FP477EFFECT OF HEMODIAFILTRATION ON MORTALITY IN THE FRENCH REIN REGISTRY

Abstract

Introduction and Aims: Randomized trials about hemodiafiltration (HDF) showed conflicting results, but consistently found lower mortality risk associated with higher convection volume. Recent dialysis monitors and membranes more constantly permit to reach a high convection volume.We used data from the REIN registry to investigate the relation between HDF and mortality in the recent period. Methods: All incident patients who started hemodialysis from January 1, 2008 to December 31, 2011, dialyzed for more than 3 months, were included and followed until end of 2012. Data from REIN included age, gender, 11 co-morbidities, laboratory data and dialysis modalities including HDF. Multivariate Cox analyses for all-cause and cardiovascular mortality used HDF as a time dependent variable, age as time-scale, was stratified by region, facility type and legal status and took into account facility clustering. Interactions with co-morbidities were tested. Finally, to account for unmeasured confounders, facility-level analyses - using the yearly percentage of patients on HDF in each dialysis unit - were conducted with adjustment for patient co-morbidities and yearly percentage of catheter use by dialysis unit as another surrogate for practice center variable. Patients were censored for renal transplantation, dialysis weaning, transfer to peritoneal dialysis and move out of France. Results: Out of 28,407 included patients, 5 526 were treated with HDF for a median period of 1.2 years (0.9-1.9) of whom 2254 were exclusively treated with HDF. The medians of follow-up were 1.87 years (1.13-2.90) for the standard dialysis group and 2.33 years (1.48-3.40) for the HDF group. Patients on HDF vs standard dialysis were older (71.3 vs 70.5 y, p=0.01), more frequently diabetic (46.6 vs 38.8%, p<0.001), had more coronary heart disease (25 vs 22.3%, p<0.001), more peripheral vascular disease (22.9 vs 20.7%, p<0.001), more walking disability (14.1 vs 12.5%, p=0.01), were less likely to have polycystic kidney disease (4.1 vs 6.7%, p<0.001) and more likely to have vascular or diabetic kidney disease (27.7 vs 22.4%, p<0.001), and more frequently started dialysis in emergency (33 vs 30.2%, p<0.001), with a catheter (50.8 vs 47%, p<0.001) and in a hospital based facility (94.8 vs 89.1%, p<0.001). In multivariate Cox analyses, HDF was associated with lower all-cause and cardiovascular mortality risks: HR [95% CI], 0.83 [0.77-0.90] and 0.74 [0.62-0.88], respectively. In analysis restricted to patients exclusively treated with HDF versus never, all-cause mortality risk associated with HDF was 0.77 [0.69-0.87]. Interaction tests between co-morbidities and HDF were not significant. In the facility-level analysis restricted to patients never dialyzed in self-care dialysis unit (n=21,945 of whom 4 825 treated by HDF), those treated in 100% vs 0% HDF unit had a reduced all-cause and cardiovascular mortality: HR, 0.84 [0.75-0.96] and 0.71 [0.53-0.95], respectively. Conclusions: Patients on HDF tend to be older and have higher cardiovascular co-morbidities. Despite a higher risk profile, patients treated with HDF in the last 6 years experienced better survival, as studied both by patient-level and facility-level analyses.