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Saudi Journal of Kidney Diseases and Transplantation
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Table of Contents   
ORIGINAL ARTICLE  
Year : 2012  |  Volume : 23  |  Issue : 1  |  Page : 31-36
Evaluation of association between intima-media thickness of the carotid artery and risk factors for cardiovascular disease in patients on maintenance hemodialysis


1 Department of Nephrology and Internal Medicine, Ayatollah Taleghani Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
2 Division of Nephrology, Department of Internal Medicine, 5 Azar Medical Center, Golestan University of Medical Sciences, Golestan, Iran
3 Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran

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Date of Web Publication3-Jan-2012
 

   Abstract 

Cardiovascular disease is the most common cause of mortality and morbidity in patients with end-stage renal disease (ESRD). Atherosclerosis is a systemic disease, and carotid and coronary vessels are at comparable risk for developing pathologic changes. For this reason, increase in the thickness of the intima-media layers of carotid arteries can be a harbinger of coronary atherosclerosis and also a prognostic factor for cardiovascular accidents. In this study, we evaluated the status of carotid intima-media thickness (CIMT) in patients with ESRD on dialysis and analyzed its association with other risk factors for cardiovascular diseases. This cross-sectional study was conducted on patients referred for hemodialysis (HD) to the Taleghani Hospital (Shahid Beheshti University of Medical Sciences, Tehran, Iran) during 2007-2008. At the beginning, biochemical parameters and common cardiovascular risk factors were extracted from the patients' files, and then CIMT was measured by using B-Mode high-resolution ultrasonography, 1 cm proximal to the carotid bulb in the posterior wall. Finally, correlation between other risk factors and CIMT was made. One hundred patients with chronic and advanced renal disease were evaluated, including 46% females and 54% males. The mean age of these patients was 59.2 ± 13.1 years, with a range of 26-81 years. Correlations between CIMT and age (P = 0.023, r = 0.478), dialysis duration (P = 0.017, r = 0.435), number of cigarettes smoked (P = 0.026, r = 0.429), diastolic blood pressure (P = 0.013, r = 0.455) and fasting blood sugar (P = 0.045, r = 0.346) were significant. Risk factors for cardiovascular disease in patients on HD are of significant interest because of the high prevalence and frequency of the disease in this group of patients. However, in the present study, we were not able to find a very consistent and definite role for some risk factors in our patients. More studies are required to make clear the role of these factors in patients on HD.

How to cite this article:
Falaknazi K, Tajbakhsh R, Sheikholeslami F H, Taziki O, Bagheri N, Fassihi F, Rahbar K, Haghighi A N. Evaluation of association between intima-media thickness of the carotid artery and risk factors for cardiovascular disease in patients on maintenance hemodialysis. Saudi J Kidney Dis Transpl 2012;23:31-6

How to cite this URL:
Falaknazi K, Tajbakhsh R, Sheikholeslami F H, Taziki O, Bagheri N, Fassihi F, Rahbar K, Haghighi A N. Evaluation of association between intima-media thickness of the carotid artery and risk factors for cardiovascular disease in patients on maintenance hemodialysis. Saudi J Kidney Dis Transpl [serial online] 2012 [cited 2019 Jul 22];23:31-6. Available from: http://www.sjkdt.org/text.asp?2012/23/1/31/91296

   Introduction Top


Cardiovascular (CV) disease is the most common cause of mortality and morbidity in patients with end-stage renal disease (ESRD). Data show that CV diseases are the cause of death in 51- 55% of dialysis and 37% of kidney transplant recipient patients in the western countries. [1],[2],[3]

It has been estimated that one out of nine people in the United States suffers from chronic renal disease; on the other hand, mortality rate secondary to CV diseases is 10-30 times higher in dialysis patients and 2-5 times higher in renal transplant recipients, when compared with healthy matched subjects. [3],[4] CV manifestations in chronic renal disease include left ventricular hypertrophy, systolic and diastolic dysfunction, pulmonary artery hypertension, vascular and valvular calcification, atherosclerosis and arteriosclerosis. [5],[6]

