Table 2.
(a) Readmission risk among THA patients. ORs (CIs). (b) Readmission risk among TKA patients. ORs (CIs)
| PNP versus PUB (ref) | PFP versus PUB (ref) | |||||||
| Without IV | With IV | Without IV | With IV | |||||
| OR | CI | OR | CI | OR | CI | OR | CI | |
| (a) Readmission risk among THA patients. ORs (CIs) | ||||||||
| PNP | 0.568 | 0.506 to 0.637 | – | – | – | |||
| PNP (IV) | – | 0.674 | 0.527 to 0.861 | – | – | |||
| PFP | – | – | 0.46 | 0.278 to 0.762 | – | |||
| PFP (IV) | – | – | – | 0.701 | 0.090 to 5.444 | |||
| Male | 1.324 | 1.207 to 1.452 | 1.329 | 1.211 to 1.458 | 1.327 | 1.199 to 1.468 | 1.327 | 1.199 to 1.469 |
| Age group 18–49 years* | 0.761 | 0.611 to 0.947 | 0.763 | 0.613 to 0.950 | 0.793 | 0.627 to 1.004 | 0.793 | 0.627 to 1.003 |
| Age group 50–59 years | 0.672 | 0.570 to 0.791 | 0.674 | 0.572 to 0.793 | 0.675 | 0.564 to 0.807 | 0.674 | 0.563 to 0.806 |
| Age group 60–69 years | 0.799 | 0.713 to 0.895 | 0.799 | 0.713 to 0.895 | 0.813 | 0.717 to 0.921 | 0.813 | 0.717 to 0.921 |
| Age group 70–79 years | Ref | – | Ref | – | Ref | Ref | ||
| Age group ≥80 years | 1.562 | 1.386 to 1.761 | 1.561 | 1.386 to 1.759 | 1.527 | 1.337 to 1.745 | 1.532 | 1.337 to 1.755 |
| CCI | 1.094 | 1.042 to 1.148 | 1.093 | 1.042 to 1.147 | 1.096 | 1.039 to 1.155 | 1.096 | 1.040 to 1.156 |
| LOSPY | 1.013 | 1.006 to 1.020 | 1.013 | 1.006 to 1.020 | 1.013 | 1.005 to 1.020 | 1.013 | 1.005 to 1.020 |
| Fixed effects | RHA/year | RHA/year | RHA/year | RHA/year | ||||
| Per cent concordant | 61.3 | 59.8 | 59.4 | 59.3 | ||||
| AIC | 14 712.063 | 14 803.935 | 11 844.369 | 11 855.8 | ||||
| (b) Readmission risk among TKA patients. ORs (CIs) | ||||||||
| PNP | 0.580 | 0.508 to 0.662 | – | – | – | |||
| PNP (IV) | – | 0.894 | 0.656 to 1.216 | – | – | |||
| PFP | – | – | 0.576 | 0.379 to 0.875 | – | |||
| PFP (IV) | – | – | – | 1.935 | 0.399 to 9.395 | |||
| Male | 1.261 | 1.130 to 1.408 | 1.284 | 1.150 to 1.434 | 1.288 | 1.140 to 1.455 | 1.276 | 1.128 to 1.443 |
| Age group 18–49 years* | 1.082 | 0.809 to 1.447 | 1.093 | 0.818 to 1.461 | 1.082 | 0.786 to 1.489 | 1.077 | 0.783 to 1.483 |
| Age group 50–59 years | 0.959 | 0.809 to 1.136 | 0.961 | 0.811 to 1.139 | 0.967 | 0.801 to 1.166 | 0.949 | 0.785 to 1.147 |
| Age group 60–69 years | 0.851 | 0.745 to 0.971 | 0.845 | 0.740 to 0.964 | 0.858 | 0.741 to 0.994 | 0.847 | 0.730 to 0.982 |
| Age group 70–79 years | Ref | Ref | Ref | Ref | ||||
| Age group ≥80 years | 1.276 | 1.079 to 1.509 | 1.276 | 1.079 to 1.508 | 1.188 | 0.981 to 1.439 | 1.204 | 0.993 to 1.460 |
| CCI | 1.135 | 1.065 to 1.208 | 1.139 | 1.070 to 1.213 | 1.134 | 1.057 to 1.217 | 1.142 | 1.064 to 1.226 |
| LOSPY | 1.017 | 1.007 to 1.027 | 1.018 | 1.008 to 1.028 | 1.015 | 1.004 to 1.027 | 1.016 | 1.005 to 1.027 |
| Fixed effects | RHA/year | RHA/year | RHA/year | RHA/year | ||||
| Per cent concordant | 59.9 | 57.7 | 57.2 | 57.2 | ||||
| AIC | 10 007.277 | 10 071.436 | 7862.441 | 7864.188 | ||||
*Age was divided into five groups: patients aged 18–49 years, patients aged 50–59 years, and then 10-year interval groups until the last group (aged 80 years and above).
AIC, Akaike information criterion; CCI, Charlson Comorbidity Index; IV, instrumental variable; LOSPY, length of hospital stay in the previous year; PFP, private for-profit hospital; PNP, private non-profit hospital; PUB, public hospital; RHA, Regional Health Authorities; THA, total hip arthroplasty; TKA, total knee arthroplasty.