Table 1. Patient, Cardiac Arrest Event, Layperson and EMS Interventions, and EMS Agency Characteristics, Stratified by Quartiles of Survival at EMS Agency.
| Characteristic | No. (%) | ||||
|---|---|---|---|---|---|
| Total | EMS Agencies With Survival Rates in Lowest Quartilea | EMS Agencies With Survival Rates in Second-Lowest Quartilea | EMS Agencies With Survival Rates in Second-Highest Quartilea | EMS Agencies With Survival Rates in Highest Quartilea | |
| Patients | 43 656 | 12 272 (28.1) | 17 842 (40.9) | 6701 (15.3) | 6841 (15.7) |
| EMS agencies | 112 (100) | 28 (25.0) | 28 (25.0) | 28 (25.0) | 28 (25.0) |
| Patient demographics | |||||
| Age, median (IQR), y | 66.0 (54.0-79.0) | 67.0 (55.0-79.0) | 67.0 (55.0-80.0) | 67.0 (54.0-79.0) | 65.0 (53.0-77.0) |
| Sex | |||||
| Male | 27 524 (63.0) | 7379 (60.1) | 11 339 (63.6) | 4362 (65.1) | 4444 (65.0) |
| Unknown | 18 (0.0) | 1 (0.0) | 8 (0.0) | 5 (0.1) | 4 (0.1) |
| Cardiac arrest event characteristics | |||||
| Year of arrest | |||||
| 2011 | 4508 (10.3) | 1192 (9.7) | 1927 (10.8) | 682 (10.2) | 707 (10.3) |
| 2012 | 10 118 (23.2) | 2562 (20.9) | 4222 (23.7) | 1672 (25.0) | 1662 (24.3) |
| 2013 | 11 242 (25.8) | 3156 (25.7) | 4617 (25.9) | 1744 (26.0) | 1725 (25.2) |
| 2014 | 11 903 (27.3) | 3630 (29.6) | 4693 (26.3) | 1706 (25.5) | 1874 (27.4) |
| 2015 | 5885 (13.5) | 1732 (14.1) | 2383 (13.4) | 897 (13.4) | 873 (12.8) |
| Initial rhythm | |||||
| Shockable | 9717 (22.3) | 2317 (18.9) | 3942 (22.1) | 1637 (24.4) | 1821 (26.6) |
| Nonshockable | 33 084 (75.8) | 9730 (79.3) | 13 581 (76.1) | 4908 (73.2) | 4865 (71.1) |
| Unknown | 855 (1.9) | 225 (1.8) | 319 (1.8) | 156 (2.3) | 155 (2.2) |
| Location | |||||
| Public | 6235 (14.3) | 1502 (12.2) | 2588 (14.5) | 982 (14.7) | 1163 (17.0) |
| Home | 31 846 (72.9) | 8641 (70.4) | 13 438 (75.3) | 4987 (74.4) | 4780 (69.9) |
| Other | 5475 (12.5) | 2096 (17.1) | 1760 (9.9) | 724 (10.8) | 895 (13.1) |
| Unknown | 100 (0.2) | 33 (0.3) | 56 (0.3) | 8 (0.1) | 3 (0.0) |
| Witnessed collapse | |||||
| Bystander | 15 949 (36.5) | 4217 (34.4) | 6477 (36.3) | 2644 (39.5) | 2611 (38.2) |
| EMS | 5398 (12.4) | 1514 (12.3) | 2228 (12.5) | 798 (11.9) | 858 (12.5) |
| None | 21 270 (48.7) | 6212 (50.6) | 8617 (48.3) | 3140 (46.9) | 3301 (48.3) |
| Unknown | 1039 (2.4) | 329 (2.7) | 520 (2.9) | 119 (1.8) | 71 (1.0) |
| Layperson interventions | |||||
| None | 24 042 (55.1) | 7318 (59.6) | 10 160 (56.9) | 3573 (53.3) | 2991 (43.7) |
| Layperson CPR only | 16 831 (38.6) | 4187 (34.1) | 6685 (37.5) | 2659 (39.7) | 3300 (48.2) |
| Layperson CPR and public access AED use | 1931 (4.4) | 529 (4.3) | 652 (3.7) | 334 (5.0) | 416 (6.1) |
| Unknown | 852 (2.0) | 238 (1.9) | 345 (1.9) | 135 (2.0) | 134 (2.0) |
| EMS interventions | |||||
