In a prospective study on CAPD patients, for every increase of 1 ml/min of GFR, the relative risk (RR) of death decreased 50%. In the CanUsa study, using the time-dependent Cox multivariate analysis, a 5% reduction in RR of death was observed for each 5L/week of residual renal GFR at baseline (7). These results suggest that, at least in elderly patients, the fast decline of GFR observed after the start of dialysis could be another cause of the low survival rate.