| Abstract|| |
Carotid intimal-medial thickness (CIMT) predicts future vascular events in the general population. However, the correlation of traditional cardiovascular risk factors and stages of chronic kidney disease (CKD) with CIMT is not studied extensively. To determine the correlation of CIMT with traditional cardiovascular risk factors like age, body mass index (BMI), dyslipidemia and various stages of CKD patients, CIMT was measured by means of high-resolution B-mode ultrasonography in 70 CKD patients and compared with the 30 healthy controls. The mean CIMT in patients was 0.86 ± 0.21 mm vs 0.63 ± 0.17 mm in healthy age- and sex-matched controls (P <0.001). There was a significant univariate positive correlation between CIMT and age (r = 0.605, P <0.001), BMI (r = 0.377, P = 0.001), total cholesterol (r = 0.236, P ≤0.018) and serum triglyceride (r = 0.387, P ≤0.001). No statistically significant correlation was found between mean CIMT and estimated glomerular filtration rate (eGFR) (r = -0.02, P = 0.30), very low-density lipoprotein and high-density lipoprotein-cholesterol. Atherosclerotic changes very well correlate with the traditional cardiovascular risk factors like age, BMI, serum total cholesterol and serum triglyceride level in CKD patients. Even though CIMT was marginally more in the late stages of CKD patients, no statistically significant correlation was found with CIMT and eGFR.
|How to cite this article:|
Chhajed N, Subhash Chandra B J, Shetty MS, Shetty C. Correlation of carotid intimal-medial thickness with estimated glomerular filtration rate and cardiovascular risk factors in chronic kidney disease. Saudi J Kidney Dis Transpl 2014;25:572-6
|How to cite this URL:|
Chhajed N, Subhash Chandra B J, Shetty MS, Shetty C. Correlation of carotid intimal-medial thickness with estimated glomerular filtration rate and cardiovascular risk factors in chronic kidney disease. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2021 Oct 21];25:572-6. Available from: https://www.sjkdt.org/text.asp?2014/25/3/572/132186
| Introduction|| |
Chronic kidney disease (CKD) is associated with premature mortality, decreased quality of life and increased health care expenditures. , Many patients with CKD have cardiovascular disease and die prematurely from this condition instead of surviving long enough to face dialysis or transplantation. , Surveys have shown that the risk for cardiovascular disease increases at much earlier stages of renal disease, as CKD patients have an excess of traditional risk factors for cardiovascular disease, such as hypertension, diabetes and hyperlipidemia.  Renal disease also engenders an environment that promotes cardiovascular injury in ways that are more or less specific to CKD. Calcium and phosphorous dysregulation with vascular calcification, anemia and hyper-homocysteinemia are among the most often cited cardiovascular liabilities of CKD. 
Most evidence about the nature of the vascular disease in CKD patients stems from those on chronic dialysis, and there is little information about how this disease evolves in the early stages of the disease and whether it correlates with the traditional risk factors such as dyslipidemia, diabetes and hypertension; this is more difficult to determine because overt cardiovascular disease is less common in patients with mild renal impairment.
Atherosclerosis, unless in a severe form, is often asymptomatic; hence, a direct examination of vessel wall is necessary to detect the affected individuals in early stages. Carotid artery intimal-medial thickness (CIMT) is a well-established index of systemic atherosclerosis that correlates well with the incidence of coronary heart disease and stroke in the CKD population. ,,
The aim of our study was to determine the relationship between dyslipidemia and atherosclerosis in CKD patients through the measurement of CIMT.
| Patients and Methods|| |
We studied 70 CKD patients at the Medicine/ Nephrology inpatient/outpatient department of the JSS Hospital, Mysore, and 30 age- and sex-matched controls. We excluded from the study patients with acute renal failure (ARF), those with a history of carotid surgery, those less than 18 years of age, smokers, alcoholics and those who were on hypolipidemic drugs or having a previous history of ischemic heart disease or stroke. The study patients were investigated with complete hemogram, urinalysis, blood urea levels, serum creatinine levels and lipid profile [total cholesterol, triglycerides and high-density lipoprotein -cholesterol (HDL-C), low-density lipoprotein-cholesterol and very low-density lipoprotein-cholesterol (VLDL-C)]. All the biochemical parameters were measured according to the standard laboratory techniques. Glomerular filtration rate (GFR) was calculated using the modification of diet in renal disease (MDRD) formula.
The CIMT was measured using B-mode ultrasound and a 7.5 MHz transducer. Intimal-medial thickness was defined as the distance between the leading edge of the first echogenic line (lumen-intima interface) and the second echogenic line (media-adventitia interface) of the far wall. Three measurements were taken at 0.5, 1 and 2 cm below the carotid bifurcation of the common carotid artery on each side, and their arithmetic averages were calculated. The intimal-medial thickness of both sides (right and left) was also calculated and the average of these two values was calculated. All the CIMT measurements were performed by a single radiologist. The presence of plaques was noted. Plaques were defined as focal widening relative to the adjacent segment, with protrusion into the lumen. The extent of the lesions was not quantified.
| Statistical Analysis|| |
The statistical software SPSS Ver. 13 was used for statistical analysis. The mean ± standard deviation was calculated. Pair-wise comparison between the cases and controls was performed for all parameters using Student's Unpaired t-test. The values of P <0.05 were considered as significant. The qualitative variables were compared using the chi-square test. Univariate correlation analysis was used to confirm the significance of the variables of the CIMT.
| Result|| |
The study patients comprised 39 men and 31 women with a mean age of 44.5 years (range 20-75 years). The mean estimated glomerular filtration rate (eGFR) was 17 ± 18.4 mL/ min/1.73 m 2 .
