What is the clinical evidence from this study?

Study design: Cohort. Population: Cardiovascular disease (n=7521). Intervention: Triglyceride-Glucose (TyG) index vs. Baseline/lower TyG index. Primary outcome: Incident cardiovascular disease (CVD) (HR 1.16, 95% CI 1.07-1.25, p=<0.001).

September 29, 2020Open Access

The impact of triglyceride-glucose index on incident cardiovascular events during 16 years of follow-up: Tehran Lipid and Glucose Study

Q: What are the key findings of this study?

A 1-SD increase in the triglyceride-glucose index was significantly associated with a 16% higher risk of incident cardiovascular disease (HR 1.16) over a median follow-up of 16.1 years.

Key Result

A 1-SD increase in the triglyceride-glucose index was significantly associated with a 16% higher risk of incident cardiovascular disease (HR 1.16) over a median follow-up of 16.1 years.

Study Design

Type

Cohort (n=7,521)

Multicenter

Structured PICO

Is a higher Triglyceride-Glucose (TyG) index associated with an increased risk of incident cardiovascular disease and coronary heart disease in adults without baseline CVD?

Population

7,521 Iranian adults aged ≥ 30 years (mean age 46.6, 44.8% male) without prevalent cardiovascular disease at baseline, from the community-based Tehran Lipid and Glucose Study.

Intervention

Higher Triglyceride-Glucose (TyG) index, evaluated as a continuous variable (per 1-SD increase) and categorically (quintiles 2-5).

Comparator

Lowest quintile of TyG-index (< 8.4).

Outcome

Incident cardiovascular disease (CVD), defined as a composite of coronary heart disease (CHD) plus fatal and non-fatal stroke, and incident CHD alone, at a median follow-up of 16.1 years.composite

An elevated TyG-index is an independent predictor of incident cardiovascular events over a 16-year follow-up, particularly in younger adults, though it does not improve risk prediction beyond the Framingham Risk Score.

Main Result

Effect estimate: HR 1.16 (95% CI 1.07-1.25)

p-value: p=<0.001

Limitations

Only baseline values of TyG-index and other risk factors were used, without considering changes over the follow-up time.
Findings from the metropolitan city of Tehran may not be generalizable to other populations.
Nutritional habits or energy intake, which might affect triglyceride levels, were not recorded.

Abstract

Abstract Background To investigate whether the Triglyceride-Glucose index (TyG-index) is associated with increased risk of cardiovascular diseases (CVD) /coronary heart disease (CHD). Methods A total of 7521 Iranians aged ≥ 30 years (male = 3367) were included in the study. Multivariate Cox regression analyses (adjusted for age, gender, waist circumference, body mass index, educational level, smoking status, physical activity, family history of CVD, type 2 diabetes, hypertension, low and high density lipoprotein cholesterol, and lipid lowering drugs) were used to assess the risk of incident CVD/CHD across quintiles and for 1-standard deviation (SD) increase in the TyG-index. The cut off point for TyG-index was assessed by the minimum value of ({1 - sensitivity) ^2 + (1 - specificity) ^2 } 1 - s e n s i t i v i t y 2 + 1 - s p e c i f i c i t y 2. We also examined the added value of the TyG-index in addition to the Framingham risk score when predicting CVD. Results During follow-up, 1084 cases of CVD (male = 634) were recorded. We found a significant trend of TyG-index for incident CVD/CHD in multivariate analysis (both Ps for tend ≤ 0. 002). Moreover, a 1-SD increase in TyG-index was associated with significant risk of CVD/CHD in multivariate analysis 1. 16 (1. 07–1. 25) and 1. 19 (1. 10–1. 29), respectively. The cut-off value of TyG-index for incident CVD was 9. 03 (59. 2% sensitivity and 63. 2% specificity) ; the corresponding value of TyG-index for incident CHD was 9. 03 (60. 0% sensitivity and 62. 8% specificity), respectively. Although no interaction was found between gender and TyG-index for CVD/CHD in multivariate analysis (both Ps for interaction > 0. 085), the significant trend of TyG-index was observed only among females for incident CVD (P = 0. 035). A significant interaction was found between age groups (i. e. ≥ 60 vs < 60 years) and TyG-index for CVD outcomes in the multivariate model (P-value for interaction = 0. 046). Accordingly, a significant association between the TyG-index and outcomes was found only among the younger age group. Among the population aged < 60 the addition of TyG-index to the Framingham risk score (FRS) did not show improvement in the predictive ability of the FRS, using integrated discrimination improvement. Conclusion The TyG-index is significantly associated with increased risk of CVD/CHD incidence; this issue was more prominent among the younger population. However, adding TyG-index to FRS does not provide better risk prediction for CVD.

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