Atherosclerosis, which is the most important cause of mortality and morbidity in patients with ESRD, begins many years before the development of clinical manifestations. [7],[8] Studies have shown that hemodialysis (HD) patients have advanced changes in the walls of their arteries, which can present as increased intima-media thickness (IMT) in the carotid and femoral arteries. [9],[10] Considering the fact that atherosclerosis is a systemic disease and carotid and coronary vessels have equivalent risks for developing atherosclerosis, increased carotid IMT (CIMT) can be used as a sign of atherosclerosis in the coronary arteries and as a prognostic factor after CV accidents. [11] In multiple studies, a significant association has been shown between pathologic changes in coronary vessels and increased IMT in the carotid arteries. [3] This study was designed and carried out because we believe that vascular changes in HD patients are very important in the course of the disease and the CIMT is highly correlated with other CV risk factors in our population. In this article, we present our findings on the use of high-resolution carotid ultrasonography as a non-invasive technique for diagnosing, and thus slowing or halting the progress of atherosclerosis in patients on dialysis.


   Materials and Methods Top


This was a cross-sectional study in which all patients with renal failure, who were referred for HD to the Ayatollah Taleghani Hospital (Shahid Beheshti University of Medical Sciences, Tehran, Iran) during 2007-2008 and fulfilled the inclusion criteria of the study, were evaluated. The inclusion criteria were: patients with ESRD on regular HD and who gave written consent for participating in the study. Patients in whom carotid Doppler ultrasonography could not be performed were excluded from the study. Data needed for the study were extracted from the files of patients (regarding CV risk factors). In this study, ESRD was defined as chronic advanced kidney disease in which the glomerular filtration rate (GFR) was less than 15 mL/min. Diabetes was defined as the presence of hyperglycemic symptoms (polyuria, polydipsia) plus random blood glucose concentration ≥200 mg/dL or fasting blood sugar ≥126 mg/dL. [12] Hypertension was defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg. [13] Obesity was defined as body mass index (BMI) >30 kg/m 2 , [14] and hyperlipidemia was defined as plasma cholesterol levels ≥240 mg/dL or plasma low-density lipoprotein (LDL) levels ≥160 mg/dL [15] or plasma triglyceride levels ≥150 mg/dL. [16] Carotid Doppler ultrasonography was performed by a single operator at the patients' bedside and IMT was measured; the operator was blinded about the history and laboratory findings of the patients.

The IMT was defined as a hypo-echogenic space between two echogenic lines containing intima-media interface and media-adventitia interface on the posterior wall of the carotid artery. [9],[17],[18] For performing carotid Doppler ultrasonography, the patient was asked to lie down on the examination table in the supine position. His/her neck was rotated in a superior and leftward direction so that the right carotid artery was exposed. Following this, using a B-mode high-resolution ultrasonography system (I-look 25, manufactured by American Sono-Site Factory, Denver, Colorado), the length of the artery was determined, and at the site of bifurcation of the common carotid artery (carotid bulb), the posterior wall was exposed and IMT was measured. If atherosclerotic plaques were found on the carotid artery, their presence and number were recorded on the data collection forms. For assurance about correctness of data, images were recorded in the memory of the system and and reviewed later. In this study, an atherosclerotic plaque was defined as a local thickness of intima greater than 1 mm or two times more than its adjacent normal layer. [14]

For statistical analysis of data, ratio and rate were used for qualitative variables and mean and standard deviation for quantitative data. Also, χ2 test was used for comparison of rates and t-test was used for comparison of means. Correlation test was used for evaluating the association of quantitative variables. In this study, statistical significant level was considered as P value <0.05 and SPSS version 11 software was used for data analysis.


   Results Top


In this study, 100 patients with advanced and chronic renal disease were evaluated; 46% were males and 54% were females. Their mean age was 59.2 ± 13.1 years (range 26-81 years). Past medical history revealed that 44 patients were diabetic (44%), 70 patients (70%) hypertensive, 16 had history of myocardial infarction (MI), six had history of cardiovascular accident (CVA) and 16 were smokers. The mean number of cigarettes smoked in this group was 143.75 ± 23.4 cigarettes/ year, with a range of 50-200 cigarettes/year. The mean duration on dialysis was 3.75 ± 4.14 years (range 2-21 years). The mean BMI was 24.88 ± 3.75 Kg/m 2 (range 18.6 to 35.9); the mean systolic blood pressure was 142.4 ± 23.4 mmHg (range 110-190 mmHg) and mean diastolic blood pressure was 77.6 ± 7.44 mmHg (range 60-90 mmHg).

