Variation | Standardized ranges^{*} for observed-to-expected ratios (%) | Hospital rankings based on observed-to-expected ratios^{†} | ||||||
---|---|---|---|---|---|---|---|---|

Mean ± SD | Median (IQR) | Minimum | Maximum | Mean ± SD | Median (IQR) | Minimum | Maximum | |

Among measures within specific years | ||||||||

2005 | 32.5 ± 22.8 | 28 (18–42) | 7 | 232 | 43.3 ± 30.0 | 35 (20–61) | 0 | 143 |

2006 | 30.0 ± 18.7 | 29 (14–44) | 2 | 96 | 52.5 ± 32.9 | 49 (26–74) | 0 | 136 |

2007 | 31.8 ± 23.4 | 28 (14–41) | 2 | 157 | 54.4 ± 33.3 | 48 (30–75) | 3 | 159 |

2008 | 30.5 ± 18.7 | 28 (15–42) | 3 | 80 | 50.8 ± 32.0 | 45.5 (28–68) | 2 | 145 |

2009 | 31.9 ± 22.8 | 28 (17–41) | 4 | 212 | 49.5 ± 31.8 | 42.5 (26–70) | 0 | 151 |

2010 | 32.0 ± 23.8 | 27 (15–42) | 1 | 141 | 47.9 ± 32.8 | 43 (23–68) | 1 | 151 |

All years | 31.5 ± 21.8 | 28 (16–42) | 1 | 232 | 47.4 ± 32.2 | 43.5 (23–66) | 2 | 148 |

Among years within specific measures | ||||||||

Age-, sex-adjusted, all admissions | 27.5 ± 19.7 | 22 (15–35) | 4 | 154 | 45.2 ± 31.4 | 38 (22–62) | 1 | 155 |

Age-, sex-adjusted, single admission/patient | 49.8 ± 35.3 | 43 (26–66) | 8 | 273 | 61.0 ± 38.7 | 51.5 (31–81) | 1 | 161 |

Complete adjustment, all admissions | 26.0 ± 18.4 | 21 (14–33) | 3 | 131 | 62.8 ± 37.0 | 57 (34–87) | 4 | 161 |

Complete adjustment, single admission/patient | 47.8 ± 37.0 | 38 (24–59) | 7 | 288 | 75.8 ± 40.2 | 72 (44–103) | 3 | 161 |

Note: IQR = interquartile range, SD = standard deviation.

↵* Range in observed-to-expected ratios for readmission within each hospital as a percentage of the overall readmission ratio for that hospital. The overall ratio was calculated using a fixed-effects model that weighted observations by each ratio’s variance, which were calculated using Byar’s approximation.14

↵† The maximum range in rankings is 162 (i.e., the total number of hospitals included in the study).