Unadjusted | | | |

facilities in total data set (*n* = 189) | 0.16 | (0.13, 0.19)^{a} | 18.9%^{a} |

facilities in reduced data set (*n* = 149) | 0.20 | (0.15, 0.23)^{a} | 23.6%^{a} |

facilities in reduced data set with random data | 0.00 | (0.00, 0.00) | 0% |

Covariates | | | |

case-mix covariates | — | — | 12.3%^{a} |

dialysis-specific covariates | — | — | 11.3%^{a} |

Adjusted for case-mix and dialysis covariates | | | |

all facilities in reduced data set | 0.14 | (0.11, 0.18)^{a} | 37.8%^{a} |

facilities by method and time of post-BUN measurement | | | |

sampling with slow flow method (*n* = 61) | 0.13 | (0.08, 0.20)^{a} | 40.5%^{a} |

sampling <1 min postdialysis (*n* = 31) | 0.10 | (0.04, 0.18)^{a} | 34.1%^{a} |

sampling >1 min postdialysis (*n* = 38) | 0.18 | (0.11, 0.28)^{a} | 39.7%^{a} |

unknown postdialysis sampling time (*n* = 19) | 0.08 | (0.03, 0.18)^{a} | 30.8%^{a} |