Table 1.
Characteristics of matched subjects transported by HEMS or GEMS
| HEMS n = 155,691 |
GEMS n = 155,691 |
Standardized difference* | |
|---|---|---|---|
| Age [years, med (IQR)] | 39 (25, 54) | 39 (24, 57) | −0.083 |
| Sex [n (%) male] | 110,565 (71) | 106,941 (69) | 0.045 |
| Race [n (%)] | −0.219 | ||
| Caucasian | 128,029 (82) | 114,262 (73) | |
| Non-Caucasian | 27,662 (18) | 41,429 (27) | |
| Insurance Status [n (%)] | 0.131 | ||
| Commercial | 80,959 (52) | 70,527 (45) | |
| Subsidized/None | 74,732 (48) | 85,164 (52) | |
| Mechanism [penetrating, n (%)] | 13,115 (8) | 17,958 (12) | −0.107 |
| Prehospital response time [mins, med (IQR)] | 19 (13, 25) | 20 (13, 27) | −0.057 |
| Prehospital scene time [mins, med (IQR)] | 14 (10, 21) | 15 (10, 21) | 0.001 |
| Prehospital transport time [mins, med (IQR)] | 21 (16, 30) | 24 (15, 36) | −0.203 |
| Prehospital SBP [mmHg, med (IQR)] | 131 (115, 147) | 132 (118, 148) | −0.018 |
| Prehospital HR [beats/min, med (IQR)] | 93 (80, 108) | 91 (80, 106) | 0.056 |
| Prehospital RR [breaths/min, med (IQR)] | 18 (16, 20) | 18 (16, 20) | −0.049 |
| Prehospital GCS [med (IQR)] | 15 (13, 15) | 15 (14, 15) | −0.123 |
| Anatomic triage criteria [n (%)] | 41,081 (26) | 36,750 (24) | 0.064 |
| ISS [med (IQR)] | 13 (6, 22) | 9 (4, 14) | 0.404 |
| TMPM predicted mortality [%, med(IQR)] | 2.7 (1.1, 10.7) | 1.7 (0.8, 4.7) | 0.214 |
| ICU admission [n (%)] | 75,499 (49) | 43,717 (28) | 0.423 |
| Urgent operation [n (%)] | 29,775 (19) | 20,353 (13) | 0.161 |
| Mechanical ventilation [n (%)] | 43,955 (28) | 23,535 (15) | 0.317 |
| Trauma center level | 0.455 | ||
| Level I/II | 150,159 (96) | 128,783 (83) | |
| Non-Level I/II | 5,532 (4) | 26,908 (17) | |
| In-hospital Survival [n (%)] | 142,968 (92) | 144,559 (93) | −0.039 |
*
Represents the standardized difference between groups after matching for variables used in propensity score estimation. Absolute values for the standardized difference >0.2 are considered to indicate imbalance between groups after matching.
HEMS, helicopter emergency medical services; GEMS, ground emergency medical services; med, median; IQR, interquartile range; SBP, systolic blood pressure; HR, heart rate; RR, respiratory rate; GCS, Glasgow Coma Scale; ISS, injury severity score; TMPM, trauma mortality prediction model; ICU, intensive care unit