Table 2.
Univariate analysis of possible risk factors for POP after elective cardiac surgery in the training set.
| Characteristic | Without POP | With POP | χ2/Z/t | P -value |
|---|---|---|---|---|
| n = 8,758 (%) | n = 608 (%) | |||
| Demographics | ||||
| Age (years) | 51.01 ± 13.15 | 59.60 ± 11.22 | 18.030 | <0.001 |
| Male | 4,700 (53.7) | 394 (64.8) | 28.428 | <0.001 |
| Body mass index (kg/m2) | 23.11 ± 3.28 | 23.54 ± 3.53 | 2.886 | 0.004 |
| Smoking history | 2,294 (26.2) | 258 (42.4) | 75.650 | <0.001 |
| Drinking history | 1,742 (19.9) | 146 (24.0) | 6.004 | 0.014 |
| Underlying conditions | ||||
| Hypertension | 2,057 (23.5) | 281 (46.2) | 156.814 | <0.001 |
| Diabetes mellitus | 596 (6.8) | 118 (19.4) | 128.225 | <0.001 |
| Chronic obstructive pulmonary disease | 915 (10.4) | 140 (23.0) | 89.997 | <0.001 |
| Cerebrovascular disease | 1,474 (16.8) | 160 (26.3) | 35.517 | <0.001 |
| Peripheral vascular disease | 1,857 (21.2) | 191 (31.4) | 34.696 | <0.001 |
| Renal insufficiency | 554 (6.3) | 127 (20.9) | 178.821 | <0.001 |
| Gastrointestinal tract disease | 717 (8.2) | 51 (8.4) | 0.031 | 0.861 |
| Atrial fibrillation | 1,663 (19.0) | 139 (22.9) | 5.490 | 0.019 |
| General surgery history | 2,541 (29.0) | 212 (34.9) | 9.391 | 0.002 |
| Cardiac surgery history | 540 (6.2) | 100 (16.4) | 94.403 | <0.001 |
| New York Heart Association class III-IV | 1,381 (15.8) | 185 (30.4) | 87.740 | <0.001 |
| Pulmonary artery hypertension | 2,521 (28.8) | 195 (32.1) | 2.984 | 0.084 |
| Pericardial effusion | 1,098 (12.5) | 105 (17.3) | 11.375 | 0.001 |
| Left ventricular ejection fraction (%) | 62 (57, 67) | 60 (55, 65) | 11.102 | <0.001 |
| Laboratory values | ||||
| White blood cell count (× 109/L) | 5.65 (4.71, 6.80) | 5.78 (4.80, 6.92) | 0.775 | 0.083 |
| Red blood cell count (× 1012/L) | 4.31 (3.96, 4.67) | 4.16 (3.76, 4.51) | 0.574 | <0.001 |
| Hemoglobin (g/l) | 130 (118, 141) | 127 (114, 140) | 0.260 | <0.001 |
| Serum creatinine (μmol/L) | 70.8 (60.2, 83.3) | 79.6 (65.3, 95.0) | 6.781 | <0.001 |
| Serum albumin (g/L) | 40.67 ± 3.78 | 39.43 ± 3.96 | 3.191 | <0.001 |
| Serum globulin (g/L) | 24.61 ± 4.35 | 25.15 ± 4.84 | 2.691 | 0.007 |
| Operative variables | ||||
| Cardiopulmonary bypass time (min) | 98 (76, 127) | 121 (95, 154) | 19.953 | <0.001 |
| Aortic cross clamp time (min) | 66 (47, 87) | 78 (59, 101) | 15.107 | <0.001 |
| Intraoperative transfusion of RBC (units) | 1 (0, 2.5) | 4 (1.5, 7) | 17.825 | <0.001 |
POP, postoperative pneumonia; RBC, red blood cell.