title: 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 p 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 (p = 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.
authors.affiliation: Department of Medicine, University of Maryland School of Medicine, Baltimore 21201-1595, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Fink
authors.forename: J F
authors.initials: JF
authors.lastname: Gardner
authors.forename: N C
authors.initials: NC
authors.lastname: Armistead
authors.forename: M S
authors.initials: MS
authors.lastname: Turner
authors.forename: P D
authors.initials: PD
authors.lastname: Light
mesh_terms: D001806:Blood Urea Nitrogen; D005260:Female; D006436:Hemodialysis Units, Hospital / Q000592:standards*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D008297:Male; D008873:Mid-Atlantic Region; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies