Within-center correlation in dialysis adequacy^☆

Abstract 

The purpose of this study was to determine whether patients with end stage renal disease treated with hemodialysis were correlated in dialysis adequacy within facilities. This was a retrospective analysis of dialysis adequacy based on urea reduction ratio (URR) values from 6969 patients dialyzed at 154 facilities. The within-center correlation was quantified using the between-center variation and the parameter ρ that was derived using ANOVA tables and mixed effects models. The variation in center means for URR was wider than expected for independent observations (52.9–76.1 versus 60.7–73.8, respectively). Furthermore, there was a significant within-center correlation in URR values across all facilities (ρ = 0.136, P < 0.0001), which persisted after adjusting for patient specific covariates, facility characteristics, and state. In conclusion, there was a substantial within-center correlation in dialysis adequacy that reflected important center effects on the outcome of ESRD patients.

Keywords:  Dialysis adequacy, Intraclass correlation, Center effects

• ☆ The conclusions and opinions expressed and methods used herein are those of the author. They do not necessarily reflect HCFA policy. The authors assume full responsibility for the accuracy and completeness of the ideas presented. Ideas and contributions to the author concerning experience in engaging with issues presented are welcomed.