Hemodialysis adequacy in Network 5: Disparity between states and the role of center effects

The purpose of this study was to determine whether an observed difference i n hemodialysis adequacy between states in Network 5 was due to variations i n patient characteristics and to what extent dialysis center effects played a role in the observed disparity between states. This was a retrospective observational study of 6,969 patients dialyzed at centers in Maryland and V irginia. There were 3,919 patients on hemodialysis at 89 facilities in Virg inia and 3,050 subjects dialyzed at 65 centers in Maryland. The mean urea r eduction ratio (URR) was higher in Virginia compared with Maryland (68.2 +/ - 0.1% v 66.0 +/- 0.2%, P < 0.0001, respectively), and there continued to b e a mean difference in URR of 1.8% between VA and MD (P < 0.0001) after adj usting for several covariates. The differences in URR between states varied depending on facility proprietary status, size as measured by number of st ations, and relationship to hospital (free-standing or hospital-based). Fur thermore, the center where a patient dialyzed, when treated as a fixed effe ct, accounted for 15% of the variance in URR, The mean difference of 1.8% i n URR between states persisted in a mixed-effects model that included all c ovariates along with adjusting for dialysis centers as a random effect, The disparity in dialysis adequacy between states in Network 5 could not be ac counted for by demographic characteristics, case mix factors, or a large ce nter effect observed in the region. Therefore, we conclude that underlying national reports on dialysis adequacy are heterogeneous results related to differences across regions such as states within a given Network. This diff erence between states is not explained by the strong center effect found on adequacy in this population of hemodialysis patients, (C) 1999 by the Nati onal Kidney Foundation, Inc.