=3,415,522 |
Very low (<50 mg/dL) N=545,535 |
Low Normal (50 to 99 mg/dL) N=1,553,942 |
High Normal (100 to 149 mg/dL) N=715,470 |
Hypertriglyceridemia (≥ 150 mg/dL) N=600,575 |
p-value | |
|---|---|---|---|---|---|---|---|
| Age, years | 0 (0%) | 44 (36, 53) | 39 (29, 47) | 44 (35, 52) | 47 (40, 55) | 47 (40, 54) | <0.001 |
| Male, n (%) | 0 (0%) | 2,362,627 (69%) | 240,465 (44%) | 1,003,684 (65%) | 580,348 (81%) | 538,130 (90%) | <0.001 |
| BMI, kg/m2 | 583 (0.02%) | 22.7 (20.5, 25.3) | 20.6 (19.0, 22.4) | 22.1 (20.2, 24.3) | 23.9 (21.9, 26.4) | 25.1 (23.1, 27.7) | <0.001 |
| BMI category, n (%) | 583 (0.02%) | <0.001 | |||||
| <18.5 | 253,927 (7.4%) | 94,257 (17%) | 134,558 (8.7%) | 18,893 (2.6%) | 6,219 (1.0%) | ||
| ≥ 18.5, <25 | 2,225,800 (65%) | 409,169 (75%) | 1,112,068 (72%) | 424,860 (59%) | 279,703 (47%) | ||
| ≥ 25, <30 | 745,409 (22%) | 37,387 (6.9%) | 254,588 (16%) | 213,376 (30%) | 240,058 (40%) | ||
| ≥ 30 | 189,803 (5.6%) | 4,640 (0.9%) | 52,494 (3.4%) | 58,204 (8.1%) | 74,465 (12%) | ||
| Waist circumference, cm | 132,458 (3.9%) | 81 (75, 88) | 74 (69, 79) | 79 (73, 86) | 85 (79, 91) | 88 (83, 94) | <0.001 |
| SBP, mmHg | 601 (0.02%) | 119 (109, 129) | 112 (102, 122) | 117 (107, 127) | 122 (112, 132) | 126 (116, 136) | <0.001 |
| DBP, mmHg | 601 (0.02%) | 74 (66, 82) | 68 (61, 75) | 72 (65, 80) | 77 (69, 84) | 80 (72, 87) | <0.001 |
| Hypertension, n (%) | 106 (<0.01%) | 322,934 (9.5%) | 14,951 (2.7%) | 114,526 (7.4%) | 94,118 (13%) | 99,339 (17%) | <0.001 |
| Diabetes, n (%) | 135 (<0.01%) | 101,163 (3.0%) | 5,367 (1.0%) | 34,569 (2.2%) | 28,727 (4.0%) | 32,500 (5.4%) | <0.001 |
| Cigarette smoking, n (%) | 3,145 (0.1%) | 962,386 (28%) | 96,238 (18%) | 396,624 (26%) | 231,317 (32%) | 238,207 (40%) | <0.001 |
| Alcohol consumption, n (%) | 46,943 (1.4%) | <0.001 | |||||
| Daily | 841,859 (25%) | 91,058 (17%) | 361,431 (24%) | 195,303 (28%) | 194,067 (33%) | ||
| Sometimes | 1,282,457 (38%) | 213,951 (40%) | 588,847 (38%) | 264,246 (37%) | 215,413 (36%) | ||
| None | 1,244,263 (37%) | 234,053 (43%) | 582,703 (38%) | 245,405 (35%) | 182,102 (31%) | ||
| Glucose, mg/dL | 131,318 (3.8%) | 92 (86, 99) | 88 (83, 93) | 91 (86, 98) | 94 (88, 102) | 97 (90, 106) | <0.001 |
| HbA1c, % | 360,965 (11%) | 5.40 (5.20, 5.60) | 5.30 (5.10, 5.50) | 5.40 (5.20, 5.60) | 5.50 (5.20, 5.70) | 5.50 (5.30, 5.80) | <0.001 |
| LDL-C, mg/dL | 0 (0%) | 119 (99, 141) | 99 (84, 116) | 116 (98, 136) | 131 (111, 152) | 133 (111, 155) | <0.001 |
