Triglyceride to HDL-cholesterol ratio as an important lipid fraction to predict early CAD in normal healthy individuals

 

 

Abstract               Background and objectives: Premature coronary artery disease (CAD) is one of the main disease burden, and cause of death in India. Risk factors are associated with lifestyle and other metabolic factors. Hence the present study aims find a simple, effective marker of early detection of CAD by accessing the level of TG/HDL-Cholesterol level in CAD patients and in normal healthy individuals. Materials methods: This study involved two groups, Group A – includes 100 cases of CAD diagnosed on the basis of coronary angiography. Group B – includes 100 controls who recruited for general health check-up. Biochemical parameters studied were Glucose, Urea, Creatinine, lipid profile, Cholesterol /HDL ratio, HDL/VLDL ratio and TG/HDL ratio. Results: We found that FBS, Urea and Creatinine are statistically significant. HDL (P-value-0.018) is statically significant. HDL/VLDL ratio is statically significant. P-value is 0.018. TG/HDL ratio is significant (P-value-0.007***). Inter Quartile Range (IQR) of TG/HDL shows 2.86 variability in cases compared to cases (IQR- 2.45). Conclusion: The TG/HDL‑C ratio can be used as a strong, independent marker of CAD for the early detection. Key Words: CAD - Coronary artery disease, HDL-high density lipoprotein, sd-LDL- small density LDL.VLDL- Very low density lipoprotein. TG- Triglycerides

 

INTRODUCTION

Coronary artery diseases (CAD) are the main cause of disease burden and deaths globally.¹ An estimated 17.9 million people died from CADs in 2016, representing 31% of all global deaths.² In 2016 cardiovascular diseases contributed 28.1% of the total deaths and 14.1% of the total disability-adjusted life-years (DALYs) in India.¹ The rate of early onset (premature) coronary artery disease (EOCAD) is increasing among Indians ³. The risk factors are strongly associated with four particular behaviors: tobacco smoking, physical inactivity, unhealthy diet and the harmful use of alcohol. These behaviors lead to four key metabolic/physiological changes like raised blood pressure, overweight/obesity, insulin resistance and hyperlipidemia includes high total cholesterol, low HDL and high LDL.⁴ sd‑LDL particles as being most strongly linked to CAD and the most frequent form of dyslipidemia in heart disease. ⁵ Traditional lipid profiles include LDL‑cholesterol (LDL‑C) but do not reflect sd‑LDL and increased sd‑LDL particles are often accompanied by a normal LDL‑C. On the other hand, direct measurement of sd‑LDL is technically not applicable for routine biochemical estimation.⁶ A surrogate marker for sd‑LDL is the TG‑by‑HDL‑C ratio (TG/HDL‑C ratio). (7) The TG/HDL‑C ratio has recently been reported as an independent predictor of insulin resistance as well as evidences suggests that TG/HDL‑C levels have the strongest association with CAD.⁷ The aim of our present study is to, investigates the prevalence of the TG/ HDL‑C ratio as a predictor of CAD among apparently healthy, Indian population and assessed its relationship with other lipid fractions compared to coronary artery disease patients.

 

MATERIALS AND METHODS

The present study conducted from January 2018 to June 2019 in MES medical college and hospital, Malappuram, Kerala, India with the approval of Institute ethical committee. The subjects recruited for the study were categorized into two groups –Group A – includes 100 cases of CAD diagnosed on the basis of coronary angiography. Group B – includes 100 controls who recruited for general health check-up. Patients were excluded with previous history of diabetes, hypertension and patients on antilipidemic drugs. 5ml of fasting blood sample was collected from all subjects using vacutainers. The samples were subsequently centrifuged, aliquoted, and transferred to the laboratory for biochemical analysis. The analytical procedures were done in VITROS-5600, performed on the same day. Serum blood glucose measured by GOD-POD method. Serum urea estimated by VITROS BUN/UREA Slide method. Serum creatinine measured by VITROS CREA Slide method. Serum total cholesterol by VITROS Chemistry Products CHOL Slides method. Serum TG by VITROS TRIG Slides method. HDL-C value measured by VITROS dHDL Slide method. LDL-C estimation was using Friedewald equation. The TG/HDL‑C ratio was calculated with the measured values of serum TG and HDL‑C. TC/HDL‑C ratio was calculated with the measured values of TC and HDL‑C.

