Table 1.
Characteristics of patients in the training, validation and test sets
| Total | Training set | Validation set | Test set | |
|---|---|---|---|---|
| Total | 73,905 | 43,576 | 10,894 | 19,435 |
| Age, years | 73 (60–82) | 73 (59–81) | 73 (60–82) | 74 (60–82) |
| Sex, male | 46,720 (63.2) | 27,524 (63.2) | 6846 (62.8) | 12,350 (63.5) |
| Diabetes mellitus | 16,850 (22.8) | 9765 (22.4) | 2442 (22.4) | 4643 (23.9) |
| Hypertension | 25,804 (34.9) | 14,924 (34.2) | 3725 (34.2) | 7155 (36.8) |
| Heart disease | 13,147 (17.8) | 7478 (17.2) | 1869 (17.2) | 3800 (19.6) |
| Time of day, daytime (6AM-6PM) | 46,694 (63.2) | 27,489 (63.1) | 6815 (62.6) | 12,390 (63.8) |
| Region, urban | 63,892 (86.5) | 37,697 (86.5) | 9407 (86.4) | 16,788 (86.4) |
| ECPR-capable district | 38,615 (52.2) | 22,803 (52.3) | 5723 (52.5) | 10,089 (51.9) |
| Presumed cardiac cause | 70,288 (95.1) | 41,408 (95.0) | 10,379 (95.3) | 18,501 (95.2) |
| Place of arrest | ||||
| Public | 12,390 (16.8) | 7330 (16.8) | 1793 (16.5) | 3267 (16.8) |
| Non-public | 61,507 (83.2) | 36,239 (83.2) | 9100 (83.5) | 16,168 (83.2) |
| Missing | 8 (0.0) | 7 (0.0) | 1 (0.0) | 0 (0.0) |
| Witnessed status | ||||
| EMS witnessed | 1754 (2.4) | 917 (2.1) | 218 (2.0) | 619 (3.2) |
| Bystander witnessed | 44,075 (59.6) | 26,512 (60.8) | 6604 (60.6) | 10,959 (56.4) |
| Unwitnessed | 27,727 (37.5) | 15,892 (36.5) | 4015 (36.9) | 7820 (40.2) |
| Missing | 349 (0.5) | 255 (0.6) | 57 (0.5) | 37 (0.2) |
| Bystander CPR | ||||
| Dispatcher-assisted | 33,569 (45.4) | 19,506 (44.8) | 4818 (44.2) | 9245 (47.6) |
| Unassisted | 15,437 (20.9) | 9295 (21.3) | 2343 (21.5) | 3799 (19.5) |
| No CPR | 23,764 (32.2) | 14,037 (32.2) | 3565 (32.7) | 6162 (31.7) |
| Missing | 1135 (1.5) | 738 (1.7) | 168 (1.5) | 229 (1.2) |
| Bystander AED use | ||||
| Yes | 3191 (4.3) | 1938 (4.4) | 465 (4.3) | 788 (4.1) |
| No | 70,160 (94.9) | 41,341 (94.9) | 10,347 (95.0) | 18,472 (95.0) |
| Missing | 554 (0.7) | 297 (0.7) | 82 (0.8) | 175 (0.9) |
| Initial rhythm | ||||
| Shockable | 12,524 (16.9) | 7512 (17.2) | 1838 (16.9) | 3174 (16.3) |
| Non-shockable | 61,123 (82.7) | 35,882 (82.3) | 9007 (82.7) | 16,234 (83.5) |
| Missing | 258 (0.3) | 182 (0.4) | 49 (0.4) | 27 (0.1) |
| EMS team level | ||||
| Advanced | 70,855 (95.9) | 41,405 (95.0) | 10,347 (95.0) | 19,103 (98.3) |
| Basic | 3050 (4.1) | 2171 (5.0) | 547 (5.0) | 332 (1.7) |
| Prehospital mechanical CPR | 10,330 (14.0) | 4589 (10.5) | 1188 (10.9) | 4553 (23.4) |
| RTI, min | 7 (5–9) | 7 (5–9) | 7 (5–9) | 7 (5–9) |
| On-scene resuscitation time, min | 13 (10–17) | 13 (9–17) | 13 (9–17) | 14 (10–17) |
| TTI, min | 6 (4–10) | 6 (4–10) | 6 (4–10) | 6 (4–10) |
| Prehospital airway | ||||
| Endotracheal intubation | 5989 (8.1) | 3742 (8.6) | 906 (8.3) | 1341 (6.9) |
| Supraglottic airway | 48,994 (66.3) | 27,585 (63.3) | 6836 (62.8) | 14,573 (75.0) |
| No | 18,922 (25.6) | 12,249 (28.1) | 3152 (28.9) | 3521 (18.1) |
| Prehospital epinephrine | 11,725 (15.9) | 6136 (14.1) | 1495 (13.7) | 4094 (21.1) |
| On-scene ROSC | 6962 (9.4) | 4022 (9.2) | 985 (9.0) | 1955 (10.1) |
| ED level | ||||
| Level 1–2 | 49,440 (66.9) | 28,879 (66.3) | 7130 (65.4) | 13,431 (69.1) |
| Level 3 | 24,465 (33.1) | 14,697 (33.7) | 3764 (34.6) | 6004 (30.9) |
| ECPR | 422 (0.6) | 238 (0.5) | 50 (0.5) | 134 (0.7) |
| Time from call to ECPR pump-on, min | 79 (64–97) | 78 (62–95) | 84 (58–109) | 83 (67–97) |
| Immediate PCI | 2042 (2.8) | 1155 (2.7) | 301 (2.8) | 586 (3.0) |
| Time from call to immediate PCI, min | 123 (98–162) | 120 (98–158) | 121 (97–163) | 125 (100–168) |
| Survived to hospital discharge | 7039 (9.5) | 4136 (9.5) | 1043 (9.6) | 1860 (9.6) |
| Good neurological recovery | 3709 (5.0) | 2125 (4.9) | 543 (5.0) | 1041 (5.4) |
Categorical variables are presented as numbers (percentages) and continuous variables are presented as medians (interquartile ranges). Immediate PCI is defined as PCI within 6 h from emergency call.
ECPR extracorporeal cardiopulmonary resuscitation, EMS emergency medical services, CPR cardiopulmonary resuscitation, AED automated external defibrillator, RTI response time interval, TTI transport time interval, ROSC return of spontaneous circulation, ED emergency department, PCI percutaneous coronary intervention.