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. 2014 Sep;22(9):1241–1250. doi: 10.1016/j.joca.2014.07.006
Variable Competing risks model
Cox model (as in paper)
SHR (±95 CI) Significance HR (±95 CI) Significance
Age (linear, per year) 0.96 (0.96–0.97) <0.01 0.96 (0.96–0.97) <0.01
Gender (male) 0.85 (0.76–0.94) <0.01 0.86 (0.76–0.96) 0.01
ASA (per one grade increase) 1.07 (0.96–1.18) 0.22 1.06 (0.95–1.20) 0.30
BMI (per unit, n = 13,501) 1.01 (0.98–1.03) 0.59 1.01 (0.98–1.03) 0.59
Ethnic group – white Reference
un-defined 0.86 (0.74–1.01) 0.07 0.86 (0.72–1.02) 0.08
Mixed race 0.34 (0.05–2.42) 0.28 0.34 (0.05–2.24) 0.26
Asian 0.80 (0.52–1.24) 0.32 0.81 (0.52–1.25) 0.34
Black 1.02 (0.50–2.07) 0.96 1.02 (0.50–2.06) 0.96
Other 0.39 (0.10–1.57) 0.19 0.39 (0.09–1.61) 0.19
Unit type – NHS hospital Reference
Independent hospital 1.06 (0.88–1.29) 0.53 1.07 (0.87–1.30) 0.53
ISTC 1.40 (0.96–2.03) 0.08 1.43 (0.99–2.05) 0.05
Consultant performed 0.78 (0.67–0.91) <0.01 0.78 (0.67–0.91) <0.01
Mechanical thrombo-prophylaxis TEDS Reference
Foot pumps 0.97 (0.84–1.21) 0.68 0.98 (0.81–1.19) 0.82
Other 1.22 (0.74–1.99) 0.27 1.24 (0.77–2.01) 0.37
None 1.00 (0.86–1.17) 0.96 1.01 (0.83–1.22) 0.94
Chemical thrombo-prophylaxis Heparin/LMWH Reference
Aspirin 1.10 (0.94–1.29) 0.22 1.11 (0.90–1.37) 0.34
Warfarin 0.70 (0.34–1.50) 0.36 0.71 (0.35–1.44) 0.34
DTI 0.55 (0.30–1.00) 0.05 0.55 (0.30–1.01) 0.06
Other 0.80 (0.58–1.11) 0.18 0.81 (0.59–1.11) 0.19
None 1.21 (1.04–1.41) 0.02 1.22 (0.98–1.51) 0.08
Fixation 1.02 (0.83–1.25) 0.87 1.02 (0.79–1.31) 0.89
Charlson – No comorbidities Reference
Mild comorbidities 1.13 (0.97–1.31) 0.13 1.12 (0.96–1.30) 0.16
Moderate comorbidities 1.46 (1.04–2.05) 0.03 1.49 (1.04–2.12) 0.03
Severe comorbidities 1.26 (0.63–2.53) 0.51 1.40 (0.72–2.72) 0.33
IMD (per quintile) 0.96 (0.92–1.00) 0.04 0.96 (0.91–1.00) 0.07
Unit size (per ten cases) Up to 40 cases/yr 0.99 (0.99–1.00) <0.01 0.92 (0.86–0.97) 0.01
Above 40 cases/yr 1.00 (1.00–1.00) 0.13 0.99 (0.97–1.01) 0.32

Estimates from competing risks and Cox regression models for survival. SHR – Subhazard Ratio; TEDS – Thromboembolic deterrent stockings; LMWH – Low Molecular Weight Heparin; DTI – Direct Thrombin Inhibitor.