Table 1 Characteristics of the study patients according to the occurrence of postoperative AKI
| Â | Overall | No AKI | AKI | Â |
|---|---|---|---|---|
Variables * | (n = 3314) | (n = 3091, 93.27%) | (n = 223, 6.72%) | P value |
Age, yrs | 67 (60, 73) | 66 (60, 73) | 70 (63, 75) |  < 0.001 |
Male sex | 1729 (52.2) | 1588 (51.4) | 141 (63.2) |  < 0.001 |
BMI, kg/m2 | 22.86 (20.43, 25.40) | 22.86 (20.44, 25.39) | 22.50 (20.25, 25.62) | 0.617 |
Medical history | ||||
 Hypertension | 1161 (35.0) | 1037 (33.5) | 124 (55.6) |  < 0.001 |
 Diabetes | 664 (20.0) | 595 (19.2) | 69 (30.9) |  < 0.001 |
 Coronary heart disease | 217 (6.5) | 175 (5.7) | 42 (18.8) |  < 0.001 |
 Stroke | 171 (5.2) | 150 (4.9) | 21 (9.4) | 0.005 |
 Congestive heart failure | 148 (4.5) | 102 (3.3) | 46 (20.6) |  < 0.001 |
 Ascites | 25 (0.8) | 21 (0.7) | 4 (1.8) | 0.145 |
 Use of RAAS inhibitors | 424 (12.8) | 365 (11.8) | 59 (26.5) |  < 0.001 |
Preoperative laboratory findings | ||||
 eGFR, mL min−1 1.73 m2 | 89.40 (74.53, 105.70) | 89.80 (75.50, 105.70) | 80.80 (61.55, 106.70) |  < 0.001 |
 aProteinuria (≥ 1 +) | 158 (4.8) | 125 (4.0) | 33 (14.8) |  < 0.001 |
 Haemoglobin, g l−1 | 124 .00(110.00, 136.00) | 125.00 (110.00, 137.00) | 117.00 (101.00, 131.50) |  < 0.001 |
 Serum albumin, g l−1 | 37.70 (34.70, 40.60) | 37.80 (34.80, 40.60) | 37.00 (33.65, 39.50) | 0.001 |
 NT-proBNP, pg ml−1 | 76.36 (39.86, 178.47) | 72.74 (38.84, 164.60) | 163.10 (77.75, 913.50) |  < 0.001 |
 LVEF, % | 66.00 (62.00, 70.80) | 66.00 (62.00, 71.00) | 61.00 (50.00, 67.15) |  < 0.001 |
Surgical characteristics | ||||
 Emergency surgery | 82 (2.5) | 66 (2.1) | 16 (7.2) |  < 0.001 |
 Type of surgery |  |  |  |  < 0.001 |
 General | 1330 (40.1) | 1214 (39.3) | 116 (52.0) |  |
 Orthopaedic | 1132 (34.2) | 1059 (34.3) | 73 (32.7) |  |
 Thoracic | 786 (23.7) | 757 (24.5) | 29 (13.0) |  |
 Gynaecological | 52 (1.6) | 49 (1.6) | 3 (1.3) |  |
 Others | 14 (0.4) | 12 (0.4) | 2 (0.9) |  |
 Surgery duration, hrs | 2.00 (2.00, 3.00) | 2.00 (2.00, 3.00) | 2.00 (2.00, 4.00) | 0.069 |
 Major surgery | 482 (14.5) | 438 (14.2) | 44 ( 19.7) | 0.030 |
Type of anaesthesia | ||||
 General | 2820 (85.1) | 2626(85.0) | 194 (87.0) | 0.466 |
ASA physical status | ||||
 I | 374 (11.3) | 365 (11.8) | 9 (4.0) |  |
 II | 2397 (72.3) | 2273 (73.5) | 124 (55.6) |  |
 III | 507 (15.3) | 429 (13.9) | 78 (35.0) |  |
 IV | 36 (1.1) | 24 (0.8) | 12 (5.4) |  |