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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