| HDL-C, mg/dL | 0 (0%) | 60 (51, 72) | 72 (62, 82) | 64 (55, 75) | 55 (48, 64) | 48 (42, 56) | <0.001 |
| TG, mg/dL | 0 (0%) | 84 (58, 127) | 41 (36, 46) | 71 (60, 84) | 119 (109, 132) | 199 (169, 256) | <0.001 |
| Statins, n (%) | 0 (0%) | 212,015 (6%) | 8,095 (1.5%) | 74,944 (4.8%) | 65,460 (9.2%) | 63,516 (11%) | <0.001 |
| Ezetimibe, n (%) | 0 (0%) | 22,022 (0.6%) | 633 (0.1%) | 6,362 (0.4%) | 6,371 (0.9%) | 8,656 (1.4%) | <0.001 |
| PCSK9 inhibitor, n (%) | 0 (0%) | 51 (<0.1%) | 3 (<0.1%) | 19 (<0.1%) | 16 (<0.1%) | 13 (<0.1%) | 0.037 |
| Fibrate, n (%) | 0 (0%) | 44,468 (1.3%) | 590 (0.1%) | 8,507 (0.5%) | 11,757 (1.6%) | 23,614 (3.9%) | <0.001 |
| Omega-3 carboxylic acids, n (%) | 0 (0%) | 8,191 (0.2%) | 242 (<0.1%) | 1,822 (0.1%) | 2,090 (0.3%) | 4,037 (0.7%) | <0.001 |
| EPA, n (%) | 0 (0%) | 13,944 (0.4%) | 613 (0.1%) | 3,899 (0.3%) | 3,451 (0.5%) | 5,981 (1.0%) | <0.001 |
Data are n (%) or median (IQR).
BMI indicates Body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; TG, triglyceride, PCSK9, proprotein convertase subtilisin/kexin type9; EPA, eicosapentaenoic acid.
|
Overall N=3,415,522 |
Very low (<50 mg/dL) N=545,535 |
Low Normal (50 to 99 mg/dL) N=1,553,942 |
High Normal (100 to 149 mg/dL) N=715,470 |
Hypertriglyceridemia (≥ 150 mg/dL) N=600,575 |
|
|---|---|---|---|---|---|
| Major adverse cardiovascular event | 10,906 (0.3%) | 469 (<0.1%) | 3,591 (0.2%) | 3,076 (0.4%) | 3,770 (0.6%) |
| Acute myocardial infarction | 4,093 (0.1%) | 98 (<0.1%) | 1,137 (<0.1%) | 1,204 (0.2%) | 1,654 (0.3%) |
| Unstable angina | 2,274 (<0.1%) | 90 (<0.1%) | 708 (<0.1%) | 669 (<0.1%) | 807 (0.1%) |
| Ischemic stroke | 4,419 (0.1%) | 250 (<0.1%) | 1,666 (0.1%) | 1,183 (0.2%) | 1,320 (0.2%) |
| All-cause death | 5,033 (0.1%) | 407 (<0.1%) | 2,096 (0.1%) | 1,255 (0.2%) | 1,275 (0.2%) |
Data are n (%).

Line graphs show the incidence rates of (a) MACE, (b) AMI, (c) stroke, and (d) all-cause death in primary prevention according to the four TG category groups.
TG indicates triglyceride, MACE; major adverse cardiovascular event; AMI, acute myocardial infarction.

In the multivariable model, hazard ratios (HRs) were adjusted for age, sex, body mass index, smoking habits, hypertension, diabetes mellitus, LDL-C level, HDL-C level, and statin use. An iterative imputer method for missing values is performed with 10 iterations of Bayesian Ridge.
HR indicates hazard ratio. Other abbreviations are listed in Fig. 1.
