Timing of dialysis initiation and survival in ESRD.

BACKGROUND AND OBJECTIVES The optimal time of dialysis initiation is unclear. The goal of this analysis was to compare survival outcomes in patients with early and late start dialysis as measured by kidney function at dialysis initiation. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We performed a retrospective analysis of patients entering the U.S. Renal Data System database from January 1, 1995 to September 30, 2006. Patients were classified into groups by estimated GFR (eGFR) at dialysis initiation. RESULTS In this total incident population (n = 896,546), 99,231 patients had an early dialysis start (eGFR >15 ml/min per 1.73 m(2)) and 113,510 had a late start (eGFR ≤5 ml/min per 1.73 m(2)). The following variables were significantly (P < 0.001) associated with an early start: white race, male gender, greater comorbidity index, presence of diabetes, and peritoneal dialysis. Compared with the reference group with an eGFR of >5 to 10 ml/min per 1.73 m(2) at dialysis start, a Cox model adjusted for potential confounding variables showed an incremental increase in mortality associated with earlier dialysis start. The group with the earliest start had increased risk of mortality, wheras late start was associated with reduced risk of mortality. Subgroup analyses showed similar results. The limitations of the study are retrospective study design, potential unaccounted confounding, and potential selection and lead-time biases. CONCLUSIONS Late initiation of dialysis is associated with a reduced risk of mortality, arguing against aggressive early dialysis initiation based primarily on eGFR alone.