Table 6. Subgroup Analysis according to ER Arrival Time and Operation Start Time.
| ER arrival time | Operation start time | ||||||
|---|---|---|---|---|---|---|---|
| Day-time (n=1660) | Night-time (n=911) | p value | Day-time (n=1201) | Night-time (n=1370) | p value | ||
| Age (yr) | 49 (34–61) | 46 (32–57) | <0.001 | 47 (32–59) | 48 (34–60) | 0.027 | |
| Sex (male) | 794 (47.8) | 471 (51.7) | 0.060 | 593 (49.4) | 672 (49.1) | 0.870 | |
| Laboratory test | |||||||
| Hemoglobin <10 (g/dL) | 40 (2.4) | 31 (3.4) | 0.147 | 26 (2.2) | 45 (3.3) | 0.084 | |
| Abnormal WBC count (103/uL) | 1097 (66.5) | 694 (76.3) | <0.001 | 876 (73.3) | 915 (67.1) | 0.001 | |
| Neutrophil count >80 (%) | 737 (44.7) | 436 (48.0) | 0.112 | 565 (48.2) | 608 (44.6) | 0.176 | |
| C-reactive protein >1.0 (mg/dL) | 1159 (71.3) | 412 (45.5) | <0.001 | 677 (57.2) | 894 (66.4) | <0.001 | |
| Blood urea nitrogen >20 (mg/dL) | 183 (11.2) | 92 (10.2) | 0.442 | 122 (10.3) | 153 (11.3) | 0.404 | |
| Creatinine >1.0 (mg/dL) | 260 (15.9) | 118 (13.1) | 0.056 | 162 (13.6) | 216 (16.0) | 0.100 | |
| Albumin <3.0 (g/dL) | 65 (4.2) | 35 (4.2) | 0.991 | 45 (4.0) | 55 (4.3) | 0.710 | |
| Total bilirubin >2.0 (mg/dL) | 122 (7.4) | 37 (4.1) | 0.001 | 68 (5.7) | 91 (6.7) | 0.288 | |
| Vital sign | |||||||
| SBP <90 (mm Hg) | 23 (1.4) | 18 (2.0) | 0.253 | 21 (1.7) | 20 (1.5) | 0.560 | |
| Pulse rate >100 (bpm) | 200 (12.0) | 117 (12.6) | 0.558 | 157 (13.1) | 160 (11.7) | 0.284 | |
| Body temperature > 37.8 (°C) | 273 (16.4) | 151 (16.6) | 0.933 | 199 (16.6) | 225 (16.4) | 0.921 | |
| Diagnosis | <0.001 | <0.001 | |||||
| Appendicitis | 1422 (85.7) | 702 (77.1) | 959 (79.9) | 1165 (85.0) | |||
| Cholecystitis | 91 (5.5) | 102 (11.2) | 135 (11.2) | 58 (4.2) | |||
| Major emergency surgery | 147 (8.9) | 107 (11.7) | 107 (8.9) | 147 (10.7) | |||
| Number of residents on 24-h shift | 0.269 | 0.888 | |||||
| 1 | 321 (19.3) | 171 (18.8) | 225 (18.7) | 267 (19.5) | |||
| 2 | 1133 (68.3) | 645 (70.8) | 835 (69.5) | 943 (68.8) | |||
| 3 | 206 (12.4) | 95 (10.4) | 141 (11.7) | 160 (11.7) | |||
| AITR | 716 (43.0) | 402 (44.1) | 0.626 | 551 (45.9) | 567 (41.4) | 0.022 | |
| Surgery at night time | 1041 (62.7) | 329 (36.1) | <0.001 | ||||
| Night-time arrival at ER | 619 (51.5) | 1041 (76.0) | <0.001 | ||||
| Time from ER arrival to surgery (min) | 400 (322–515) | 599 (379–877) | <0.001 | 504 (348–841) | 411 (322–527) | <0.001 | |
| Length of hospital stay (day) | 4 (4–6) | 4 (4–6) | 0.616 | 4 (4–6) | 4 (4–6) | 0.021 | |
| Mortality | 36 (2.2) | 16 (1.8) | 0.477 | 19 (1.6) | 33 (2.4) | 0.137 | |
AITR, Act to Improve Training Conditions and the Status of Medical Residents; ER, emergency room; SBP, systolic blood pressure.
Data are presented as interquartile range or n (%).