Table 1.
Description of the baseline data of the study population (N = 11,285). Data are expressed as mean ± standard deviation or number (percentage). Preoperative chronic obstructive pulmonary disease (COPD) was defined according to clinical criteria (patients were considered to be affected by COPD if they were prescribed inhalation bronchodilators, corticosteroids or other drugs labeled for COPD therapy by a pneumologist or the family physician, even without obtaining confirmation from preoperative instrumental data) at the time of hospital admission.
| Variable | Training Set (7448 (66%) Cases) | Test Set (3837 (34%) Cases) |
|---|---|---|
| Age, yrs | 67.98 ± 14.00 | 67.59 ± 13.98 |
| Male sex, n (%) | 4394 (59%) | 2302 (60%) |
| BMI, kg/m2 | 25.45 ± 3.97 | 25.46 ± 3.00 |
| Preoperative EF, % | 56.23 ± 9.00 | 56.19 ± 9.99 |
| NYHA class > II, n (%) | (28.20%) | 1082 (28.20%) |
| Preoperative comorbidities | ||
| COPD, n (%) | 476 (6.39%) | 252 (6.56%) |
| Hypertension, n (%) | 3706 (49.75%) | 2003 (52.19%) |
| Type II Diabetes, n (%) | 779 (10.46%) | 426 (11.10%) |
| Preoperative creatinine, mg/dL | 0.98 ± 0.68 | 0.98 ± 0.66 |
| Chronic renal failure, n (%) | 1418 (19%) | 789 (20%) |
| Peripheral vasculopathy, n (%) | 1089 (14.63%) | 518 (13.50%) |
| Smoking habits, n (%) | 1,279,504 (17.17%) | 653 (17.01%) |
| Stroke, n (%) | (6.76%) | 279 (7.27%) |
| Timing of surgery | ||
| Emergency or urgency, n (%) | 63 (0.85%) | 32 (0.85%) |
| Planned, n (%) | 7385 (99.15%) | 3805 (99.15%) |
| Type of surgery | ||
| Valvular surgery, n (%) | 2944 (39.53%) | 1535 (39.99%) |
| Coronary surgery, n (%) | 991 (13.30%) | 476 (12.42%) |
| Ascending aorta aneurysm surgery, n (%) | 236 (3.17%) | 106 (2.77%) |
| Other surgical procedures, n (%) | 343 (4.60%) | 172 (4.48%) |
| Combined surgery (two or more procedures), n (%) | 2934 (39.40%) | 1548 (40.35%) |
BMI—body mass index; EF—ejection fraction; COPD—chronic obstructive pulmonary disease.