Table 1

 Interactions between case mix variables and hospital

Variable and year*Hospital specific odds ratio† (95% CI)Likelihood ratio test‡; P value
GEHMSHUHCUHN
Age (per 10 year age group)
Charlson index (per unit increase in Charlson index)
April 2005 to March 20061.07 (1.02 to 1.13)1.06 (1.00 to 1.12)0.99 (0.96 to 1.02)1.00 (0.96 to 1.03)χ2=13.10; P=0.01
April 2006 to March 20071.02 (0.98 to 1.07)1.01 (0.95 to 1.07)0.99 (0.95 to 1.02)0.92 (0.90 to 0.95)χ2=26.63; P<0.0001
April to October 20071.02 (0.95 to 1.09)0.96 (0.89 to 1.03)1.00 (0.96 to 1.05)0.99 (0.95 to 1.03)χ2=1.64; P=0.80
Emergency admission
April 2005 to March 20061.68 (1.21 to 2.34)1.76 (1.23 to 2.52)1.44 (1.22 to 1.71)1.79 (1.46 to 2.20)χ2=77.18; P<0.0001
April 2006 to March 20072.14 (1.39 to 3.29)4.55 (2.79 to 7.42)1.75 (1.46 to 2.11)3.09 (2.58 to 3.69)χ2=322.66; P<0.0001
April to October 20072.68 (1.45 to 4.96)1.85 (1.16 to 2.95)1.38 (1.10 to 1.74)1.45 (1.18 to 1.80)χ2=42.48; P<0.0001
April 2005 to March 20061.01 (1.00 to 1.01)1.00 (1.00 to 1.01)1.00 (1.00 to 1.01)1.00 (1.00 to 1.00)χ2=8.11; P=0.09
April 2006 to March 20071.00 (1.00 to 1.01)1.01 (1.00 to 1.01)1.00 (1.00 to 1.01)1.01 (1.00 to 1.01)χ2=25.00; P=0.0001
April to October 20071.00 (0.99 to 1.01)1.00 (0.99 to 1.01)1.00 (1.00 to 1.01)1.00 (0.99 to 1.00)χ2=3.01; P=0.56
Previous emergency admissions (per extra admission)
April 2005 to March 20061.02 (0.96 to 1.10)1.06 (0.98 to 1.15)1.01 (0.97 to 1.05)1.00 (0.95 to 1.05)χ2=3.20; P=0.53
April 2006 to March 20071.06 (0.99 to 1.14)1.10 (1.02 to 1.19)1.07 (1.03 to 1.12)0.99 (0.95 to 1.03)χ2=19.61; P=0.0006
April to October 20070.92 (0.84 to 1.02)1.05 (0.95 to 1.16)1.03 (0.97 to 1.09)1.00 (0.94 to 1.06)χ2=3.97; P=0.41
Sex
April 2005 to March 20061.10 (0.95 to 1.27)0.91 (0.78 to 1.06)1.02 (0.92 to 1.13)0.97 (0.87 to 1.09)χ2=3.23; P=0.52
April 2006 to March 20071.02 (0.88 to 1.19)0.89 (0.76 to 1.05)1.12 (1.01 to 1.25)1.03 (0.94 to 1.14)χ2=7.20; P=0.13
April to October 20070.99 (0.80 to 1.22)0.96 (0.78 to 1.19)1.07 (0.93 to 1.23)0.90 (0.79 to 1.03)χ2=3.27; P=0.51
Deprivation (per fifth)
April 2005 to March 20061.00 (0.95 to 1.05)1.02 (0.96 to 1.01)1.00 (0.97 to 1.04)1.01 (0.97 to 1.04)χ2=0.38; P=0.98
April 2006 to March 20071.00 (0.95 to 1.06)1.02 (0.96 to 1.09)1.02 (0.96 to 1.09)0.98 (0.95 to 1.02)χ2=3.01; P=0.56
April to October 20070.98 (0.91 to 1.06)0.94 (0.87 to 1.02)1.02 (0.97 to 1.07)1.05 (1.00 to 1.09)χ2=6.79; P=0.15

GEH=George Eliot Hospital; MSH=Mid Staffordshire Hospitals; UHC=University Hospitals Coventry and Warwickshire; UHN=University Hospital North Staffordshire.

*Year three, April to October 2007, is a part year because these were the most recent data available at the time of study.

†For relation between each case mix variable and mortality over and above that accounted for in Dr Foster Unit case mix adjustment equation.

‡Global test for systematic deviation from odds ratio=1 in any hospital; df=4.