The investigators developed a prospective, randomized, controlled trial to compare strict volume control using bioimpedance (using the BCM - Body Composition Monitor device) versus traditional clinical volume control in hemodialysis patients and the impact on mortality, hydration status, blood pressure values and arterial stiffness.

The investigators developed a randomized controlled study to compare exclusively bioimpedance guided ultrafiltration in hemodialysis patients versus traditional methods for volume assessment.

The duration of the study was 3,5 years.

During the first 2,5 years of the study all enrolled patients were randomized using a block randomization algorithm in two arms.

In the interventional arm the post-dialysis dry weight was prescribed exclusively using the BCM device (Body Composition Monitor - Fresenius Medical Care, Germany).

In the control arm dry weight assessment was done by traditional clinical methods.

In both arms,during the intervention period (2,5 years) BCM measurements were performed every 3 months before dialysis, but only in the interventional arm the values were disclosed to the medical personnel and used to guide the dry weight and ultrafiltration volumes.

In the control arm (clinical), both patients and caregivers were fully blinded from the BCM results.

The BCM device measures for each patient an ideal dry weight interval ( +/- 1.1 kg). In the interventional arm, the prescribed dry weights of the patients were strictly maintained in the ideal weight interval (+/- 1.1 kg) proposed by the BCM device.

Primary outcome was all cause-mortality compared in the strict bioimpedance arm versus the clinical (control) arm and was assessed at 2,5 years.

Secondary end-points, assessed during the randomization period (2,5 years), were to compare blood pressure (determined pre dialysis), arterial stiffness and relative fluid overload (RFO = overhydration/ total body water), as measured by the BCM device.

During the last year of the study, all patients were left free of any intervention, and only arterial stiffness was assessed a third time at 3,5 years.

Inclusion Criteria:

• older than 18-year
• on chronic hemodialysis for more than 3 months

Exclusion Criteria:

- life expectancy of less than 1 year

Presence of a condition that may interfere with the determination of dry weight using the Body Composition Monitor (R):

• severe ascites (decompensated liver failure)
• limb amputations
• cardiac stent, pacemaker or defibrillator
• hip prosthetic
• pregnancy
• mental deficiency (impossibility to give consent)