Factors associated with aortic stiffness and its change over time in peritoneal dialysis patients

Abstract

Background. An increase in aortic stiffness, as reflected by an increase in pulse wave velocity (PWV), is an important predictor of cardiovascular mortality in dialysis patients. Decreased serum concentration of calcification inhibitor, such as fetuin-A, is inversely related to mortality in haemodialysis patients. Our aim is to investigate the factors associated with aortic stiffness and its change over time in peritoneal dialysis (PD) patients. Methods. As a prospective observational study, we analysed 67 PD patients, aged 50 +/- 14 years (mean +/- SD) and with dialysis duration of 26 (5-58) months (median, interquartile range). At baseline, age, mean arterial pressure (MAP), left ventricular mass (LVM) index, diabetes, serum albumin, calcium (Ca), phosphorus (P) and intact parathyroid hormone (iPTH), uric acid, total bilirubin, high-sensitivity C-reactive protein (hsCRP), fetuin-A, and residual renal function were included in association analysis with aortic stiffness represented by heart-to-femoral PWV (hfPWV). We also evaluated simple vascular calcification score (SVCS) with plain radiograph of the pelvis and both hands. PWV was measured both at baseline and at 1 year. Change of aortic stiffness was determined by Delta PWV (difference between 1-year PWV and baseline PWV). Time-averaged concentrations were used to evaluate the relation between biologic markers and changes of aortic stiffness. Results. hfPWV was 1022 +/- 276 cm/s at baseline, and hfPWV determined at 1 year was 1069 +/- 317 cm/s. Mean serum fetuin-A concentration was 0.34 +/- 0.08 g/L. At baseline, aortic PWV positively correlated with age, smoking status, diabetes, MAP, total cholesterol and LDL cholesterol. On the other hand, aortic PWV inversely correlated with fetuin-A, log PTH, haemoglobin and albumin. In a multiple regression model, association of serum fetuin-A (beta = -0.329, P = 0.003) with aortic PWV remained significant, along with age (beta = 0.512, P < 0.001), MAP (beta = 0.215, P = 0.047) and log PTH (beta = -0.269, P = 0.025). At follow-up, Delta MAP (beta = 0.500, P < 0.001) and time-averaged TG (aTG) (beta = 0.259 P = 0.019) were determinants of Delta PWV. Conclusions. For our PD patients, serum fetuin-A was an independent determinant of aortic stiffness, as well as age, MAP and log PTH. Although 1 year is not sufficient to observe the change of aortic stiffness, some patients exhibited >15% increase of PWV during this period. Delta MAP and aTG were factors affecting the change of PWV. Follow-up over a longer period is necessary to elucidate factors that determine changes of aortic stiffness over time from PD patients.