Quality of Life of Patients

This study will compare the impact of two hemodialysis techniques on fatigue and post-dialysis recovery time in patients aged 85 years and older. These two techniques are high-flux hemodialysis (HD) and hemodiafiltration (HDF). Patients will receive the treatment over two periods: if period 1 is HD then period 2 will be HDF. Every patient will be his/her own control, this is why it is called cross-over. Each period will last three months. Between the two periods, patients will receive a traditional low-flux hemodialysis. These two techniques are widely used worldwide and their side-effects are well-known and do not put the patients at risk. HDF has been shown to improve survival in patients with a mean age of 58 years. But a previous study from the investigators' group showed that HDF causes a prolonged recovery time in older patients. This randomized trial aims to elucidate this question.