Table 1.
Demographics and risk factors of derivation and validation cohorts
| Risk factors | Definition | Derivation cohort(n = 1208) N (%) |
Validation cohort (n = 540) N (%) | P value |
|---|---|---|---|---|
| Age > 65 years | Older than 65 years | 347 (28.7) | 200 (37) | < 0.001 |
| Female | 174 (14.4) | 83 (15.4) | 0.65 | |
| SCr > 2 mg/dl | Serum creatinine measured before surgery > 2 mg/dl | 13 (1.1) | 6 (1.1) | 1 |
| Chronic kidney disease | Documented past history or fulfilled the criteria of KDIGO 2012 | 5 (0.4) | 10 (1.9) | 0.006 |
| Extracardiac arteriopathy | Any one or more of the following: claudication, carotid occlusion or > 50% stenosis, previous or planned intervention on the abdominal aorta, and limb arteries or carotids | 98 (8.1) | 14 (2.6) | < 0.001 |
| Cerebrovascular accident | Documented past history of coma≥24 h or central nervous system dysfunction≥72 h | 42 (3.5) | 41 (7.6) | 0.003 |
| History of smoking | Prior history of smoking, regardless of whether the patients quit smoking | 988 (81.8) | 276 (51.1) | < 0.001 |
| Previous cardiac surgery | One or more previous major cardiac operation involving opening the pericardium | 45 (3.7) | 2 (0.4) | < 0.001 |
| COPD | Long-term use of bronchodilators or steroids for lung disease | 6 (0.5) | 8 (1.5) | 0.07 |
| Diabetes mellitus | Documented past history or fulfilled the criteria of WHO 1999 | 324 (26.8) | 218 (40.4) | < 0.001 |
| NYHA class III or IV | NYHA classification | 624 (51.7) | 237 (43.9) | 0.003 |
| CCS angina class = 4 | CCS class 4 angina (inability to perform any activity without angina or angina at rest) | 126 (10.4) | 7 (1.3) | < 0.001 |
| LVEF< 35% | Assessed by echocardiography (measured before surgery) | 85 (7) | 45 (8.3) | 0.39 |
| History of myocardial infarction | Documented history or ECG evidence including recent myocardial infarction (< 21 days) | 564 (46.7) | 278 (51.5) | 0.07 |
| Previous PCI | Documented history | 102 (8.4) | 78 (14.4) | < 0.001 |
| Non-elective surgery | Not routine admission for operation | 62 (5.1) | 11 (2.1) | 0.004 |
| Hypertension | Documented past history or SBP > 140 mmHg and/or DBP > 90 mmHg | 649 (53.7) | 308 (57) | 0.217 |
| On-pump surgery | With extracorporeal circulation | 648 (53.6) | 70 (13) | < 0.001 |
| Perioperative IABP | Intra-aortic balloon pump used before or after surgery | 14 (1.2) | 82 (15.2) | < 0.001 |
| Ventilation time > 24 h | Ventilation time longer than 24 h | 249 (20.6) | 94 (17.4) | 0.1352 |
| Perioperative transfusion | Transfusion before or after surgery | 140 (11.6) | 154 (28.5) | < 0.001 |
| AKI | Fulfilled the criteria of KDIGO 2012 | 90 (7.5) | 104 (19.3) | < 0.001 |
AKI acute kidney injury, CCS Canadian cardiovascular society, COPD chronic obstructive pulmonary disease, DBP diastolic blood pressure, ECG electrocardiography, LVEF left ventricular ejection fraction, NYHA New York heart association, PCI percutaneous coronary intervention, SBP systolic blood pressure, WHO world health organization