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Table 7 Factors affecting blood transfusion/blood loss in TKA

From: Efficacy and cost-effectiveness of universal pre-operative iron studies in total hip and knee arthroplasty

Total knee arthroplasty data OR/estimate (95% CI) Comparison P value Global P value
Bivariate analysisa
 Previous iron transfusion 13 (3, 56)   0.0007
Multivariable analysis for outcome: blood transfusiona
 Late pre-operative haemoglobin 0.80 (0.70, 0.91)a   0.0010
Multivariable analysis for outcome: blood loss
 Type of anaesthesia    0.0111
  Spinal/GA vs GA −111.4 (−185.6, −37.4) 0.0032  
  Spinal vs GA −71.3 (−135.2, −7.5) 0.0286  
 Anticoagulants    <.0001
  0 vs 2b −274 (−417, −130) 0.0002  
  0 vs 3b −232.7 (−403.0, −62.5) 0.0074  
Multivariable analysis for outcome: haemoglobin drop
 BMI −0.02 (−0.04, 0.0)   0.0120
 Gender (male vs female) −0.35 (−0.56, −0.15)   0.0007
 Anticoagulants    0.0288
  0 vs 2b −0.67 (−1.26, −0.08) 0.0249  
  1 vs 2b −1.44 (−2.41, −0.48) 0.0034  
 Late pre-operative haemoglobin 0.02 (0.01, 0.03)   <.0001
  1. aBinary logistic regression – odds ratio (95% confidence interval); modelling the probability that blood transfusion = ‘Yes’
  2. bAnti coag (0 = Clexane, 1 = aspirin, 2 = warfarin, 3 = all others [rivaroxaban, apixaban])