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 m²) and 113,510 had a late start (eGFR ≤5 ml/min per 1.73 m²). 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 m² 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.Despite the widespread use of chronic dialysis, there remains a lack of consensus about the optimal time at which renal replacement therapy should be initiated. Recommendations from the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) are generally used as a guideline, although they have been predominantly opinion-based (1). Initial NKF-DOQI guidelines suggested beginning dialysis at a GFR of ∼10.5 ml/min per 1.73 m², equivalent to a creatinine clearance of 9 to 13 ml/min (2). Updated NKF-DOQI guidelines in 2006 emphasized the need for a risk-benefit analysis when patients reach stage 5 chronic kidney disease or even earlier in certain circumstances (3). Although these guidelines suggest using clinical judgment, in practice, renal function at the time of dialysis initiation has been increasing over time (4). Early dialysis was believed to decrease mortality, hospitalization, and costs of treatment (5). However, early initiation creates lifestyle hardships, can be a limiting factor for employment and travel, and impacts the quality of life of patients and their families (6). Furthermore, multiple studies from the United States and Europe reported a lower level of renal function at dialysis initiation than recommended by the NKF-DOQI guidelines (7,8).Because randomized prospective controlled trials addressing this important practical point are lacking, the goal of this project was to study the mortality associated with early compared with late dialysis initiation based on retrospective data from the U.S. Renal Data System (USRDS).