Progression of residual renal function with an increase in dialysis: haemodialysis versus peritoneal dialysis.

OBJECTIVE: The main objective of the study was to analyse the progression of residual renal function according to the dialysis technique (peritoneal dialysis or haemodialysis) and the frequency of treatment (two or three sessions of haemodialysis per week). As secondary objectives, we studied the progression of the serum concentration levels of β2 microglobulin and the response of anaemia to erythropoietic agents. MATERIAL AND
METHOD: 193 non-anuric patients were included and began renal replacement therapy with dialysis in our hospital between 1 January 2006 and 31 December 2011, with a follow-up period of over three months. 61 patients (32%) began treatment with two haemodialysis sessions per week, 49 patients (25%) with three haemodialysis sessions per week and 83 patients (43%) with peritoneal dialysis. The glomerular filtration rate was measured as the mean of the renal clearances of urea and creatinine.
RESULTS: The rate of decrease in glomerular filtration was the same in patients who began treatment with two haemodialysis sessions per week and with peritoneal dialysis (median 0.18 ml/min/month) and it was higher in patients who began treatment with three sessions of haemodialysis per week (median 0.33 ml/min/month, P<.05). Throughout progression, the glomerular filtration rate did not display differences between the group that began with two weekly sessions of haemodialysis and the group on peritoneal dialysis, and it was lower in the group that began treatment with three sessions of haemodialysis per week with statistical significance during the first 24 months of follow up. In the three patient groups, β2-microglobulin concentration increased as the glomerular filtration rate decreased and it was higher in the group on three weekly haemodialysis sessions for the first 12 months of follow up. In all the controls carried out, there was a negative correlation between the beta-2 microglobulin concentration and the glomerular filtration rate (P<.001). The erythropoietin dose was negatively related to glomerular filtration. Patients who began with two sessions of haemodialysis per week required a lower dose of erythropoietin than patients that began renal replacement therapy with three weekly sessions. The erythropoietin dose in the peritoneal dialysis group was below that of the group of two weekly haemodialysis sessions despite maintaining a similar glomerular filtration rate.
CONCLUSIONS: Patients who begin treatment with two sessions of haemodialysis per week experience the same rate of decrease in residual renal function as patients treated with peritoneal dialysis. The progression of the concentration of β2-microglobulin is parallel to that of the glomerular filtration rate. Patients treated with two haemodialysis sessions require a lower dose of erythropoietin than those who receive three sessions per week, but a significantly higher dose than those treated with peritoneal dialysis, which suggests that the response of anaemia to erythropoietic agents is not only related to residual renal function, but also to other factors that are inherent to the dialysis technique.