Initial glomerular filtration rate and survival in hemodialysis. The role of permanent vascular access.

Background: A significant increase in the number of patients starting chronic hemodialysis (HD) with an estimated glomerular filtration rate (eGFR)≥10 mL/min/1.73 m(2) was observed in Argentina between 2004 and 2009.

Methods: In order to study this topic, we calculated the mortality hazard ratios (HR) in a cohort of incident HD individuals from the Argentine Registry of Chronic Dialysis [Registro Argentino de Diálisis Crónica] (2004-2009), grouped according to the initial eGFR (0-4.9, 5-9.9, 10-14.9 and ≥15 mL/min/1.73 m(2) ; reference group 0-4.9) estimated by CKD-EPI; in three cohorts: "total population", "healthy" (<65 years, without diabetes or comorbidities) and "planned entry" (with permanent vascular access).

Results: After adjusting the population (n=16,931) for age, gender, coexisting conditions, serum albumin, income, and temporary vascular access a HR of 1.19 (95%CI:1.07-1.33) was observed in the group with eGFR≥15 mL/min/1.73 m(2). In the cohort of 3,897 "healthy" after adjusting for the same co-variates, HRs of 1.44 (95%CI: 1.08-1.65) and 1.65 (95%CI: 1.06-2.55) were obtained for the groups with baseline eGFR values of 10-14.9 and ≥15 mL/min/1.73 m(2), respectively. In "planned entry" patients (n=6,280), after adjusting for age, gender, co-morbidities, serum albumin and income, HRs in all groups were not significantly different as compared to the control group.

Conclusions: HD initiation with eGFR>10 mL/min/1.73 m(2) shows no survival advantage. The higher mortality in the group with >eGFR starting dialysis looks like an "artifact" related to higher age, more co-morbidities, low albuminemia and the use of temporary vascular access.