| Primary Prevention | Secondary Prevention | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
No. of participants |
No. of event |
Incidence rate (95% CI) (per 100,000 person-year) |
HR (95% CI) | PAF (%) |
No. of participants |
No. of event |
Incidence rate (95% CI) (per 100,000 person-year) |
HR (95% CI) | PAF (%) | |
| MACE | ||||||||||
| Very Low (<50 mg/dL) | 545,535 | 469 | 29.2 (28.4, 29.9) | Ref | Ref | 1,300 | 23 | 672.1 (599.8, 744.4) | Ref | NA |
| Low Normal (50 to 99) | 1,553,942 | 3,591 | 71.8 (71.1, 72.6) | 1.01 (0.91, 1.11) | 5.48 | 11,092 | 244 | 784.9 (757.3, 812.6) | 0.89 (0.58, 1.37) | |
| High Normal (100 to 149) | 715,470 | 3,076 | 127.5 (126.0, 129.0) | 1.03 (0.93, 1.14) | 8,790 | 225 | 868.1 (834.6, 901.5) | 0.84 (0.54, 1.31) | ||
| Hypertriglyceridemia (≥ 150) | 600,575 | 3,770 | 181.7 (179.7, 183.7) | 1.15 (1.04, 1.28) | 8,624 | 274 | 1062.4 (1024.8, 1100.0) | 0.93 (0.60, 1.46) | ||
| AMI | ||||||||||
| Very Low (<50 mg/dL) | 545,535 | 98 | 6.1 (5.7, 6.4) | Ref | Ref | 1,300 | 7 | 201.1 (161.2, 241.0) | Ref | NA |
| Low Normal (50 to 99) | 1,553,942 | 1137 | 22.7 (22.3, 23.1) | 1.16 (0.94, 1.43) | 20.4 | 11,092 | 60 | 190.3 (176.6, 204.0) | 0.65 (0.29, 1.43) | |
| High Normal (100 to 149) | 715,470 | 1,204 | 49.8 (48.9, 50.8) | 1.24 (1.01, 1.54) | 8,790 | 71 | 269.9 (251.1, 288.7) | 0.73 (0.33, 1.62) | ||
| Hypertriglyceridemia (≥ 150) | 600,575 | 1,654 | 79.5 (78.2, 80.9) | 1.36 (1.10, 1.69) | 8,624 | 89 | 339.3 (317.8, 360.7) | 0.77 (0.34, 1.73) | ||
| Ischemic stroke | ||||||||||
| Very Low (<50 mg/dL) | 545,535 | 250 | 15.5 (15.0, 16.1) | Ref | Ref | 1,300 | 3 | 86.4 (60.3, 112.6) | Ref | NA |
| Low Normal (50 to 99) | 1,553,942 | 1,666 | 33.3 (32.8, 33.8) | 1.10 (0.96, 1.27) | 10.5 | 11,092 | 67 | 212.4 (198.0, 226.9) | 2.05 (0.64, 6.55) | |
| High Normal (100 to 149) | 715,470 | 1,183 | 48.9 (48.0, 49.9) | 1.08 (0.93, 1.25) | 8,790 | 60 | 228.1 (210.8, 245.4) | 2.01 (0.62, 6.53) | ||
| Hypertriglyceridemia (≥ 150) | 600,575 | 1,320 | 63.4 (62.2, 64.6) | 1.20 (1.04, 1.40) | 8,624 | 77 | 293.4 (273.5, 313.3) | 2.46 (0.75, 8.04) | ||
| All-cause death | ||||||||||
| Very Low (<50 mg/dL) | 545,535 | 407 | 25.3 (24.6, 26.0) | Ref | Ref | 1,300 | 5 | 143.4 (109.7, 177.1) | Ref | NA |
| Low Normal (50 to 99) | 1,553,942 | 2,096 | 41.8 (41.3, 42.4) | 1.06 (0.95, 1.18) | NA | 11,092 | 47 | 148.4 (136.3, 160.5) | 0.89 (0.35, 2.28) | |
| High Normal (100 to 149) | 715,470 | 1,255 | 51.9 (50.9, 52.8) | 1.04 (0.92, 1.17) | 8,790 | 43 | 162.8 (148.2, 177.4) | 0.92 (0.35, 2.40) | ||
| Hypertriglyceridemia (≥ 150) | 600,575 | 1,275 | 61.2 (60.0, 62.4) | 1.10 (0.97, 1.25) | 8,624 | 42 | 159.1 (144.4, 173.9) | 0.88 (0.33, 2.37) | ||
HR was adjusted for age, sex, body mass index, smoking habit, hypertension, diabetes mellitus, LDL-C level, HDL-C level and statin use.
CI indicates confidence interval; ARD, absolute risk difference; HR, hazard ratio; PAF, population attributable fraction; MACE, major adverse cardiovascular event; AMI, acute myocardial infarction.
