Table 3 Risk factors for RBC transfusion (logistic regression stratified by centre, stepwise backward elimination)

Baseline characteristics

  SAPS II (per point)

1.06

1.03–1.08

 < 0.001

1.04

1.02–1.06

0.001

  Age (per year)

1.02

1–1.04

0.031

  Sex (male)

0.28

0.19–0.43

 < 0.001

0.23

0.14–0.39

 < 0.001

  BMI (per kg m⁻²)

0.95

0.91–1

0.031

0.94

0.89–0.99

0.016

Comorbidities

  ASA score (per class)

1.8

1.06–3.05

0.029

  Smoking

0.76

0.51–1.13

0.18

  Hypertension

1.48

0.97–2.24

0.066

1.53

0.94–2.49

0.09

  Dyslipidaemia

0.93

0.63–1.38

0.73

  Arteritis

1.57

0.83–2.96

0.16

  Angina

0.89

0.58–1.36

0.59

  CRF

1.98

1.15–3.41

0.014

  Obstructive lung disease

1.29

0.72–2.31

0.40

  Diabetes

0.88

0.53–1.46

0.62

  Atrial fibrillation

1.49

0.84–2.64

0.17

  NYHA class (per class)

1.63

1.22–2.18

 < 0.001

1.34

0.97–1.87

0.079

  LVEF (per %)

0.98

0.96–1

0.014

0.97

0.95–0.99

0.005

  Pulmonary hypertension

1.74

1–3.03

0.049

  Active antiplatelet therapy

1.13

0.77–1.68

0.53

Surgery characteristics

  Urgent surgery (vs elective)

1.76

0.97–3.2

0.065

  Reoperation

4.85

1.6–14.75

0.005

7.26

1.99–26.39

0.003

  Type of surgery

  Isolated valve

REF

REF

REF

REF

REF

REF

  Coronary bypass

0.91

0.58–1.44

0.69

1.46

0.85–2.51

0.168

  Combined surgery

1.80

1.04–3.13

0.036

2.66

1.40–5.06

0.003

  Others

2.26

0.93–5.31

0.062

2.64

0.99–7.04

0.053

Biological status^a

  Serum ferritin < 100 ng ml⁻¹

0.86

0.55–1.35

0.51

0.70

0.42–1.16

0.17

  Serum ferritin 100–300 ng ml⁻¹ and Tsat < 20%

1.52

0.99–2.34

0.058

1.11

0.67–1.84

0.69

  Iron deficiency

1.20

0.81–1.78

0.37

0.85

0.53–1.36

0.49

  Anaemia

3.96

2.41–6.51

 < 0.001

4.16

2.34–7.35

 < 0.001