STATISTICAL ANALYSIS

Descriptive statistics were computed on variables such as age and gender. Mann-Whitney U test is used for the comparison between cases and control groups. All of the statistical analyses were performed using Statistical Package for Social Sciences (SPSS) version 16.0. P value < 0.05 was considered statistically significant.

RESULT

TABLE 1 Shows comparison of routine laboratory parameters, lipid profile, cholesterol to HDL ratio, HDL to VLDL ratio, TG to HDL ratio between group-A and group-B. FBS, Urea and Creatinine are statistically significant. HDL (P-value-0.018) is statically significant. HDL/VLDL ratio is statically significant. P-value is 0.018. TG/HDL ratio is significant. (P-value-0.007). Inter Quartile Range (IQR) shows 2.86 variability in cases of TG/HDL compared to cases (IQR- 2.45).

 

TABLE: 1 COMPARISON OF CASE AND CONTROL

* P < 0.05 was considered statistically significant.

 DISCUSSION

In this present study we have observed high levels of TG/HDL-C ratio in CVD cases.TG/HDL-C ratio shows a close relationship between lipid parameters, BMI and body fat. Especially it is significantly correlated with sd-LDL.⁸ sd-LDL -C has a greater atherogenic potential than LDL. Circulating sd-LDL undergoes multiple atherogenic modifications in blood such as desialyation, glycation and oxidation. It further intensifies the atherogenic effects. Modified sd-LDL is an independent potent marker of inflammatory processes associated with CAD ⁵. Several laboratory methods have been developed for the estimation of sd-LDL, such as ultracentrifugation, gradient gel-electrophoresis (iodixanol gradient method), nuclear magnetic resonance (NMR), high performance liquid chromatography (HPLC) with gel filtration columns, dynamic light scattering, ion mobility analysis and homogenous assay analysis ^9-15. So, the direct measurement of sd-LDL is technically demanding, resource intensive. As a result these precise and accurate techniques are not applicable in routine clinical biochemistry analysis. So the surrogate marker for sd- LDL is the TG/HDL-C ratio estimation.⁷ Gaziano et al proposed that the ratio of TG/HDL-C is an atherogenic index that has been proven to be a highly significant independent predictor of CVD even stronger than TC/HDL-C and LDL-C/HDL-C.¹⁶ The Copenhagen Male Study showed that triglycerides on their own acting as a strong risk factor, but it is found that triglyceride levels by HDL-c levels led to more accurate detection of increased risk of coronary disease.¹⁷ The atherogenic link between high triglycerides and HDL-c is due to the higher plasma concentration of triglyceride-rich, very low-density lipoprotein that generates small, dense LDL during lipid exchange and lipolysis. These LDL particles accumulate in the circulation and form small, dense HDL particles, which undergo accelerated catabolism, this is how atherogenic circle produce its awful effects on cardiac system.^18,19 Hadaegh et al.²⁰ reported a TG/HDL‑C ratio median (IQR) value of 4.34 (2.69–6.75) in a sample of apparently healthy urban male adults of Asian origin (Iranian), whereas the median/mean values of TG/HDL‑C ratio ranged from only 1.3 to 2.9.^21,22 in apparently healthy study populations of Caucasian origin. Literature found that TG/HDL-C has a strong association with premature CHD (23). The value of TG/HDL‑C ratio in the present study is an important observation. The median (IQR) TG/HDL‑C ratio of cases is 4.23 and 3.40 in controls. In our study healthy controls have comparatively high TG/HDL‑C ratio. So TG/HDL‑C ratio can be used as an independent surrogate marker for CAD.

 

CONCLUSION

The TG/HDL‑C ratio can be used as an independent marker of CAD. It is an easy and effective way of early detection of lipid abnormality even in the absence of any clinical signs and symptoms of disease. This marker can help to reduce the disease burden and for the improvement of public health by early detection and life style modifications.

 

REFERENCE

Source of Support: None Declared Conflict of Interest: None Declared