On high-resolution carotid ultrasonography, carotid plaques were detected in 56 patients (56%). Among them, 67.8% had a single plaque and 32.2% had two or more plaques. The mean right CIMT was 0.936 ± 0.304 mL (range 0.40- 1.80 mL). The results of serum bio-chemical tests have been summarized in [Table 1]. Correlation coefficients between right CIMT and quantitative variables in the study for detecting their associations are shown in [Table 2]. The means of studied variables in patients with and without plaques in the carotid artery are shown in [Table 3].
Table 1: Results of the laboratory tests in the studied patients (N = 100).

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Table 2: Correlation coefficient between right carotid intima– media thickness and quantified variables in the studied patients.

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Table 3: Mean of the evaluated variables in patients with and without plaques in the carotids.

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Data in this study show that 60.9% of female patients and 63% of male patients had plaques in their carotids. The difference was not statistically significant (P > 0.05). In patients with history of diabetes, the prevalence of carotid plaques was 46.4% compared with 18.8% in non-diabetic patients; this difference was statistically significant (P = 0.011). In patients with a history of hypertension, 65.7% had carotid plaques compared with 33.3% in the normotensive patients. Comparison of these rates by χ2 test showed a statistically significant difference (P = 0.035). In patients with a history of MI, 75% had carotid plaques compared with 59.5% in patients with no history of MI. This difference was not statistically significant (P > 0.05). About 33.1% of the patients with a history of CVA had carotid plaques compared with 63.8% without history of CVA, a difference which was not significant (P> 0.05). Among patients with history of smoking, 75% had carotid plaques compared with 39.5% among non-smokers; this difference was statistically significant (P = 0.011). Patients with longer duration on dialysis and elderly patients had high IMT (P = 0.017 and 0.023, respectively).


   Discussion Top


Atherosclerosis is a systemic disease and both carotid and coronary vessels are at equal risk for developing it. For this reason, increased CIMT is a harbinger of coronary atherosclerosis and a prognostic factor for CV outcome. In addition, the risk factors for involvement of both arteries are more or less similar. Our findings suggest that presence of diabetes is significantly associated with increased CIMT. Similar findings have been reported by Modi et al from India [17] and Ishimura et al from Japan. [19] It seems that diabetes acts as a risk factor for developing atherosclerotic plaques in patients on HD.

In our study, there was no association between history of MI and CVA, and CIMT, which is different from the findings of Modi et al. [17] The difference may be related to the existence of multiple risk factors in this group of patients; thus, the other risk factors might have a role to play in patients with increased CIMT and without previous history of MI. In this regard, smoking has shown a significant association.

Our study shows a direct and significant correlation between CIMT and duration on dialysis; the CIMT increased with a direct association with duration on dialysis. In our study, age of the patients had a positive and somewhat significant association with CIMT such that in the older patients, average level of CIMT was more than in the younger group. Similar results have been found by Modi et al. [17] These results are predictable when one understands the pathophysiology of atherosclerosis and its known association with aging process.

Our study showed a direct association between diastolic blood pressure and CIMT. Such association was not seen for systolic blood pressure. In the study of Abdolghaffar et al, [20] a significant association between systolic and diastolic blood pressure and CIMT was noted in non-HD CRF patients. Ishimura et al from Japan [19] and Hakan et al from Turkey [18] failed to show significant association between these two variables.

Based on our findings, diabetes is a risk factor for developing plaques in the carotids. However, there was no significant correlation between CIMT and other estimated variables. Definite conclusions about correlation between other evaluated variables and CIMT can be drawn only after further studies with more participants.

We conclude that there is a significantly increased frequency and prevalence of CV risk factors in patients on HD. These factors, based on previous investigations, play a key role in the development of atherosclerosis. In this study, age, dialysis duration, number of cigarettes smoked, diastolic blood pressure and diabetes were shown to be atherogenic. More investigations on this field and with a larger sample size could make clear the role of these factors in patients on HD.

