Association of visceral fat thickness with carotid atherosclerosis and inflammation in peritoneal dialysis patients

Abstract

Background:Patients with advanced chronic kidney disease (CKD) requiring maintenance dialysis have a significantly higher risk of cardiovascular mortality. In general population, anthropometric measurements of central obesity such as high body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) are associated with increased cardiovascular mortality. However, the association between obesity and clinical outcomes in patients with peritoneal dialysis (PD) is conflicting. The aim of this study was to investigate whether visceral fat thickness had predictive role in carotid atherosclerosis determined by carotid intima-media thickness (cIMT) in PD patients. Methods:A cross-sectional study was undertaken in 88 prevalent PD patients between February 2010 and July 2010. BMI, WC, and WHR were measured as anthropometric indices of obesity. Visceral fat thickness (VFT) and subcutaneous fat thickness (SFT) were determined by sonographic measurement of abdominal fat. cIMT was measured as a surrogate marker of atherosclerosis. Carotid atherosclerosis was defined as cIMT ≥1 mm. Results:The mean age was 53.3 ± 11.8 years and the mean duration of PD was 63.6 months. Fifty-four patients (61.4%) were male and 22 patients (25%) were diabetes. The mean cIMT was 0.76 ± 0.26 mm, and the prevalence of carotid atherosclerosis was 20.4% (18/88). Patients with carotid atherosclerosis had significantly higher WC (89.4 ± 9.9 vs. 83.7 ± 7.8 cm, p = 0.033), higher WHR (0.94 ± 0.05 vs. 0.91 ± 0.05, p = 0.038), and higher VFT (42.5 ± 15.1 vs. 32.2 ± 8.9 mm, p <0.001) compared to patients without carotid atherosclerosis. In univariate analysis, VFT [Odds ratio (OR) = 1.085, 95% Confidence interval (CI): 1.032-1.14, p = 0.001], WHR (OR = 1.105, 95% CI: 1.033-1.218, p = 0.043), BMI (OR = 1.24, 95% CI: 1.029-1.494, p = 0.024), and WC (OR = 1.085, 95% CI: 1.016-1.158, p = 0.014) were significant risk factors of carotid atherosclerosis. However, multivariate logistic regression analysis revealed VFT was a single independent factor associated with carotid atherosclerosis after adjustment of demographic and biochemical parameters (OR = 1.089, 95% CI: 1.021-1.161, p = 0.009). Moreover, VFT remained as an independent risk factor of carotid atherosclerosis in multivariate logistic regression analysis for comparison of relative independent association of obesity indices with carotid atherosclerosis (OR = 1.095, 95% CI: 1.004-1.194, p = 0.04). The respective areas under the receiver operating characteristic curve (AUC) of VFT was higher than the AUCs of all other parameters (VFT; AUC 0.705, p=0.007). When the patients were divided into three groups according to VFT, patients with high VFT tertile showed higher inflammatory markers such as high sensitivity C-reactive protein and fibrinogen, and higher insulin resistance compared to other groups. Conclusion: The main finding of this study is VFT, not SFT, is more predictive for carotid atherosclerosis than all other obesity indices in PD patients. Although WC and WHR showed significant relationships with carotid atherosclerosis in univariate analysis, VFT measured by abdominal ultrasonography was an independent risk factor of carotid atherosclerosis after adjustment for confounding variables. Therefore, sonographic measurement of VFT could be useful to stratify the risk of cardiovascular outcomes in PD patients.