A subgroup analysis was conducted to assess whether the association of the TG category with clinical outcomes varied based on the current guideline risk category in primary prevention. The baseline characteristics divided by the risk category are summarized in Supplementary Table 5. As shown in Fig.3, the association between higher TG levels and higher risk of MACE and AMI within the range of more than 50mg/dL, compared with the very low TG group, was consistent among risk categories. The association between higher TG levels and higher risk of ischemic stroke within the range of more than 50mg/dL, compared with the very low TG group, was consistent in the low-risk and high-risk groups, however, that association was not observed in the intermediate risk group. In addition, the association between higher TG levels and higher risk of all-cause mortality was not observed among the risk categories (Fig.3). Interaction was observed between low-risk group and high-risk group in MACE, AMI, and ischemic stroke (p for interaction; <0.001, <0.001, and 0.002, respectively). Consistently, interaction was observed between low-risk group and intermediate-risk group in MACE, AMI, and ischemic stroke (p for interaction; <0.001, <0.001, and <0.001, respectively).
|
Missing value, % |
Overall, N= 3,415,522 |
High risk, N= 164,036 |
Intermediate risk, N= 957,626 |
Low risk, N= 2,293,860 |
p-value | |
|---|---|---|---|---|---|---|
| Age, years | 0% | 44 (36, 53) | 60 (53, 65) | 54 (50, 59) | 40 (32, 46) | <0.001 |
| Male, n (%) | 0% | 2,362,627 (69%) | 150,733 (92%) | 904,947 (94%) | 1,306,947 (57%) | <0.001 |
| BMI, kg/m2 | <0.1% | 22.7 (20.5, 25.3) | 25.0 (22.8, 27.9) | 24.0 (22.0, 26.4) | 22.0 (20.0, 24.4) | <0.001 |
| SBP, mmHg | <0.1% | 119 (109, 129) | 132 (121, 143) | 128 (118, 138) | 115 (106, 124) | <0.001 |
| DBP, mmHg | <0.1% | 74 (66, 82) | 81 (74, 88) | 81 (73, 88) | 70 (64, 78) | <0.001 |
| Hypertension, n (%) | <0.1% | 322,934 (9.5%) | 68,522 (42%) | 179,561 (19%) | 74,851 (3.3%) | <0.001 |
| Diabetes, n (%) | <0.1% | 101,163 (3.0%) | 101,163 (62%) | 0 (0%) | 0 (0%) | <0.001 |
| Current smoking, n (%) | <0.1% | 962,386 (28%) | 64,566 (39%) | 382,530 (40%) | 515,290 (22%) | <0.001 |
| Alcohol consumption, n (%) | 1.4% | <0.001 | ||||
| Everyday | 841,859 (25%) | 52,897 (33%) | 348,675 (37%) | 440,287 (19%) | ||
| Occasionally | 1,282,457 (38%) | 49,336 (31%) | 314,951 (33%) | 918,170 (41%) | ||
| Rarely | 1,244,263 (37%) | 59,517 (37%) | 280,071 (30%) | 904,675 (40%) | ||
| Glucose, mg/dL | 3.8% | 92 (86, 99) | 119 (101, 143) | 97 (90, 105) | 90 (84, 96) | <0.001 |
| HbA1c, % | 10.6% | 5.40 (5.20, 5.60) | 6.50 (5.80, 7.30) | 5.50 (5.30, 5.80) | 5.30 (5.10, 5.50) | <0.001 |
| LDL-C, mg/dL | 0% | 119 (99, 141) | 124 (102, 147) | 133 (112, 155) | 113 (95, 133) | <0.001 |
| HDL-C, mg/dL | 0% | 60 (51, 72) | 53 (45, 63) | 56 (47, 67) | 63 (53, 74) | <0.001 |
| TG, mg/dL | 0% | 84 (58, 127) | 117 (82, 169) | 110 (77, 161) | 73 (52, 107) | <0.001 |
| Statin therapy, n (%) | 0% | 212,015 (6.2%) | 49,785 (30%) | 99,641 (10%) | 62,589 (2.7%) | <0.001 |
| Regular | 23,477 (0.7%) | 5,651 (3.4%) | 11,492 (1.2%) | 6,334 (0.3%) | ||
| High intensity | 188,538 (5.5%) | 44,134 (27%) | 88,149 (9.2%) | 56,255 (2.5%) | ||
| Ezetimibe, n (%) | 0% | 22,022 (0.6%) | 5,612 (3.4%) | 10,148 (1.1%) | 6,262 (0.3%) | <0.001 |
| PCSK9 inhibitor, n (%) | 0% | 51 (<0.1%) | 5 (<0.1%) | 21 (<0.1%) | 25 (<0.1%) | n/a |
| Fibrate, n (%) | 0% | 44,468 (1.3%) | 12,440 (7.6%) | 21,592 (2.3%) | 10,436 (0.5%) | <0.001 |
| Omega-3 carboxylic acids, n (%) | 0% | 8,191 (0.2%) | 1,778 (1.1%) | 3,984 (0.4%) | 2,429 (0.1%) | <0.001 |
| EPA, n (%) | 0% | 13,944 (0.4%) | 3,288 (2.0%) | 6,800 (0.7%) | 3,856 (0.2%) | <0.001 |
Data are n (%) or median (IQR).
