Table 1.
Comparison of Characteristics Between the Training and Validation Sets
| Characteristics |
Training set n=8960 (%) |
Validation set n=4480 (%) |
P value |
|---|---|---|---|
| Demographics | |||
| Men | 4822 (53.8) | 2420 (54.0) | 0.826 |
| Age, y | 51.51±13.13 | 51.79±13.19 | 0.241 |
| Body mass index, kg/m2 | 23.11±3.29 | 23.14±3.31 | 0.560 |
| Smoking history | 2395 (26.7) | 1239 (27.7) | 0.254 |
| Drinking history | 1812 (20.2) | 896 (20.0) | 0.761 |
| Underlying conditions | |||
| Hypertension | 2243 (25.0) | 1107 (24.7) | 0.683 |
| Diabetes | 682 (7.6) | 377 (8.4) | 0.103 |
| Chronic headache history | 966 (10.8) | 487 (10.9) | 0.875 |
| Chronic obstructive pulmonary disease | 1047 (11.7) | 495 (11.0) | 0.275 |
| Cerebrovascular disease | 1576 (17.6) | 774 (17.3) | 0.653 |
| Peripheral vascular disease | 1993 (22.2) | 965 (21.5) | 0.354 |
| Renal insufficiency | 652 (7.3) | 325 (7.3) | 0.963 |
| Gastrointestinal tract disease | 753 (8.4) | 349 (7.8) | 0.221 |
| Atrial fibrillation | 1718 (19.2) | 890 (19.9) | 0.339 |
| Cardiac surgery history | 626 (7.0) | 303 (6.8) | 0.631 |
| General surgery history | 2577 (28.8) | 1344 (30.0) | 0.136 |
| Pulmonary artery hypertension | 2610 (29.1) | 1308 (29.2) | 0.936 |
| Pericardial effusion | 1146 (12.8) | 603 (13.5) | 0.277 |
| NYHA class III or IV | 1509 (16.8) | 779 (17.4) | 0.426 |
| LVEF, % | 62 (57–67) | 62 (57–67) | 0.682 |
| Laboratory values | |||
| White blood cell count, ×109/L | 5.68 (4.73–6.79) | 5.64 (4.70–6.84) | 0.577 |
| RBC count, ×1012/L | 4.29 (3.93–4.66) | 4.30 (3.94–4.66) | 0.440 |
| Hemoglobin, g/L | 118 (106–129) | 130 (118–141) | 0.259 |
| Red cell distribution width, % | 14.1 (11.6–15.7) | 14.1 (11.6–15.7) | 0.182 |
| Serum creatinine, μmol/L | 60.5 (53.1–71.1) | 60.5 (53.2–71.4) | 0.522 |
| Serum albumin, g/L | 40.6 (38.3–42.9) | 40.7 (38.3–42.9) | 0.918 |
| Serum globulin, g/L | 24.2 (21.6–27.1) | 24.3 (21.5–27.1) | 0.551 |
| Operative variables | |||
| Surgical types | 0.649 | ||
| Isolated valve surgery | 5598 (62.4) | 2800 (62.5) | |
| Isolated coronary artery bypass grafting | 850 (9.5) | 400 (8.9) | |
| Mixed valve and coronary surgery | 992 (11.1) | 493 (11.0) | |
| Other types | 1520 (17.0) | 787 (17.6) | |
| Cardiopulmonary bypass time, min | 100 (77–130) | 99 (76–129) | 0.210 |
| Aortic cross clamp time, min | 67 (48–89) | 66 (47–87) | 0.190 |
| Transfusion of RBCs, units | 1 (0–3) | 1 (0–3) | 0.126 |
LVEF indicates left ventricular ejection fraction; NYHA, New York Heart Association; and RBC, red blood cell.