Table 1 Univariate analysis of perioperative factors and acute kidney injury for the whole cohort
Variables | Whole cohort (n = 2666) | No AKI (n = 1889) | AKIN 1 (n = 608) | AKIN 2 and 3 (n = 169) | p-value | |
|---|---|---|---|---|---|---|
Pre-operative | ||||||
Age (years) | 59.3 ± 10.5 | 58.0 ± 10.5 | 62.3 ± 9.6 | 62.4 ± 10.6 | <0.001 | |
Gender: male | 2143 (80.4) | 1534 (81.2) | 486 (79.9) | 123 (72.8) | 0.029 | |
Ethnicity | Chinese | 1912 (71.7) | 1390 (73.6) | 414 (68.1) | 108 (63.9) | <0.001 |
Malay | 425 (15.9) | 271 (14.3) | 126 (20.7) | 28 (16.6) | ||
Indian | 329 (12.3) | 228 (12.1) | 68 (11.2) | 33 (19.5) | ||
Body mass index (kg/m2) | 25.0 ± 4.1 | 24.9 ± 4.0 | 25.4 ± 4.3 | 24.9 ± 4.7 | 0.032 | |
Diabetes mellitus | 1205 (45.2) | 793 (42.0) | 294 (48.4) | 118 (69.8) | <0.001 | |
Hypertension | 1998 (74.9) | 1348 (71.4) | 503 (82.7) | 147 (87) | <0.001 | |
Myocardial infarction | 1559 (58.5) | 1072 (56.7) | 379 (62.3) | 108 (63.9) | 0.017 | |
Congestive cardiac failure | 435 (16.3) | 260 (13.8) | 130 (21.4) | 45 (26.6) | <0.001 | |
Renal impairment | 225 (8.4) | 90 (4.8) | 99 (16.3) | 36 (21.3) | <0.001 | |
Beta-blocker | 1998 (74.9) | 1377 (73.1) | 482 (79.3) | 139 (82.2) | 0.001 | |
ACE-inhibitor | 1300 (48.8) | 905 (48.0) | 306 (50.3) | 89 (52.7) | 0.365 | |
Calcium channel blocker | 521 (19.5) | 331 (17.6) | 144 (23.7) | 46 (27.2) | <0.001 | |
Statin | 2159 (81.0) | 1526 (81.0) | 494 (81.7) | 139 (82.2) | 0.881 | |
Diuretic | 480 (18.0) | 276 (14.6) | 149 (24.5) | 55 (32.5) | <0.001 | |
Ejection fraction (<30%) | 185 (6.9) | 110 (5.9) | 58 (9.6) | 17 (10.2) | 0.002 | |
Pre-operative creatinine (μmol/L) | 91.0 ± 42.7 | 85.7 ± 34.6 | 103.5 ± 51.5 | 98.7 ± 35.5 | <0.001 | |
Pre-operative eGFR (ml/min/1.73 m2) | 81.0 ± 21.6 | 84.8 ± 19.3 | 71.9 ± 23.9 | 71.7 ± 23.9 | <0.001 | |
Pre-operative haemoglobin (g/dL) | 13.5 ± 1.7 | 13.8 ± 1.6 | 13.1 ± 1.8 | 12.7 ± 1.8 | <0.001 | |
EuroSCORE logistic | 3.6 ± 4.6 | 3.1 ± 3.7 | 4.8 ± 6.0 | 4.9 ± 6.2 | <0.001 | |
Surgical variables | ||||||
Coronary artery bypass graft surgery | 2191 (82.2) | 1546 (82.2) | 506 (83.4) | 139 (82.2) | 0.802 | |
Valvular surgery | 622 (23.3) | 433 (22.9) | 148 (24.3) | 41 (24.3) | 0.733 | |
Cardiopulmonary bypass | 2578 (96.7) | 1820 (96.3) | 595 (97.9) | 163 (96.4) | 0.188 | |
IABP | 249 (9.3) | 130 (6.9) | 89 (14.7) | 30 (17.9) | <0.001 | |
Cardiopulmonary bypass time (min) | 113.5 ± 49.0 | 107.0 ± 43.4 | 125.7 ± 56.2 | 137.3 ± 64.7 | <0.001 | |
Aortic cross clamp time (min) | 67.2 ± 36.4 | 63.5 ± 32.8 | 74.1 ± 42.5 | 79.5 ± 46.0 | <0.001 | |
Inotrope use | 1652 (62.0) | 1120 (59.9) | 409 (67.7) | 123 (72.8) | <0.001 | |
Haemodilution | ||||||
Prebypass haematocrit (%) | 37.8 ± 4.9 | 38.3 ± 4.6 | 36.9 ± 5.3 | 35.8 ± 4.8 | <0.001 | |
Lowest haematocrit during bypass (%) | 24.4 ± 3.9 | 24.9 ± 3.9 | 23.4 ± 3.7 | 22.3 ± 3.8 | <0.001 | |
RBC transfusion | 746 (28.0) | 426 (22.6) | 238 (39.1) | 82 (48.5) | <0.001 | |
Intensive care unit variables | ||||||
Inotrope use | 1228 (46.1) | 780 (41.3) | 336 (55.4) | 112 (66.3) | <0.001 | |
New need for dialysis | 59 (2.2) | 12 (0.6) | 21 (3.5) | 26 (15.4) | <0.001 | |
Lowest haemoglobin in 1st 24 h (g/dL) | 9.7 ± 1.6 | 9.9 ± 1.5 | 9.2 ± 1.4 | 8.8 ± 1.4 | <0.001 | |
RBC transfusion | 1010 (37.9) | 608 (32.2) | 303 (49.9) | 99 (58.6) | <0.001 | |
Total length of hospitalization (days) | 11.0 ± 10.6 | 9.2 ± 5.6 | 13.2 ± 9.6 | 22.0 ± 30.2 | <0.001 | |
Outcomes | ||||||
End-stage renal disease | 24 (0.9) | 6 (0.3) | 12 (2.0) | 6 (3.6) | <0.001 | |
5-year mortality | 128 (4.8) | 68 (3.6) | 41 (6.7) | 19 (11.2) | <0.001 | |