TABLE 1.
Summary of Predictor Variables by Presence of Outcome
| 30-d Mortality | ICU Stay >24 h | ||||||
| Variable | No (n = 90,246) | Yes (n = 539) | P Value | No (n = 89,521) | Yes (n = 1264) | P Value | % Missing |
| Patient demographics | |||||||
| Age (yrs) | 54 (38–65) | 71 (60–79) | <0.001 | 54 (38–65) | 65 (54–74) | <0.001 | 0% |
| Male sex | 41,767 (46%) | 310 (58%) | <0.001 | 41,292 (46%) | 785 (62%) | <0.001 | 0% |
| Ethnicity | 0.02 | 0.95 | 0% | ||||
| Chinese | 64,465 (71%) | 396 (73%) | 63,949 (71%) | 912 (72%) | |||
| Malay | 8914 (10%) | 65 (12%) | 8858 (10%) | 121 (10%) | |||
| Indian | 7969 (9%) | 43 (8%) | 7904 (9%) | 108 (9%) | |||
| Others | 8892 (10%) | 35 (6%) | 8804 (10%) | 123 (10%) | |||
| Height (cm) | 161 (155–168) | 160 (152–166) | <0.001 | 161 (155–168) | 161 (155–167) | 0.47 | 18% |
| Weight (kg) | 64 (55–74) | 58 (48–69) | <0.001 | 64 (55–74) | 62 (53–72) | <0.001 | 15% |
| BMI (kg/m2) | 25 (22–28) | 23 (20–27) | <0.001 | 25 (22–28) | 24 (21–27) | <0.001 | 18% |
| Comorbidities | |||||||
| CVA | 1501 (2%) | 42 (13%) | <0.001 | 1488 (2%) | 55 (7%) | <0.001 | 31% |
| IHD | 4119 (7%) | 126 (39%) | <0.001 | 4054 (7%) | 191 (24%) | <0.001 | 31% |
| CHF | 752 (1%) | 35 (10%) | <0.001 | 727 (1%) | 60 (7%) | <0.001 | 29% |
| DM on insulin | 1964 (3%) | 39 (12%) | <0.001 | 1945 (3%) | 58 (7%) | <0.001 | 30% |
| CKD | <0.001 | <0.001 | 12% | ||||
| Grade 1 | 47,805 (60%) | 143 (27%) | 47,497 (60%) | 451 (38%) | |||
| Grade 2 | 23,532 (30%) | 103 (20%) | 23,342 (30%) | 293 (25%) | |||
| Grade 3 | 5007 (6%) | 107 (20%) | 4884 (6%) | 230 (20%) | |||
| Grade 4 | 1116 (1%) | 83 (16%) | 1083 (1%) | 116 (10%) | |||
| Grade 5 | 1968 (2%) | 91 (17%) | 1970 (3%) | 89 (8%) | |||
| ASA-PS class | <0.001 | <0.001 | 5% | ||||
| I | 22,047 (26%) | 0 (0%) | 22,009 (26%) | 38 (3%) | |||
| II | 49,362 (58%) | 73 (16%) | 49,105 (58%) | 330 (29%) | |||
| III | 13,171 (15%) | 234 (51%) | 12,890 (15%) | 515 (45%) | |||
| IV–VI | 926 (1%) | 153 (33%) | 818 (1%) | 261 (23%) | |||
| Laboratory tests | |||||||
| Full blood count | |||||||
| Hemoglobin (g/dL) | 13 (12–15) | 11 (9–12) | <0.001 | 13 (12–15) | 12 (10–14) | <0.001 | 5% |
| MCV (fL) | 89 (85–92) | 90 (85–94) | 0.002 | 89 (85–92) | 89 (85–92) | 0.72 | 8% |
| RDW (%) | 13 (13–14) | 15 (14–17) | <0.001 | 13 (13–14) | 14 (13–16) | <0.001 | 8% |
| Hematocrit (%) | 40 (37–43) | 32 (28–37) | <0.001 | 40 (37–43) | 36 (31–41) | <0.001 | 8% |
| Platelet (x109/L) | 261 (219–313) | 229 (158–321) | <0.001 | 261 (219–313) | 244 (184–321) | <0.001 | 8% |
| aPTT (s) | 28 (26–30) | 31 (28–36) | <0.001 | 28 (26–30) | 29 (27–32) | <0.001 | 43% |
| PT (s) | 10 (10–11) | 12 (11–13) | <0.001 | 10 (10–11) | 11 (10–12) | <0.001 | 43% |
| Renal panel | |||||||
| Creatinine (umol/L) | 70 (57–86) | 109 (67–233) | <0.001 | 70 (57–86) | 86 (63–133) | <0.001 | 13% |
| eGFR (mL/min/1.73 m2) | 96 (79–114) | 54 (21–95) | <0.001 | 96 (79–114) | 77 (45–108) | <0.001 | 12% |
| Surgery details | |||||||
| Surgical risk | <0.001 | 0% | |||||
| Low | 47,901 (53%) | 148 (27%) | 47,847 (53%) | 202 (16%) | |||
| Moderate | 38,712 (43%) | 302 (56%) | 38,369 (43%) | 645 (51%) | |||
| High | 3633 (4%) | 89 (17%) | 3305 (4%) | 417 (33%) | |||
| Priority of surgery | <0.001 | <0.001 | 0% | ||||
| Elective | 72,148 (80%) | 183 (34%) | 71,655 (80%) | 676 (53%) | |||
| Emergency | 18,098 (20%) | 356 (66%) | 17,866 (20%) | 588 (47%) | |||
| Anesthesia type | 0.30 | <0.001 | 0% | ||||
| GA | 75,997 (84%) | 445 (83%) | 75,234 (84%) | 14,287 (96%) | |||
| RA | 14,249 (16%) | 94 (17%) | 1208 (1%) | 56 (4%) | |||
| No. of preoperative blood transfusions within 30 d | 0 (0–0) | 0 (0–0) | <0.001 | 0 (0–0) | 0 (0–1) | <0.001 | 0% |
For continuous variables, data is presented in medians and interquartile ranges. Mann–Whitney U test was used to test for differences.
For categorical variables, data is presented in frequencies and percentages. Chi square test was used to test for association.
aPTT indicates activated partial thromboplastin time; CHF, congestive heart failure; CVA, cerebrovascular accident; DM, diabetes mellitus; eGFR, estimated glomerular filtration rate; GA, general anesthesia; IHD, ischemic heart disease; MCV, mean corpuscular volume; PT, prothrombin time; RA, regional anesthesia.