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Table 1 Comparison of characteristics between the training and validation sets

From: Development and validation of a risk prediction model for postoperative pneumonia in adult patients undergoing Stanford type A acute aortic dissection surgery: a case control study

Characteristic

Training set n = 328 (%)

Validation set n = 164 (%)

P value

Demographics

Age (years)

49.4 ± 11.2

51.2 ± 11.6

0.426

Male

254 (77.4)

118 (72.0)

0.181

Body mass index (kg/m2)

25.5 ± 3.8

25.1 ± 3.4

0.289

Smoking history

138 (42.1)

78 (47.6)

0.248

Drinking history

109 (33.2)

67 (40.9)

0.118

Underlying conditions

Hypertension

221 (67.4)

114 (69.5)

0.632

Diabetes mellitus

15 (4.6)

6 (3.7)

0.636

Chronic obstructive pulmonary disease

16 (4.9)

8 (4.9)

1.000

Cerebrovascular disease

53 (16.2)

35 (21.3)

0.157

Peripheral vascular disease

43 (13.1)

24 (14.6)

0.642

Renal insufficiency

118 (36.0)

55 (33.5)

0.593

Gastrointestinal tract disease

26 (7.9)

16 (9.8)

0.494

Atrial fibrillation

2 (0.6)

2 (1.2)

0.478

General surgery history

69 (21.0)

32 (19.5)

0.693

Heart surgery history

25 (7.6)

7 (4.3)

0.155

New York Heart Association class

  

0.405

 I

211 (64.3)

114 (69.5)

 

 II

85 (25.9)

41 (25.0)

 

 III

26 (7.9)

7 (4.3)

 

 IV

6 (1.8)

2 (1.2)

 

Pulmonary artery hypertension

9 (2.7)

5 (3.0)

0.848

Pericardial effusion

97 (29.6)

36 (22.0)

0.092

Left ventricular ejection fraction (%)

62 (60, 65)

62 (60, 65)

0.892

Laboratory values

White blood cell count (× 109/L)

10.4 (7.4, 12.6)

9.7 (7.5, 13.0)

0.713

Red blood cell count (× 1012/L)

4.2 (3.8, 4.6)

4.2 (3.8, 4.6)

0.484

Hemoglobin (g/l)

129 (113, 139)

127 (114, 140)

0.650

Platelet count (× 109/L)

160 (127, 208)

159 (122, 191)

0.174

Serum creatinine (μmol/L)

81.4 (65.9, 111.6)

78.1 (65.5, 112.8)

0.306

Serum albumin (g/L)

37.7 ± 4.4

37.6 ± 4.7

0.886

Operative variables

Cardiopulmonary bypass time (minutes)

211 (174, 257)

210 (175, 258)

0.924

Aortic cross clamp time (minutes)

118 (96, 147)

121 (96, 149)

0.380

Transfusion of red blood cells (units)

7.5 (6.0, 8.5)

7.0 (6.0, 9.0)

0.865