Table 1. Comparison of Hypothermia-treated and Non-Hypothermia-treated Patients Before and After Propensity Score Matching.
Patient and cardiac arrest factors were well-balanced (i.e., standardized differences <10%) after propensity score matching
| BEFORE PROPENSITY SCORE MATCHING
|
AFTER PROPENSITY SCORE MATCHING
|
|||||
|---|---|---|---|---|---|---|
| Hypothermia (n = 1568) |
Non-Hypothermia (n = 24,615) |
P value | Hypothermia (n = 1524) |
Non-Hypothermia (n =3714) |
Standardized Differences, % |
|
| DEMOGRAPHICS | ||||||
| Age, mean ± SD | 61.5 ± 16.2 | 63.9 ± 16.9 | <0.001 | 61.6 ± 16.2 | 62.2 ± 17.5 | 3.2 |
| Male sex | 908 (57.9%) | 13,750 (55.9%) | 0.11 | 892 (58.5%) | 2120 (57.1%) | 1.7 |
| Race | 0.07 | 5.0 | ||||
| White | 1044 (66.6%) | 17,184 (69.8%) | 1015 (66.6%) | 2548 (68.6%) | ||
| Black | 377 (24.0%) | 5315 (21.6%) | 366 (24.0%) | 870 (23.4%) | ||
| Other | 147 (9.4%) | 2116 (8.6%) | 143 (9.4%) | 296 (8.0%) | ||
| CARDIAC ARREST FACTORS | ||||||
| CPR duration (minutes), mean ± SD | 16.5 ± 18.7 | 16.3 ± 19.0 | 0.78 | 16.5 ± 18.7 | 16.3 ± 18.8 | 2.7 |
| CPR duration (minutes), median (IQR) | 11.0 (8.0, 22.0) | 10.0 (8.0, 21.0) | 0.09 | 11.0 (8.0, 22.0) | 11.0 (8.0, 21.0) | NA¶ |
| Location of arrest | <0.001 | 8.3 | ||||
| Intensive care unit | 852 (54.3%) | 15,908 (64.6%) | 830 (54.5%) | 2208 (59.5%) | ||
| Telemetry unit | 126 (8.0%) | 2495 (10.1%) | 126 (8.3%) | 330 (8.9%) | ||
| Non-monitored hospital unit | 152 (9.7%) | 2248 (9.1%) | 149 (9.8%) | 347 (9.3%) | ||
| Emergency room | 254 (16.2%) | 2046 (8.3%) | 248 (16.3%) | 475 (12,8%) | ||
| Procedural area | 165 (10.5%) | 1737 (7.1%) | 154 (10.1%) | 319 (8.6%) | ||
| Other | 19 (1.2%) | 181 (0.7%) | 17 (1.1%) | 35 (0.9%) | ||
| Time of Arrest | ||||||
| Night (11 PM to 6:59 AM) | 451 (28.8%) | 7693 (31.3%) | 0.04 | 436 (28.6%) | 1101 (29.6%) | 1.3 |
| Weekend | 492 (31.4%) | 7846 (31.9%) | 0.68 | 481 (31.6%) | 1171 (31.5%) | 0.1 |
| Initial Cardiac Arrest Rhythm | <0.001 | 2.7 | ||||
| Asystole | 407 (26.0%) | 7016 (28.5%) | 397 (26.0%) | 1000 (26.9%) | ||
| Pulseless Electrical Activity | 735 (46.9%) | 12,785 (51.9%) | 715 (46.9%) | 1832 (49.3%) | ||
| Ventricular Fibrillation | 263 (16.8%) | 2548 (10.4%) | 254 (16.7%) | 500 (13.5%) | ||
| Pulseless Ventricular Tachycardia | 163 (10.4%) | 2266 (9.2%) | 158 (10.4%) | 382 (10.3%) | ||
| PRE-EXISTING CONDITIONS | ||||||
| Heart failure this admission | 250 (15.9%) | 4423 (18.0%) | 0.04 | 244 (16.0%) | 581 (15.6%) | 0.3 |
| Heart failure prior to admission | 310 (19.8%) | 5030 (20.4%) | 0.53 | 304 (19.9%) | 717 (19.3%) | 1.5 |
| MI this admission | 346 (22.1%) | 3804 (15.5%) | <0.001 | 338 (22.2%) | 728 (19.6%) | 5.2 |
| MI prior to admission | 252 (16.1%) | 3600 (14.6%) | 0.12 | 248 (16.3%) | 570 (15.3%) | 2.0 |
| Hypotension* | 494 (31.5%) | 8817 (35.8%) | <0.001 | 473 (31.0%) | 1239 (33.4%) | 3.9 |
| Respiratory insufficiency* | 818 (52.2%) | 13,828 (56.2%) | 0.001 | 797 (52.3%) | 2015 (54.3%) | 2.3 |
| Renal insufficiency* | 514 (32.8%) | 9289 (37.7%) | <0.001 | 502 (32.9%) | 1248 (33.6%) | 0.7 |
| Hepatic insufficiency* | 106 (6.8%) | 2300 (9.3%) | <0.001 | 103 (6.8%) | 307 (8.3%) | 4.5 |
| Metabolic or electrolyte abnormality* | 310 (19.2%) | 5197 (21.1%) | 0.07 | 291 (19.1%) | 740 (19.9%) | 1.3 |
| Diabetes mellitus | 475 (30.3%) | 7545 (30.7%) | 0.77 | 462 (30.3%) | 1062 (28.6%) | 2.4 |
| Baseline depression in CNS function | 216 (13.8%) | 3341 (13.6%) | 0.82 | 211 (13.8%) | 495 (13.3%) | 0.1 |
| Major trauma | 71 (4.5%) | 1702 (6.9%) | <0.001 | 68 (4.5%) | 215 (5.8%) | 5.4 |
| Acute stroke | 50 (3.2%) | 1125 (4.6%) | 0.01 | 49 (3.2%) | 133 (3.6%) | 2.1 |
| Pneumonia | 227 (14.5%) | 4304 (17.5%) | 0.002 | 225 (14.8%) | 607 (16.3%) | 5.0 |
| Septicemia* | 263 (16.8%) | 5404 (22.0%) | <0.001 | 258 (16.9%) | 716 (19.3%) | 4.6 |
| Metastatic or hematologic malignancy | 122 (7.8%) | 2784 (11.3%) | <0.001 | 119 (7.8%) | 355 (9.6%) | 5.5 |
| INTERVENTIONS IN PLACE AT TIME OF ARREST | ||||||
| Continuous intravenous vasopressor | 572 (36.5%) | 9157 (37.2%) | 0.57 | 554 (36.4%) | 1371 (36.9%) | 1.1 |
| Dialysis/extracorporeal filtration | 53 (3.4%) | 1144 (4.6%) | 0.02 | 52 (3.4%) | 126 (3.4%) | 0.1 |
| Pre-existing ICD | 31 (2.0%) | 444 (1.8%) | 0.62 | 30 (2.0%) | 75 (2.0%) | 0.0 |
Abbreviations: CNS, central nervous system; CPR, cardiopulmonary resuscitation; ICD, implantable cardioverter-defibrillator; IQR, interquartile range; MI, myocardial infarction; NA, not applicable; SD, standard deviation
*
Denotes conditions which were present within 24 hours of cardiac arrest
¶
Standardized difference cannot be calculated for a comparison of medians