BMI indicates Body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; TG, triglyceride, PCSK9, proprotein convertase subtilisin/kexin type9; EPA, eicosapentaenoic acid.

Risk category was based on the Japan Atherosclerosis Society Guidelines for Prevention of Atherosclerotic Cardiovascular Diseases 2022. Prediction model for the onset of atherosclerotic cardiovascular disease using the Hisayama score including the factors such as age, sex, systolic blood pressure, prediabetes, LDL-C, HDL-C, and smoking status, was employed. Hazard ratios were adjusted for statin use. Abbreviations are listed in Figs. 1 and 2.
Another subgroup analysis stratified by the use of statins was performed. The baseline characteristics divided by the use of statins are summarized in Supplementary Table 6. As shown in Supplementary Fig.3, compared with the very low TG group, hypertriglyceridemia was associated with a higher risk of MACE, AMI, and ischemic stroke, and the high normal TG group was associated with a higher risk of AMI in the no use of statins group. However, in the statin use group, higher TG levels were not associated with higher risk of clinical outcomes. Interaction was observed between statins use and no use of statins in MACE, AMI, and ischemic stroke incidence (p for interaction; <0.001, <0.001, and <0.001, respectively).
|
Missing value, % |
Overall, N= 3,415,522 |
No statin, N= 3,203,507 |
Statin, N= 212,015 |
p-value | |
|---|---|---|---|---|---|
| Age, years | 0% | 44 (36, 53) | 44 (35, 52) | 55 (49, 61) | <0.001 |
| Male, n (%) | 0% | 2,362,627 (69%) | 2,194,342 (68%) | 168,285 (79%) | <0.001 |
| BMI, kg/m2 | <0.1% | 22.7 (20.5, 25.3) | 22.6 (20.4, 25.1) | 24.9 (22.7, 27.6) | <0.001 |
| SBP, mmHg | <0.1% | 119 (109, 129) | 119 (108, 129) | 126 (116, 136) | <0.001 |
| DBP, mmHg | <0.1% | 74 (66, 82) | 73 (66, 82) | 79 (72, 86) | <0.001 |
| Hypertension, n (%) | <0.1% | 322,934 (9.5%) | 234,164 (7.3%) | 88,770 (42%) | <0.001 |
| Diabetes, n (%) | <0.1% | 101,163 (3.0%) | 60,582 (1.9%) | 40,581 (19%) | <0.001 |
| Current smoking, n (%) | <0.1% | 962,386 (28%) | 908,947 (28%) | 53,439 (25%) | <0.001 |
| Alcohol consumption, n (%) | 1.4% | <0.001 | |||
| Everyday | 841,859 (25%) | 789,157 (25%) | 52,702 (25%) | ||
| Occasionally | 1,282,457 (38%) | 1,210,491 (38%) | 71,966 (34%) | ||
| Rarely | 1,244,263 (37%) | 1,160,111 (37%) | 84,152 (40%) | ||
| Glucose, mg/dL | 3.8% | 92 (86, 99) | 92 (86, 99) | 100 (92, 114) | <0.001 |
| HbA1c, % | 10.6% | 5.40 (5.20, 5.60) | 5.40 (5.20, 5.60) | 5.80 (5.50, 6.20) | <0.001 |
| LDL-C, mg/dL | 0% | 119 (99, 141) | 119 (99, 141) | 116 (98, 138) | <0.001 |
