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Table 1 Baseline characteristics of the multiply imputed dataset before and after propensity score matching

From: Open-chest versus closed-chest cardiopulmonary resuscitation in blunt trauma: analysis of a nationwide trauma registry

  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
  1. Numeric variables are expressed as median (25th–75th percentiles). Abbreviations: CPR cardiopulmonary resuscitation, SMD standardized mean difference, EMS emergency medical services, ED emergency department