When the study group was divided according to the Kidney Disease Outcomes Quality Initiative (KDOQI) stages, there were 43 patients in stage 5 (eGFR <15 mL/min), 14 in stage 4 (eGFR 15-29 mL/min), 6 in stage 3 (eGFR 30-59 mL/min) 6 in stage 2 (GFR 60-89 mL/min) and 6 in stage 1 (eGFR >90 mL/min). Diabetes was the leading etiology of CKD in 29 (41.4%) patients, chronic glomerulonephritis in 13 (18.6%) patients and essential hypertension in 11 (15.7%) patients. CIMT was significantly increased in the patient group (CIMT 0.86 ± 0.21 mm compared with the control group (0.63 ± 0.17 mm) [Figure 1] (P <0.001). The mean CIMT in CKD patients significantly correlated with traditional risk factors including age (r = 0.605; P <0.001), body mass index (r = 0.377; P <0.001), serum triglyceride levels (r = 0.387; P <0.001) and serum cholesterol (r = 0.236; P <0.018) [Figure 2]. However, no correlation of CIMT was observed with calcium-phosphorous product (r = 0.184, P = 0.13), serum HDL-C (r = 0.191; P = 0.057), VLDL-C (r = 0.08; P = 0.398) and LDL (r = 0.233; P = 0.019). There was a statistically significant difference of the mean CIMT in diabetic (0.93 ± 0.25) and non- diabetic patients (0.80 ± 0.14) (P ≤0.01) [Figure 3]. Mean CIMT did not directly correlate with eGFR (r = -0130, P <0.283).
|Figure 1: Distribution of subjects by mean carotid intimal–medial thickness (CIMT) values.|
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|Figure 2: Correlation between carotid intimal–medial thickness (CIMT) and age, body mass index (BMI), triglyceride (TG) and total cholesterol (TC).|
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|Figure 3: Distribution of mean carotid intimal– medial thickness (CIMT) in diabetic chronic kidney disease (CKD) and non-diabetic CKD patients.|
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| Discussion|| |
The results of this study show that the CIMT is significantly increased in the pre-dialysis CKD patients compared with controls. CIMT measurement is a non-invasive technique to predict the atherosclerotic burden in these patients.
In a study by Shoji et al,  no significant difference was found in the CIMT between the pre-dialysis CKD and hemodialysis patients (P = 0.821). They concluded that atherosclerosis might be caused by renal failure and/or metabolic abnormalities secondary to renal failure. In contrast, a study by Kennedy et al  found an increased CIMT in pre-dialysis patients. Preston et al  reported that patients with stage 3 to 4 CKD had increased CIMT compared with normotensive volunteers. Lu Xia Zhang et al,  in their study on stage 2-3 CKD patients (i.e., mild and moderate renal insufficiency), found significantly increased CIMT in these patients and concluded that arterial change might occur in the course of CKD earlier than previously believed.
Previous studies showed that CIMT was associated with traditional atherosclerotic risk factors (such as age, obesity, dyslipidemia and diabetes) as well as factors that reflect the state of inflammation: Fibrinogen, C-reactive protein, leptin, adhesion molecules, growth factors or serological markers of certain viral infections. ,,, In our study, we did not find a difference in eGFR between subjects with and without increased CIMT. In the linear regression model, factors associated with CIMT were predominantly traditional atherosclerotic risk factors, whereas eGFR was not independently associated with CIMT, which indicates that increased CIMT in patients with CKD might be caused at least in part by traditional risk factors.
A population-based study from Canada  showed that ethnicity or other factors linked to ethnicity might mediate the effect of atherosclerosis on the risk for cardiovascular disease. Therefore, findings from the western countries could not be fully extrapolated to Indians. Therefore, additional studies are needed to evaluate the relation between CIMT and cardiovascular events or mortality in the different races of patients with CKD.
There were certain limitations to our study. First, its cross-sectional design limited the conclusion on the mechanism or temporal relation. Non-traditional risk factors for atherosclerosis, such as serum homocystine levels, lipoprotein (Lpa), etc., were not studied. Therefore, further studies are required to determine the mechanism of atherosclerosis in early stages of kidney disease. Measurement of arterial wall stiffness will provide additional information regarding the effects of renal failure on functional changes of the arterial walls in patients with CKD.
In summary, our study indicates that in our population, arterial changes were observed in the early stage of CKD. In addition to age, sex and systolic blood pressure, increased total cholesterol and triglyceride levels were related independently to the CIMT. Traditional factors might contribute to the increased CIMT, whereas the relationship between this increase and patient prognosis needs to be investigated further.
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Dr. Nitesh Chhajed
Department of Medicine, JSS Medical College, Mysore, Karnataka
[Figure 1], [Figure 2], [Figure 3]