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Table 4 Survival. Association between overall survival and continuous or dichotomised preoperative variables, including Charlson Co-morbidity score, laboratory biomarkers and CPET-derived variables. Analysis was done using Cox proportional hazards regression analysis

From: Clinical covariates that improve surgical risk prediction and guide targeted prehabilitation: an exploratory, retrospective cohort study of major colorectal cancer surgery patients evaluated with preoperative cardiopulmonary exercise testing

Preoperative parameters Dichotomised reference level N Hazard ratio or (1/hazard ratio)a 95%CI P-value
A. Univariable Analysis
Charlson Co-morbidity Risk Index
  i. Continuous   82 1.03 0.81, 1.32 0.810
  ii. Dichotomised < 5 82 1.62 0.54, 4.84 0.380
Laboratory parameters
  i. Continuous
   • Haemoglobin (g/l)   58 0.93, a1.08 0.89, 0.98 0.001
   • White cell count (× 109/l)   58 1.29 1.08, 1.55 0.012
   • Neutrophils (× 109/l)   58 1.36 1.10, 1.67 0.010
   • Albumin (g/l)   34 0.89, a1.12 0.80, 1.00 0.050
   • Modified (neutrophil-albumin) Glasgow Prognostic Score   34 3.16 1.21, 8.27 0.024
  ii. Dichotomised Risk cut-point     
   • Haemoglobin (g/l) <110 58 0.232, a 4.31 0.06, 0.87 0.032
   • White Cell Count (× 109/l) > 11 58 4.40 0.91, 21.30 0.110
   • Neutrophils (× 109/l) > 7.5 58 6.79 1.68, 27.50 0.020
   • Platelets (× 109/l) > 350 58 2.98 0.74, 11.90 0.150
   • Albumin (g/l) < 35 34 0.22, a4.55 0.04, 1.12 0.051
  iii. Ratios
Neutrophil-lymphocyte ratio (NLR) > 4 58 1.57 0.42, 5.84 0.510
Platelet-lymphocyte ratio (PLR) > 160 58 0.92 0.23, 3.67 0.900
CPET-derived parameters
  i. Continuous
   • Peak VO2 (ml/kg/min)   82 0.91, a1.10 0.80, 1.04 0.150
   • Peak VO2 (ml/min/m2) (× 100)   82 0.65, a1.54 0.45, 0.94 0.012
   • VO2 @ AT (ml/kg/min)   82 0.89, a1.12 0.72, 1.10 0.250
   • Ve/VCO2 @ AT   82 1.09 1.02, 1.15 0.014
   • PETCO2 @ AT (mmHg)   82 0.89, a1.12 0.82, 0.96 0.004
  ii. Dichotomised Risk cut-point     
   • Peak VO2 (ml/kg/min) < 16 82 0.35, a 2.86 0.12, 1.00 0.049
   • Peak VO2 (ml/min/m2) < 710 82 0.13, a7.70 0.03, 0.56 0.001
   • VO2 @ AT (ml/kg/min) < 12 82 0.69, a1.45 0.23, 2.05 0.490
   • Ve/VCO2 @ AT > 35 82 6.12 2.13, 17.50 0.001
   • PETCO2 @ AT (mmHg) < 35 82 0.160, a6.25 0.05, 0.47 0.002
B. Bi-variable analysis
 • Haemoglobin (g/l)    0.94, a1.06 0.90, 0.99 0.017
 • Ve/VCO2 @ AT >35 10 2.60 0.63, 11.00 0.180
 • Peak VO2 (ml/min/m2) <710 42 0.18 0.04, 0.85 0.013
 • Ve/VCO2 @ AT > 35 13 a5.56, 3.70 1.30, 11.00 0.020
 • Peak VO2 (ml/min/m2) > 710 28 0.11, a9.09 0.01, 0.87 0.007
 • Neutrophils (× 109/l)    1.40 1.10, 1.70 0.008
  1. CPET, cardiopulmonary exercise testing; Peak VO2, maximum rate of oxygen consumption measured during incremental exercise; VO2 @ AT, oxygen uptake at anaerobic threshold; Ve/VCO2, minute ventilation relative to carbon dioxide elimination; PETCO2 @ AT, partial pressure of end tidal carbon dioxide at anaerobic threshold
  2. aInverse of hazard ratio to show directional change related to overall survival relative to other variables