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Table 2 Imbalance of patient characteristics before and after propensity weighting in the assessment of acute kidney injury

From: Association between acute kidney injury and norepinephrine use following cardiac surgery: a retrospective propensity score-weighted analysis

Variables

Before weighting

After weighting

No exposure to NE

(n = 3448)

Exposure to NE

(n = 1605)

SMD

No exposure to NE

(n = 3498)

Exposure to NE

(n = 1581)

SMD

Age (years)

68 [60–76]

70 [61,7]

0.120

69 [61, 76]

68 [60, 76]

< 0.001

Male gender

2407 (70)

1080 (67)

0.054

2429 (69)

1105 (70)

0.009

BMI (kg m−2)

27.48 [24.44–30.72]

26.83 [23.83–30.42]

0.017

27.53 [24.39, 30.76]

26.76 [23.72–30.26]

0.025

Hypertension

1925 (56)

890 (56)

0.008

1922 (55)

868 (55)

0.001

Coronary disease

385 (11)

213 (13)

0.064

404 (12)

189 (12)

0.012

Diabetes

690 (20)

294 (18)

0.043

672 (19)

304 (19)

< 0.001

Dyslipidemia

274 (8)

107 (7)

0.049

259.5 (7)

122 (8)

0.010

Chronic kidney disease

126 (4)

98 (6)

0.114

155.9 (5)

75 (5)

0.013

Peripheral vascular disease

188 (6)

76 (5)

0.033

206 (6)

74 (5)

0.055

Hemoglobin,

g dl−1

12.5 ± 0.5

12.2 ± 0.1

0.181

12.3 ± 0.7

12.3 ± 0.8

0.002

Platelet,

103 mm−3

148 ± 34

139 ± 35

0.111

146 ± 34

143 ± 36

0.004

Creatinine (µ mol l−1)

77 [64–94]

82 [67–105]

0.187

79 [65–98.09]

78 [65–97.34]

0.013

CPB time (min)

84 [56–118]

100 [67, 136]

0.336

88 [58–125]

91 [61–125]

0.032

Aortic clamp time (min)

57 [35–83]

64 [42–94]

0.111

59 [37–87]

60 [39–89]

0.004

Surgery type

      

 CABG

962 (28)

468 (29)

0.185

1000 (29)

461 (29)

0.012

 Valve surgery

1254 (36)

620 (39)

1285 (37)

576 (36)

 Combined surgery

336 (10)

212 (13)

369 (11)

166 (11)

 Others

896 (26)

305 (19)

845 (24)

379 (24)

SAPS II

34 [28–40]

40 [33–48]

0.595

35 [29–43]

36 [30–43]

0.026

Inotropes

0 (0)

128 (8)

0.306

0 (0)

87 (6)

0.226

  1. An absolute MSD < 10% was considered to support the assumption of a balance between the groups. SMD: standardized mean differences. Data are presented as medians [interquartile ranges] or as numbers (percentages). NE: norepinephrine, CABG: coronary bypass graft, CPB: coronary bypass, SAPS II: Simplified Acute Physiology Score. BMI, hypertension, and peripheral vascular disease were not selected for the propensity weighting as the P value for their association with acute kidney injury was over 20%