Table 1 Comparison of baseline characteristics
| Â | Overall group | Low crowding group | Intermediate crowding group | High crowding group | P |
|---|---|---|---|---|---|
(number = 770) | (number = 276) | (number = 250) | (number = 244) | ||
Age (years) | 65 (55 to 73) | 64 (53 to 72) | 67 (56 to 73) | 65 (54 to 74) | 0.081 |
Gender (male) | 437 (56.8) | 161 (58.3) | 131 (52.4) | 145 (59.4) | 0.232 |
Comorbidities | Â | Â | Â | Â | Â |
 Hypertension | 244 (31.7) | 76 (27.5) | 82 (32.8) | 86 (35.2) | 0.152 |
 Diabetes | 165 (21.4) | 52 (18.8) | 56 (22.4) | 57 (23.4) | 0.411 |
 Cardiovascular disease | 79 (10.7) | 26 (9.4) | 27 (10.8) | 26 (10.7) | 0.847 |
 Chronic lung disease | 48 (6.2) | 17 (6.2) | 18 (7.2) | 13 (5.3) | 0.690 |
 Chronic renal disease | 35 (4.5) | 4 (1.4) | 22 (8.8)a | 9 (3.7) | <0.001 |
 Chronic hepatic disease | 67 (8.7) | 19 (6.9) | 21 (8.4) | 27 (11.1) | 0.235 |
 Metastatic solid cancer | 194 (25.2) | 65 (23.6) | 58 (23.3) | 71 (29.1) | 0.241 |
 Hematologic malignancy | 99 (12.9) | 36 (13.1) | 29 (11.6) | 34 (13.9) | 0.734 |
 Organ transplantation | 14 (1.8) | 6 (2.2) | 3 (1.2) | 5 (2.1) | 0.667 |
 Neutropenia (ANC <500 mm3) | 131 (17.0) | 48 (17.4) | 42 (16.8) | 41 (16.8) | 0.978 |
Nursing home resident | 29 (3.8) | 9 (3.7) | 9 (3.6) | 11 (4.5) | 0.741 |
Poor performance status | 35 (4.6) | 11(4.0) | 12 (4.8) | 12 (4.9) | 0.854 |
Suspected infection focus | Â | Â | Â | Â | 0.259 |
 Intra-abdominal infection | 288 (37.4) | 112 (40.6) | 92 (36.8) | 84 (34.4) |  |
 Pneumonia | 218 (28.3) | 77 (27.9) | 71 (28.4) | 70 (28.7) |  |
 Urinary tract infection | 115 (14.9) | 40 (14.5) | 44 (17.6) | 31 (12.7) |  |
 Others | 149 (19.3) | 47 (17.0) | 43 (17.2) | 59 (24.2) |  |
Initial vital signs | Â | Â | Â | Â | Â |
 Mean arterial pressure (mmHg) | 66 (58 to 80) | 66 (58 to 81) | 65 (57 to 78) | 67 (59 to 81) | 0.185 |
 Heart rate (per minute) | 112 (95 to 130) | 115 (96 to 135) | 109 (94 to 126) | 112 (95 to 130) | 0.065 |
 Respiratory rate (per minute) | 20 (20 to 24) | 20 (20 to 24) | 20 (20 to 24) | 20 (19 to 24) | 0.271 |
 Body temperature (°C) | 38.0 (36.8 to 38.9) | 38.3 (37.0 to 38.9) | 37.9 (36.7 to 38.8) | 37.9 (36.8 to 38.9) | 0.165 |
Initial presentation of cryptic shock | 288 (37.4) | 103 (37.2) | 95 (38.0) | 90 (36.9) | 0.967 |
Initial serum lactate (mmol/L) | 4.3 (2.5 to 5.7) | 4.4 (2.8 to 5.8) | 4.4 (2.4 to 5.7) | 4.2 (2.5 to 5.4) | 0.531 |
SOFA score | 7 (4 to 9) | 7(4 to 10) | 7(4 to 9) | 7(4 to 9) | 0.458 |
Mechanical ventilation | 87 (11.3) | 32 (11.6) | 28 (11.2) | 27 (11.1) | 0.980 |
Time period of initial presentation | Â | Â | Â | Â | Â |
 Night (10 PM to 7 AM) | 191 (24.8) | 122 (44.2) | 60 (24.0)a | 9 (3.7)ab | < 0.001 |
 Weekend | 227 (29.5) | 162 (58.7) | 58 (23.2)a | 7 (2.9)ab | < 0.001 |
Physician’s experience |  |  |  |  | 0.217 |
  ≤ 2nd year residents | 602 (78.2) | 212 (76.8) | 190 (76.0) | 200 (82.0) |  |
  ≥ 3rd year residents or | 168 (21.8) | 64 (23.2) | 60 (24.0) | 44 (18.0) |  |
 board-certified physicians |  |  |  |  |  |
Physician’s gender (male) | 381 (49.5) | 135 (48.9) | 114 (45.6) | 132 (54.1) | 0.163 |
Nurse’s experience |  |  |  |  | 0.115 |
 0 to about 2 years | 397 (51.6) | 152 (55.3) | 136 (54.4) | 109 (44.7) |  |
 3 to about 5 years | 215 (28.0) | 73 (26.6) | 67 (26.8) | 75 (30.7) |  |
 More than 5 years | 157 (20.4) | 50 (18.2) | 47 (18.8) | 60 (24.6) |  |
Use of EMS | 247 (32.2) | 88 (32.1) | 81 (32.4) | 78 (32.1) | 0.997 |
Study period | Â | Â | Â | Â | 0.221 |
 2008 to about 2009 | 291 (37.8) | 104 (37.7) | 104 (41.6) | 83 (34.0) |  |
 2010 to about 2012 | 479 (62.2) | 172 (62.3) | 146 (58.4) | 161 (66.0) |  |
Critical care zone at full capacity | 55 (7.1) | 9 (3.3) | 10 (4.0) | 36 (14.6) | < 0.001 |
ED occupancy rate (%) | 132 (110 to 162) | 100 (92 to 111) | 136 (126 to 142) | 172 (163 to 187) | Â |