| HDL-C, mg/dL | 0% | 60 (51, 72) | 61 (51, 72) | 56 (48, 66) | <0.001 |
| TG, mg/dL | 0% | 84 (58, 127) | 82 (57, 124) | 114 (82, 162) | <0.001 |
| Statin therapy, n (%) | 0% | 212,015 (6.2%) | 0 (0%) | 212,015 (100%) | <0.001 |
| regular | 23,477 (0.7%) | 0 (0%) | 23,477 (11%) | ||
| strong | 188,538 (5.5%) | 0 (0%) | 188,538 (89%) | ||
| Ezetimibe, n (%) | 0% | 22,022 (0.6%) | 9,886 (0.3%) | 12,136 (5.7%) | <0.001 |
| PCSK9 inhibitor, n (%) | 0% | 51 (<0.1%) | 7 (<0.1%) | 44 (<0.1%) | <0.001 |
| Fibrate, n (%) | 0% | 44,468 (1.3%) | 33,072 (1.0%) | 11,396 (5.4%) | <0.001 |
| Omega-3 carboxylic acids, n (%) | 0% | 8,191 (0.2%) | 4,317 (0.1%) | 3,874 (1.8%) | <0.001 |
| EPA, n (%) | 0% | 13,944 (0.4%) | 7,424 (0.2%) | 6,520 (3.1%) | <0.001 |
Data are n (%) or median (IQR).
BMI indicates Body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; HbA1c, hemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; TG, triglyceride, PCSK9, proprotein convertase subtilisin/kexin type9; EPA, eicosapentaenoic acid.

The hazard ratios (HRs) were adjusted for age, sex, body mass index, smoking habits, hypertension, diabetes mellitus, LDL-C level, and HDL-C level. Abbreviations are listed in Supplementary Figures 1 and 2.
Our analysis of a nationwide claims database yielded several key findings: 1) hypertriglyceridemia (TG ≥ 150 mg/dL) was associated with high risk of atherosclerotic cardiovascular events in the primary prevention cohort, but such association was not observed in the secondary prevention cohort. 2) Within a specific range of TG levels, an interaction was confirmed between categories of prevention and the association of TG levels with MACE (TG <150 mg/dL) and ischemic stroke (TG ≥ 150 mg/dL). 3) The PAFs of hypertriglyceridemia in primary prevention were significant, but in secondary prevention, due to non-significant hazard ratios, PAFs were not reported. 4) Adjusted for LDL-C, HDL-C, and statin use, lower risks of AMI were observed in the lower TG category than in the current threshold (i.e., 150 mg/dL at fasting) in primary prevention, but not in secondary prevention. 5) In participants with the high-risk group for primary prevention and undergoing statin therapy, higher TG levels were associated with a non-significant or modest increase in the risk of MACE. Conversely, in participants with low-risk and not receiving statin therapy, higher TG levels were associated with a significantly elevated risk of MACE. These findings highlight the need for tailored TG control strategies based on the prevention and risk category.
