Table 3:

Variation in hospital-specific observed-to-expected ratios for death or urgent readmission within 30 days and their associated rankings

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).