Table 1 Perioperative patient characteristics before and after matching

Age (days)

27, 7.7 to 100.2

58, 10 to 149

0.001

33.0, 7.0 to 89.5

0.83

Weight (kg)

3.4, 2.9 to 4.3

3.9, 3.2 to 5.4

< 0.001

3.3, 2.8 to 4.2

0.93

Surgery with cardiopulmonary bypass, n (%)

109 (90.8)

2560 (74.8)

< 0.001

110 (91.7)

0.80

Duration of cardiopulmonary bypass (min)

128.0, 99.5 to 177.0

109.0, 77.0 to 134.0

< 0.001

128.0, 90.0 to 165.0

0.64

Conventional ultrafiltration rate (mL kg^-1 h^-1)

93.3, 69.9 to 120.6

96.6, 66.9, 132.3

0.27

98.3, 87.2 to 127.3

0.40

Aristotle score^c

9.0, 7.5 to 10.8

8, 6 to 10

< 0.001

9.0, 7.3 to 10.8

0.99

Surgery with deep hypothermic circulatory arrest, n (%)

19 (15.8)

251 (7.3)

< 001

21 (17.5)

0.72

Re-sternotomy, n (%)

19 (15.8)

406 (11.9)

0.19

16 (13.3)

0.59

Requiring re-operation, n (%)

13 (10.8)

177 (5.2)

0.007

16 (13.3)

0.56

Re-operated within 48 hours, n (%)

3 (2.5)

18 (0.5)

0.03

2 (1.7)

0.66

Extracorporeal membrane oxygenation, n (%)

0

23 (0.7)

0

Requirement for delayed sternal closure, n (%)

56 (46.7)

331 (9.7)

< 0.001

57 (47.5)

0.85

Delay to sternal closure (days)

3, 2 to 4.2

4, 2 to 6

0.21

4, 3 to 7

0.08

Acute kidney injury requiring renal replacement therapy, n (%)

42 (35.0)

127 (3.7)

< 0.001

39 (32.5)

0.58

Requirement for renal replacement therapy on the day of surgery, n (%)

37 (30.8)

89 (2.6)

< 0.001

32 (26.7)

0.36

Duration of renal replacement therapy (days)

2, 1 to 4

3, 2 to 6

0.02

3, 2 to 7

0.09

The propensity score

0.07, 0.02 to 0.31

0.02, 0.01 to 0.03

0.07, 0.02 to 031