Previous studies indicate that elevated TG levels increase the risk of cardiovascular and cerebrovascular diseases, not only in Western countries but also in Asian regions11, 13, 15, 33-38). The SUITA study was a 15.1-year prospective cohort study involving 6,684 Japanese participants aged 30 to 79 years without a history of cardiovascular disease. It found that fasting triglyceride levels were an independent predictor of ischemic cardiovascular disease risk, even after adjusting for LDL-C levels. The association was more evident in individuals with LDL-C below 140 mg/dL15). The CIRCS study, which involved 10,851 non-fasting and 4,057 fasting samples from Japanese residents aged 40 to 69 years, identified optimal cut-off points for triglyceride levels to predict ischemic heart disease. These were 145 mg/dL for non-fasting TG and 110 mg/dL for fasting TG, both lower than the recommended cut-off points in the US and Europe38). In alignment with these epidemiological studies, our study results revealed that elevated TG levels were significantly associated with an increased risk of atherosclerotic diseases, such as MACE, AMI, and ischemic stroke in primary prevention cohort (Fig.1, Table 3). Consequently, these segments may be potential candidates for cardioprotective interventions and pharmacotherapies against the high risk of atherosclerotic events. LDL-C-lowering therapy is well–established for the prevention of cardiovascular events. For secondary prevention, a combination of high-dose statins with agents such as ezetimibe and PCSK9 inhibitors is recommended4-8, 19, 39). Conversely, the effectiveness of pharmacotherapeutic interventions targeting TGs remains controversial. The JELIS study, a RCT involving 18,645 hypercholesterolemic patients, assessed the effects of EPA on MACE. Over a mean follow-up of 4.6 years, the EPA treatment group had a 19% relative reduction in the risk of MACE in Japanese primary and secondary prevention cohorts17). Another multicenter, randomized, double-blind, placebo-controlled trial (REDUCE-IT trial) with 8,179 patients with elevated TG levels (70.7% for secondary prevention of cardiovascular events) investigated the effects of icosapent ethyl on ischemic events, resulting in a median follow-up of 4.9 years. Icosapent ethyl reduced the risk of the primary composite endpoint of cardiovascular events with an HR of 0.75 (95% CI, 0.68–0.83)18). However, in a multinational double-blind RCT (PROMINENT trial) involving 10,497 patients with type 2 diabetes and mild to moderate hypertriglyceridemia (66.9% with previous cardiovascular disease), the effects of pemafibrate were neutral16). After a median follow-up of 3.4 years, pemafibrate significantly reduced TGs by 26.2%, however, it did not significantly reduce the primary composite endpoint of cardiovascular events with an HR of 1.03 (95% CI, 0.91–1.15)16).
The variations in the outcomes of these RCTs may stem largely from the different drugs employed in the interventions. However, the participants enrolled in these RCTs might not have been the most suitable candidates for TG interventions. What are the characteristics of candidates who require TG interventions, or what constitutes the optimal target values for management? Here, the association between TG levels and MACE risk in the secondary prevention cohort was not as strong as that in the primary prevention cohort, as shown in Fig.1 and Table 3. Additionally, hypertriglyceridemia was associated with a non-significant or modest increase in the risk of MACE in patients with the high-risk primary prevention and receiving statins (Fig.3 and Supplementary Fig.3). Conversely, in participants with the low-risk primary prevention and not receiving statin therapy, hypertriglyceridemia was associated with a significantly elevated risk of MACE (Fig.3 and Supplementary Fig.3). Based on these findings, the most suitable candidates for TG interventions are individuals with low-risk for primary prevention and not receiving statin therapy, but not those with high-risk for primary prevention, secondary prevention, or receiving statin therapy. Previous most RCTs comparing TG interventions focused on high-risk for primary prevention or secondary prevention with statin therapy, so the effects of TG interventions might be neutral. Therefore, TG intervention may be particularly beneficial for low-risk participants in primary prevention, though further RCT are needed to confirm its effectiveness.
Previous reports have shown that in patients receiving secondary prevention on statin therapy for LDL-C management, TG levels >200 mg/dL was associated with an increased presence of coronary artery plaques40). Furthermore, the intravascular ultrasound study did not reveal plaque regression effects at TG levels <150 mg/dL40). In this study, the HR for MACE and AMI in secondary prevention remained unchanged even when TG levels were below 150 mg/dL, aligning with prior findings. Although high MACE incidence in the secondary prevention cohort suggests a need for residual risk intervention, our results suggest that the primary prevention cohort might be more suitable for TG interventions. Additionally, in the primary prevention cohort, the PAFs for clinical outcomes associated with TG levels ≥ 50 mg/dL were higher than those associated with TG levels ≥ 150 mg/dL, both compared with their respective very low TG groups (<50 mg/dL and <150 mg/dL, respectively) (Table 3 and Supplementary Table 4). This finding suggests that a stricter management target for TG levels may be warranted to achieve better clinical outcomes. The CIRCS study further supports this, identifying 110 mg/dL as the optimal fasting TG cut-off for predicting ischemic heart disease in a Japanese population, which is lower than Western recommendations38). Although the incidence rate of MACE was lower in the primary prevention cohort, this cohort represents a larger population. Therefore, early intervention with a lower TG target (TG <50 mg/dL) in primary prevention could reduce both disease and economic burdens. Future clinical studies should explore the benefits of targeting lower TG levels in individuals without a history of cardiovascular or cerebrovascular events.