 
   References Top

1.Ehrich JH, Loirat C, Brunner FP, et al. Report on management of renal failure in children in Europe, 1991. Nephrol Dial Transplant 1991; 7(suppl 2):36-48.  Back to cited text no. 1
    
2.Disney AP. ANZDATA report 1996. Australia newzealand dialysis and transplant Registry, Adalide. 1996.  Back to cited text no. 2
    
3.Sarnak MJ, Levrely AS, Schoolwerth AC, et al. Kidney disease as a risk factor for development of cardiovascular diseases: a statement from the American heart association councils on kidney in vascular disease, high pressure research, clinical cardiology, and Epidemiology and prevention. Circulation 2003;108:2154-69.  Back to cited text no. 3
    
4.Moe SM, Chen NX. Pathophysiology of vascular calcification in chronic kidney disease. J Am Heart Assoc 2004;95(6):560-7.  Back to cited text no. 4
    
5.Foley RN, Parfrey PS, Sarnak MJ. Clinical epidemiology of cardiovascular disease in chronic renal disease. Am J Kidney Dis 1998; 32(suppl 3):5112-9.  Back to cited text no. 5
    
6.Sarnak MJ. Cardiovascular complications in chronic kidney disease. Am J Kidney Dis 2003;41(suppl):511-7.  Back to cited text no. 6
    
7.Lindner A, Charra B, Sherraol DJ, Serbner BH. Accelerated atherosclerosis in prolonged maintenance hemodialysis. N Engl J Med 1975;290:697-701.  Back to cited text no. 7
    
8.Ross R. The pathogenesis of atherosclerosis. N Engl J Med 1993;392:801-9.  Back to cited text no. 8
    
9.Kawaghishi T, Nishizawa Y, Konishi T, et al. High resolution B-Mode ultra sonography in evaluation of atherosclorosis. N Engl J Med 1974;200:697-701.  Back to cited text no. 9
    
10.Shoji T, kawaghishi T, Emoto M, et al. Additive impact of diabetes and renal failure on carotid atherosclerosis. Atheroclerosis 2000; 153:257-8.  Back to cited text no. 10
    
11.Jadhv UM, Kadam NN. Carotid intima-media thickness as an independent predictor of coronary artery disease. Indian Hearts J 2001;53: 458-62.  Back to cited text no. 11
    
12.Genuth S, Alberti KG, Bennett P, et al. Follow-up report on the diagnosis of diabetes mellitus. Diabetes Care 2003;26:3160.  Back to cited text no. 12
    
13.Chobanian AV, Bakris GL, Black HR, Cushman, WC. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report. JAMA 2003;289:2560.  Back to cited text no. 13
    
14.World Health Organization. Obesity: preventing and managing the global epidemic. Report of a WHO convention, Geneva, 1999. WHO technical report series 894, Geneva 2000.  Back to cited text no. 14
    
15.Executive summary of the third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (adult treatment panel III). JAMA 2001;285:2486,  Back to cited text no. 15
    
16.Third report of the National Cholesterol Education Program (NCEP) Expert Panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). Circulation 2002;106:3143.  Back to cited text no. 16
    
17.Modi N, Kappor A, Kumar S, Tewari S, Garey N, Shinha N. Utility of carotid intima- media thickness as a screening tool for evaluation of coronary artery disease in pretransplant end Stage renal disease. J Postgard Med 2006;52 (4):266-70.  Back to cited text no. 17
    
18.Poyrazoðlu HM, Düºünsel R, Yikilmaz A, et al. Carotic artery thickness in children and young adult with ESRD. Pediatr Nephrol 2007;27:109-16.  Back to cited text no. 18
    
19.Ishimura E, Taniwaki H, Tabata T, et al. Cross sectional association of serum phosphate with carotid intima-media thickness in hemodialysis patients. Am J Kidney Dis 2005:45(5):859-69.  Back to cited text no. 19
    
20.Abdelghaffar S, El Amir M, El Hadidi A, El Mougi F. Carotid intima-media thickness: An index for subclinical atherosderosis in type I diabetes. J Trop Pediatr 2006;52(1):39-45.  Back to cited text no. 20
    

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Correspondence Address:
R Tajbakhsh
Nephrology Division, Department of Internal Medicine, 5 Azar Medical Center, Golestan University of Medical Sciences, Golestan
Iran
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    Tables

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