Table II.
Patient preoperative blood tests between normal and abnormal blood test groups.
| Variable | Normal postoperative | Abnormal postoperative | Total | p-value |
|---|---|---|---|---|
| Mean preoperative bloods (SD; range) | ||||
| Haemoglobin, g/dl | 137.7 (12.5; 96.0 to 183.0) | 131.5 (13.8; 85.0 to 177.0) | 136.7 (12.9; 85.0 to 183.0) | < 0.001 |
| Packed cell volume, l/l | 0.417 (0.033; 0.307 to 0.537) | 0.398 (0.038; 0.276 to 0.519) | 0.414 (0.035; 0.276 to 0.537) | < 0.001 |
| Platelets, 10*9 /l (SD, range) | 266.3 (68.2; 112.0 to 742.0) | 286.4 (72.2; 114.0 to 856.0) | 269.5 (69.2; 112.0 to 856.0) | < 0.001 |
| White blood cells, 10*9 /l (SD, range) | 6.9 (2.3; 2.4 to 69.7) | 7.1 (2.3; 2.5 to 19.6) | 7.0 (2.3; 2.4 to 69.7) | 0.252 |
| Sodium, mmol/l (SD, range) | 140.5 (2.2; 131.0 to 148.0) | 137.5 (3.7; 124.0 to 144.0) | 140.1 (2.7; 124.0 to 148.0) | < 0.001 |
| Potassium, mmol/l (SD, range) | 4.4 (0.3; 3.1 to 5.8) | 4.4 (0.5; 3.0 to 5.8) | 4.4 (0.4; 3.0 to 5.8) | 0.937 |
| Creatinine, umol/l (SD, range) | 78.4 (19.6; 38.0 to 221.0) | 75.9 (27.7; 36.0 to 436.0) | 78.0 (21.2; 36.0 to 436.0) | 0.025 |
| eGFR, 1.73 m2 (SD, range) | 77.0 (13.7; 21.0 to 90.0) | 75.8 (15.4; 10.0 to 90.0) | 76.8 (13.9; 10.0 to 90.0) | 0.100 |
| Ferritin, ug/l (SD, range) | 174.3 (167.1; 7.0 to 2,521.0) | 166.9 (142.6; 15.0 to 1,230.0) | 173.1 (163.3; 7.0 to 2,521.0) | 0.404 |
| Postoperative variables | ||||
| Mean length of stay, days (SD, range) | 3.6 (2.5; 1.0 to 43.0) | 5.1 (9.1; 1.0 to 184.0) | 3.8 (4.4; 1.0 to 184.0) | < 0.001 |
| Readmission, n (%) | 0.820 | |||
| Yes | 34 (1.5) | 6 (1.4) | 40 (1.5) | |
| No | 2,243 (98.5) | 438 (98.6) | 2,681 (98.5) | |
| Mean days to readmission (SD; range) | 77.6 (103.8, 1.0 to 363.0) | 46.5 (72.6, 9.0 to 194.0) | 72.9 (99.6, 1.0 to 363.0) | 0.488 |
| Reoperation, n (%) | 0.734 | |||
| Yes | 17 (0.7) | 4 (0.9) | 21 (0.8) | |
| No | 2,260 (99.3) | 440 (99.1) | 2,700 (99.2) | |
| AKI, n (%) | < 0.001 | |||
| Yes | 0 (0) | 20 (4.5) | 20 (0.7) | |
| No | 2,277 (100) | 424 (95.5) | 2,701 (99.3) | |
| Transfused, n (%) | < 0.001 | |||
| Yes | 0 (0) | 67 (15.1) | 67 (2.5) | |
| No | 2,277 (100) | 377 (84.9) | 2,654 (97.5) | |
| Mean units transfused (SD; range) | 1.7 (0.5; 1.0 to 3.0) | 1.7 (0.5; 1.0 to 3.0) | ||
| Mean estimated blood loss, ml (SD; range) | 94.3 (27.2; 43.6 to 189.5) | 94.3 (27.2; 43.6 to 189.5) | ||
| Mean change in blood test values following surgery (SD; range) | ||||
| Haemoglobin, g/dl | 16.6 (8.3; -12.0 to 49.0) | 19.4 (9.7; -9.0 to 56.0) | 17.1 (8.6; -12.0 to 56.0) | < 0.001 |
| Packed cell volume, l/l | 0.05 (0.03; -0.370 to 0.150) | 0.06 (0.03; -0.300 to 0.170) | 0.05 (0.03; -0.370 to 0.170) | < 0.001 |
| Platelets, 10*9 /l | 24.4 (34.6; -230.0 to 259.0) | 32.5 (38.9; -138.0 to 184.0) | 25.7 (35.5; -230.0 to 259.0) | < 0.001 |
| White blood cells, 10*9 /l | 5.7 (3.2; -19.8 to 4.4) | 5.2 (3.5; -18.5 to 4.1) | 5.6 (3.2; -19.8 to 4.4) | 0.003 |
| Sodium, mmol/l | 3.5 (2.5; -5.0 to 11.0) | 6.2 (3.8; -5.0 to 20.0) | 3.9 (2.9; -5.0 to 20.0) | < 0.001 |
| Potassium, mmol/l | 0.1 (0.4; -4.9 to 1.5) | 0.1 (0.5; -1.5 to 1.6) | 0.1 (0.4; -4.9 to 1.6) | 0.691 |
| Creatinine, umol/l | 0.6 (10.8; -55.0 to 68.0) | 1.5 (19.3; -223.0 to 46.0) | 0.3 (12.6; -223.0 to 68.0) | 0.002 |
| eGFR, 1.73 m2 | 0.3 (8.6; -45.0 to 32.0) | 0.9 (12.1; -36.0 to 72.0) | 0.1 (9.3; -45.0 to 72.0) | 0.017 |
AKI, acute kidney injury; eGFR, estimated glomerular filtration rate; SD, standard deviation.