The differential impact of TG levels on the risk of atherosclerotic cardiovascular events between the primary and secondary prevention cohorts warrants further consideration into the underlying pathophysiological mechanisms. It is imperative to consider the pathophysiological processes that may account for this variance in risk potency. While the current study has shed light on the association between TG levels and cardiovascular risk, it also unveils the complexity inherent in cardiovascular disease prevention, where one-size-fits-all approaches may not be adequate. Specifically, the primary prevention group, characterized by the absence of established cardiovascular disease, likely represents a more heterogeneous population in terms of atherosclerotic burden and metabolic profiles. Conversely, the secondary prevention group, already diagnosed with cardiovascular disease, may have a higher baseline risk, thus diminishing the relative contribution of TG as an independent risk factor. Moreover, statin therapy, commonly prescribed for secondary prevention, could modulate the influence of TGs on cardiovascular outcomes. This modulation might be due to the pleiotropic effects of statins, which extend beyond LDL-C lowering to involve anti-inflammatory and plaque-stabilizing actions, potentially overshadowing the impact of TG levels41-43). This is because TGs contribute to atherosclerosis by macrophage uptake of triglyceride-rich lipoprotein remnants, promoting foam cell formation, lipoprotein lipase-mediated hydrolysis releasing oxidized fatty acids, inducing oxidative stress, inflammation, LDL oxidation, leukocyte adhesion, platelet aggregation, and coagulation44). Thus, these mechanisms of TG-induced atherosclerosis formation might be different between those with no prior cardiovascular disease and those with pre-existing conditions who take statins. This difference could contribute to the variations in risk intensity observed in the present study. However, further research is needed to fully understand the underlying mechanisms and confirm these findings.
This study had several limitations. First, its retrospective nature, relying on the JMDC Claims Database, may have introduced a selection bias. The JMDC database primarily consists of data from employer-provided health insurance plans, which over-represent working-age male participants, particularly in the secondary prevention cohort. As a result, there was a significant gender imbalance in our study population, with 92% of the secondary prevention cohort being male. This may limit the generalizability of our findings, particularly to female patients, and caution should be exercised when extrapolating these results to a more balanced gender distribution. Secondly, although we adjusted for numerous confounding factors, unmeasured confounders may have influenced the observed associations. Third, our findings were based mainly on the Japanese population, which may limit their generalizability to other ethnic groups or populations. Fourth, potential underreporting or misclassification of outcomes may have occurred, given the reliance on ICD-10 codes for event identification.
Our findings highlight the importance of managing TG levels, particularly in individuals without a history of cardiovascular or cerebrovascular events. The findings presented here may serve as a clarification call for clinicians, policymakers, and patients, highlighting the need for targeted management of TG levels based on the prevention and risk category.
The study protocol was approved by the Institutional Review Board of Kumamoto University Hospital (Rinri No. 2666) and was conducted in accordance with the principles outlined in the Declaration of Helsinki.
Dr. Ishii received full access to all data in the study and took responsibility for the integrity of the data and the accuracy of the data analysis.
We would like to acknowledge the assistance of ChatGPT-4 for English language editing of this manuscript, and we thank Editage (www.editage.com) for their English language editing services.
This work was supported by a grant for medical research from the Research Institute of Healthcare Data Science. However, it played no role in the design of the trial, collection or analysis of the data, interpretation of the trial results, or the writing of the manuscript.
K.T. received research grants from PPD-Shin Nippon Biomedical Laboratories and Alexion Pharmaceuticals and scholarship funds from Abbott Medical, Bayer, Boehringer Ingelheim, Daiichi Sankyo, ITI, Ono Pharmaceutical, Otsuka Pharmaceutical, and Takeda Pharmaceutical; affiliation with the endowed department from Abbott Medical, Boston Scientific, Cardinal Health, Fides-ONE, Fukuda Denshi, GM Medical, ITI, Japan Lifeline, Kaneka Medix, Medical Appliance, Medtronic, Nipro, and Terumo; and honoraria from Abbott Medical, Amgen, AstraZeneca, Bayer, Daiichi Sankyo, Medtronic, Kowa, Novartis Pharma, Otsuka Pharmaceutical, Pfizer, and Janssen Pharmaceutical. Other authors have no conflicting interests to disclose.