SURVIVAL ANALYSIS OH HAEMODIALYSIS PATIENTS: IMPACTO OF UREMIC TOXINS

Abstract Background and Aims HEMO study showed that β2M level over time was predictive of all-cause mortality in haemodialysis patients (HD). Later studies suggested that protein-bound uremic toxins are associated with mortality in HD patients but with recent contrasting results. Aim of study was to analyse β2M and indoxyl sulfate (IS) as predictor factors of mortality. Method 5 years follow-up of 60 prevalent HD patients of our hospital. Demographic data was described. Baseline midweek pre-dialysis serum β2M was determined by nephelometry and total IS levels by high performance liquid chromatograph connected to a UV detector. We considered high serum β2M group as if was equal or higher than 27,5 mg/L. As to IS, patients were divided into quartiles (1q <9,7 mg/L, 2-3q ≥9.7-26.5mg/L, 4q>26.5 mg/L). Survival curves were assessed using the Kaplan–Meier analysis at 1,2,3 and 5 years in univariate analysis for albumin (≥38 g/L or lower), β2M, and total IS groups, and evaluated by the proportional hazards Cox´s model. P -values <0.05 were considered statistically significant. Results 60 prevalent patients with mean vintage of 46,8 months (range 3-299 months). Mean age was 60±20 years. Males were more prevalent (53,3% vs 46,6%). 35% had diabetes. 51,6% underwent conventional hemodialysis (HD), 48,3% post-dilution haemodiafiltration, with mean convective volume of 23,8±2,8L. Mean eKt/V was 1,67±0,4, mean nPCR was 1±0,27g/kg/day. Only 8,3% of patients had urine volume>500cc/24hours. Mean β2M level was 35,6±1,9mg/L (X±SE) and mean total IS level was 18,9±1,6mg/L. The overall mortality at 5 years was 57%. Albuminemia lower than 38g/L was associated with mortality at 2, 3, and 5-years in univariate analysis (Cox´s F test p=0.03, figure 1). We found no difference in survival rate between patients with high or low serum β2M levels at 3- or 5-years analysis (Cox´s F test p=0.27). At 2 years analysis, patients in the lower β2M group had better survival (Cox´s F test p=0.04, Figure 1). There was no statistically significant association between albumin, β2M, IS level and all-cause mortality on Cox regression multivariate analysis. We observe no statistically significant association between IS levels and all-cause mortality neither on univariate, nor on multivariate analysis. Conclusion β2M < 27,5 mg/l was associated with better survival at 2 years univariate analysis. IS had no statistically significant association with all-cause mortality in our cohort.