Pulse wave velocity (PWV), an index of aortic stiffness, is measured using an automatic computerized recorder at 0, 24 and 52 weeks. The results will be analyzed by the Complior SP program (Artech Medical, France). Briefly, pressure-sensitive transducers are placed over the neck (carotid artery), wrist (radial artery) and groin (femoral artery) with the patient in the supine position on day of haemodialysis treatment before putting patient to the dialysis machine. PWV of the carotid-femoral and carotid-radial territory is calculated by dividing the distance between the sensors by the time corresponding to the period separating the start of the rising phase of the carotid pulse wave and that of the femoral and also the radial pulse waves. The procedure takes 10 to15 seconds to complete. The test will be performed by the same observer to eliminate effect of intra-observer variation.