Table IV.
PROM models
| Variable | OKS model – continuous |
OKS model – binary |
Satisfaction |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Adjusted mean difference (±95 CI) | Sig. | Odds ratio (±95 CI) | Sig. | Odds ratio (±95 CI) | Sig. | ||||
| Age (per year) | 18–75 | 0.14 (0.09–0.20) | <0.001 | 0.96 (0.94–0.98) | <0.001 | 1.02 (1.01–1.03) | <0.001 | ||
| ≥75 | −0.18 (−0.63 to 0.07) | 0.162 | |||||||
| Gender | 0.19 (−0.63 to 1.02) | 0.650 | 1.06 (0.74–1.53) | 0.744 | 1.01 (0.86–1.18) | 0.924 | |||
| ASA grade | −0.53 (−1.35 to 0.29) | 0.206 | 1.00 (0.70–1.44) | 0.998 | 0.88 (0.77–1.02) | 0.088 | |||
| BMI | Normal weight | Reference | 1.00 (0.96–1.05) | 0.923 | 1.00 (0.98–1.02) | 0.979 | |||
| Underweight | 4.42 (−5.06 to 13.91) | 0.360 | |||||||
| Overweight | −0.03 (−1.47 to 1.42) | 0.972 | |||||||
| Obese | −1.04 (−2.50 to 0.41) | 0.160 | |||||||
| Ethnicity | White | Reference | Reference | Reference | |||||
| Un-defined | 0.24 (−1.08 to 1.57) | 0.717 | 0.90 (0.46–1.75) | 0.750 | 1.05 (0.84–1.32) | 0.654 | |||
| Mixed race | −0.60 (−7.33 to 6.12) | 0.860 | – | – | 0.65 (0.32–1.33) | 0.239 | |||
| Asian | −9.77 (−14.26 to −5.27) | <0.001 | 1.42 (0.43–4.64) | 0.564 | 0.41 (0.21–0.79) | 0.007 | |||
| Black | −10.79 (−19.19 to −2.75) | 0.009 | 3.65 (0.68–19.56) | 0.131 | 0.53 (0.29–0.99) | 0.048 | |||
| Other | −1.92 (−6.56 to 2.72) | 0.428 | – | – | 0.82 (0.47–1.44) | 0.494 | |||
| Unit type | Public Hospital | Reference | Reference | Reference | |||||
| Private hospital | 0.48 (−0.76 to 1.72) | 0.448 | 0.78 (0.43–1.41) | 0.412 | 1.16 (0.90–1.49) | 0.265 | |||
| ISTC | 1.09 (−0.91 to 3.09) | 0.286 | 0.26 (0.03–1.99) | 0.193 | 1.27 (0.91–1.78) | 0.154 | |||
| Consultant performed | 0.99 (−0.25 to 2.22) | 0.116 | 0.56 (0.35–0.91) | 0.018 | 1.40 (1.13–1.74) | 0.002 | |||
| Mechanical thrombo-prophylaxis | TEDs | Reference | Reference | Reference | |||||
| Foot pumps | 0.88 (−0.22 to 1.98) | 0.117 | 1.01 (0.65–1.58) | 0.951 | 1.10 (0.89–1.36) | 0.362 | |||
| Other | −1.29 (−7.22 to 4.63) | 0.668 | 0.74 (0.09–5.86) | 0.773 | 0.71 (0.35–1.46) | 0.358 | |||
| None | −1.48 (−3.37 to 0.41) | 0.125 | 1.31 (0.68–2.53) | 0.426 | 0.89 (0.67–1.18) | 0.423 | |||
| Chemical thrombo-prophylaxis | Heparin/LMWH | Reference | Reference | Reference | |||||
| Aspirin | −1.61 (−2.54 to 0.25) | 0.108 | 1.78 (1.02–3.12) | 0.043 | 0.75 (0.55–1.01) | 0.058 | |||
| Warfarin | −3.18 (−9.92 to 3.57) | 0.356 | 1.17 (0.23–6.01) | 0.854 | 1.01 (0.41–2.45) | 0.988 | |||
| DTI | 0.40 (−1.19 to 1.99) | 0.624 | 0.80 (0.36–1.77) | 0.584 | 0.82 (0.63–1.05) | 0.120 | |||
| Other | −0.44 (−1.69 to 0.81) | 0.486 | 0.77 (0.42–1.38) | 0.375 | 0.93 (0.74–1.16) | 0.509 | |||
| None | 0.93 (−1.04 to 2.90) | 0.356 | 0.83 (0.36–1.92) | 0.663 | 1.00 (0.72–1.37) | 0.985 | |||
| Implant fixation | −0.56 (−1.78 to 0.65) | 0.365 | 1.21 (0.67–2.18) | 0.530 | 0.81 (0.65–1.02) | 0.068 | |||
| Charlson co-morbidity index | None | Reference | Reference | Reference | |||||
| Mild | −0.71 (−1.79 to 0.37) | 0.198 | 1.01 (0.63–1.61) | 0.962 | 1.07 (0.88–1.29) | 0.498 | |||
| Moderate | 0.41 (−2.18 to 3.00) | 0.756 | 2.95 (1.23–7.05) | 0.015 | 1.21 (0.66–2.22) | 0.540 | |||
| Severe | 5.86 (−0.81 to 12.53) | 0.085 | 1.72 (0.20–15.01) | 0.624 | 2.19 (0.77–6.19) | 0.140 | |||
| IMD (Quintiles) | 0.93 (0.60–1.27) | <0.001 | 0.76 (0.66–0.88) | <0.001 | 1.07 (1.01–1.15) | 0.029 | |||
| Unit size (per 10 cases) | Up to 40 cases | 0.32 (−0.05 to 0.70) | 0.088 | 0.98 (0.95–1.02) | 0.354 | 1.01 (1.00–1.03) | 0.032 | ||
| Above 40 cases | 0.00 (−0.07 to 0.12 | 0.570 | |||||||
| Pre-operative OKS | 0.24 (0.18 to 0.30) | <0.001 | 1.10 (1.07–1.13) | <0.001 | 1.00 (0.99–1.01) | 0.807 | |||
| Pre-operative EQ5D anxiety/depression | None | Reference | Reference | Reference | |||||
| Moderate | −0.60 (−1.57 to 0.36) | 0.221 | 1.29 (0.86–1.94) | 0.220 | 0.97 (0.81–1.15) | 0.708 | |||
| Extreme | −3.32 (−6.16 to −0.47) | 0.023 | 1.63 (0.52–5.11) | 0.404 | 0.92 (0.55–1.54) | 0.752 | |||
| Self-reported health | −1.70 (−2.24 to −1.16) | <0.001 | 1.30 (1.03–1.65) | 0.027 | 0.58 (0.52–0.65) | <0.001 | |||
| Self-reported disability | −2.33 (−3.24 to 1.41) | <0.001 | 1.92 (1.30–2.86) | <0.001 | 0.82 (0.70–0.96) | 0.012 | |||
Adjusted mean differences are calculated in the multivariable linear regression models; positive figures demonstrate that the variable is associated with improved outcomes, negative figures demonstrate that the variable has a negative effect on post-operative OKS. TEDs – Thromboembolic Deterrent Stockings; LMWH – Low Molecular Weight Heparin; DTI – Direct Thrombin Inhibitor; OKS – Oxford Knee Score; EQ5D – EuroQol 5 Domain Score. BMI is categorised for the continuous PROM outcome as it predicts outcome in a non-linear fashion. Both satisfaction and the binary PROM outcome are predicted in a linear fashion and an overall Odds Ratio is given.