Table 1 Baseline characteristics of the multiply imputed dataset before and after propensity score matching
Unmatched cohort | Matched cohort | |||||
|---|---|---|---|---|---|---|
Variables | Open-chest CPR | Closed-chest CPR | SMD | Open-chest CPR | Closed-chest CPR | SMD |
Number of subjects | 2192 | 4318 | 1804 | 1825 | ||
Age (years) | 52 (34–68) | 56 (36–73) | 0.12 | 52 (34–68) | 53 (34–71) | 0.05 |
Sex, male, n (%) | 1533 (69.9) | 2865 (66.4) | 0.08 | 1250 (69.3) | 1248 (69.2) | 0.00 |
Year of Injury, n (%) | ||||||
2004 | 65 (3.0) | 170 (3.9) | 0.05 | 63 (3.5) | 63 (3.5) | 0.00 |
2005 | 58 (2.6) | 181 (4.2) | 0.08 | 56 (3.1) | 57 (3.1) | 0.00 |
2006 | 77 (3.5) | 168 (3.9) | 0.02 | 75 (4.2) | 56 (3.1) | 0.06 |
2007 | 106 (4.8) | 323 (7.5) | 0.11 | 100 (5.5) | 94 (5.2) | 0.01 |
2008 | 155 (7.1) | 319 (7.4) | 0.01 | 144 (8.0) | 126 (7.0) | 0.04 |
2009 | 155 (7.1) | 313 (7.2) | 0.01 | 144 (8.0) | 135 (7.5) | 0.02 |
2010 | 273 (12.5) | 468 (10.8) | 0.05 | 249 (13.8) | 232 (12.9) | 0.03 |
2011 | 240 (10.9) | 541 (12.5) | 0.05 | 216 (13.0) | 203 (11.3) | 0.02 |
2012 | 300 (13.7) | 544 (12.6) | 0.03 | 251 (13.9) | 251 (13.9) | 0.00 |
2013 | 283 (12.9) | 542 (12.6) | 0.01 | 223 (12.4) | 226 (12.5) | 0.01 |
2014 | 267 (12.2) | 423 (9.8) | 0.08 | 161 (8.9) | 201 (11.1) | 0.07 |
2015 | 213 (9.7) | 326 (7.5) | 0.08 | 122 (6.8) | 160 (8.9) | 0.08 |
Vital signs at the scene of injury | ||||||
Systolic blood pressure, mmHg | 76 (0–109) | 67 (0–107) | 0.11 | 71 (0–107) | 68 (0–104) | 0.06 |
Heart rate, beats/min | 60 (0–108) | 0 (0–90) | 0.28 | 53 (0–100) | 30 (0–100) | 0.06 |
Respiratory rate, breaths/min | 10 (0–24) | 0 (0–20) | 0.26 | 6 (0–24) | 0 (0–24) | 0.05 |
Cardiac arrest at the scene of injury, n (%) | 798 (36.4) | 1881 (43.6) | 0.15 | 714 (39.6) | 771 (42.7) | 0.06 |
Pre-hospital treatment, n (%) | ||||||
Chest compression | 1045 (47.7) | 2518 (58.3) | 0.21 | 935 (51.8) | 943 (52.3) | 0.01 |
Defibrillation | 34 (1.6) | 106 (2.5) | 0.06 | 31 (1.7) | 36 (2.0) | 0.02 |
Time from EMS dispatch to ED arrival, mins | 33 (25–45) | 32 (25–42) | 0.00 | 32 (25–44) | 32 (25–44) | 0.01 |
Vital signs on ED arrival | ||||||
Systolic blood pressure, mmHg | 0 (0–40) | 0 (0–40) | 0.00 | 0 (0–40) | 0 (0–40) | 0.01 |
Heart rate, beats/min | 0 (0–84) | 0 (0–60) | 0.16 | 0 (0–75) | 0 (0–72) | 0.01 |
Respiratory rate, breaths/min | 0 (0–15) | 0 (0–0) | 0.14 | 0 (0–8) | 0 (0–10) | 0.05 |
Body temperature, °C | 35.2 (34.2–36.0) | 35.2 (34.2–36.1) | 0.00 | 35.2 (34.2–36.0) | 35.2 (34.2–36.0) | 0.02 |
Glasgow coma scale on ED arrival | 3 (3–3) | 3 (3–3) | 0.07 | 3 (3–3) | 3 (3–3) | 0.02 |
Revised trauma score on ED arrival | 0.00 (0.00–2.34) | 0.00 (0.00–1.47) | 0.06 | 0.00 (0.00–1.90) | 0.00 (0.00–1.90) | 0.00 |
Cardiac arrest on ED arrival, n (%) | 1480 (67.5) | 3110 (72.0) | 0.10 | 1266 (70.2) | 1272 (70.5) | 0.01 |
Abbreviated injury scale | ||||||
Head | 0 (0–3) | 3 (0–4) | 0.47 | 0 (0–3) | 0 (0–3) | 0.04 |
Face | 0 (0–0) | 0 (0–0) | 0.12 | 0 (0–0) | 0 (0–0) | 0.01 |
Neck | 0 (0–0) | 0 (0–0) | 0.02 | 0 (0–0) | 0 (0–0) | 0.01 |
Chest | 4 (3–5) | 4 (0–5) | 0.37 | 4 (3–5) | 4 (3–5) | 0.01 |
Abdomen | 0 (0–2) | 0 (0–0) | 0.37 | 0 (0–0) | 0 (0–0) | 0.02 |
Spine | 0 (0–0) | 0 (0–0) | 0.07 | 0 (0–0) | 0 (0–0) | 0.00 |
Upper extremities | 0 (0–0) | 0 (0–1) | 0.03 | 0 (0–1) | 0 (0–1) | 0.01 |
Pelvis and lower extremities | 2 (0–3) | 2 (0–3) | 0.14 | 2 (0–3) | 2 (0–3) | 0.02 |
Surface | 0 (0–0) | 0 (0–0) | 0.09 | 0 (0–0) | 0 (0–0) | 0.00 |
Injury severity score | 34 (25–43) | 29 (22–41) | 0.22 | 34 (25–43) | 34 (25–43) | 0.02 |
Probability of survival, % | 3.6 (1.1–14.4) | 3.6 (1.2–13.4) | 0.01 | 3.6 (1.2–13.4) | 3.6 (1.0–13.4) | 0.00 |