| No. of treating EMS personnel within 15 min after 911 call | |||||
| Mean (SD) | 5.6 (2.1) | 5.3 (1.8) | 5.5 (2.0) | 5.4 (2.1) | 7.0 (2.3) |
| ≤6 | 31 068 (71.2) | 10 266 (83.7) | 13 342 (74.8) | 4733 (70.6) | 2727 (39.9) |
| >6 | 12 511 (28.7) | 1947 (15.9) | 4482 (25.1) | 1968 (29.4) | 4114 (60.1) |
| Unknown | 77 (0.2) | 59 (0.5) | 18 (0.1) | 0 (0.0) | 0 (0.0) |
| EMS response time (time interval from first telephone call to first EMS arrival) | |||||
| Median (IQR), min | 5.4 (4.2-6.9) | 5.1 (4.0-6.6) | 5.5 (4.2-7.0) | 5.9 (4.7-7.4) | 5.1 (4.0-6.4) |
| Unknown | 521 (1.2) | 279 (2.3) | 187 (1.0) | 45 (0.7) | 10 (0.1) |
| Time interval from first telephone call to defibrillation | |||||
| Median (IQR), min | 12.2 (9.1-20.1) | 13.0 (9.4-22.1) | 12.2 (9.2-19.6) | 12.3 (9.5-19.9) | 11.0 (8.4-19.0) |
| Unknown | 29 466 (67.5) | 8914 (72.6) | 11 915 (66.8) | 4413 (65.9) | 4224 (61.7) |
| Epinephrine administration | |||||
| Yes | 36 907 (84.5) | 10 580 (86.2) | 15 330 (85.9) | 5512 (82.3) | 5485 (80.2) |
| No | 6715 (15.4) | 1679 (13.7) | 2497 (14.0) | 1183 (17.7) | 1356 (19.8) |
| Unknown | 34 (0.1) | 13 (0.1) | 15 (0.1) | 6 (0.1) | 0 (0.0) |
| Attempted advanced airway | |||||
| Yes | 34 392 (78.8) | 9576 (78.0) | 13 614 (76.3) | 5230 (78.0) | 5972 (87.3) |
| No | 9222 (21.1) | 2679 (21.8) | 4211 (23.6) | 1463 (21.8) | 869 (12.7) |
| Unknown | 42 (0.1) | 17 (0.1) | 17 (0.1) | 8 (0.1) | 0 (0.0) |
| Chest compression fraction | |||||
| Median (IQR) | 0.85 (0.77-0.91) | 0.83 (0.74-0.90) | 0.85 (0.76-0.91) | 0.85 (0.77-0.91) | 0.89 (0.81-0.95) |
| Unknown | 8212 (18.8) | 2626 (21.4) | 2986 (16.7) | 1478 (22.1) | 1122 (16.4) |
| Chest compression rate | |||||
| Median (IQR), per minute | 108.5 (102.1-116.4) |
107.9 (101.5-117.3) |
108.0 (102.0-115.5) |
108.9 (102.5-117.1) |
110.1 (104.0-116.7) |
| Unknown | 8387 (19.2) | 2424 (19.8) | 3013 (16.9) | 1449 (21.6) | 1501 (21.9) |
| EMS agency characteristics | |||||
| Crew composition of primary EMS agency | |||||
| BLS | 9848 (22.6) | 2912 (23.7) | 2049 (11.5) | 3211 (47.9) | 1676 (24.5) |
| ALS | 949 (2.2) | 96 (0.8) | 0 (0.0) | 406 (6.1) | 447 (6.5) |
| BLS/ALS | 32 859 (75.3) | 9264 (75.5) | 15 793 (88.5) | 3084 (46.0) | 4718 (69.0) |
| Proportion of patients who received resuscitation attempt among EMS-assessed OHCA in each EMS agency, mean (SD), % | 54.0 (15.5) | 57.8 (18.0) | 50.2 (11.6) | 58.9 (16.9) | 52.5 (15.7) |
| ALS-BLS tiered response system | 25 642 (58.7) | 4466 (36.4) | 11 561 (64.8) | 4421 (66.0) | 5194 (75.9) |
| Area of EMS agency coverage | |||||
| Rural | 1835 (4.2) | 803 (6.5) | 94 (0.5) | 535 (8.0) | 403 (5.9) |
| Suburban | 8329 (19.1) | 288 (2.3) | 3005 (16.8) | 2781 (41.5) | 2255 (33.0) |
| Urban | 33 492 (76.7) | 11 181 (91.1) | 14 743 (82.6) | 3385 (50.5) | 4183 (61.1) |
Abbreviations: AED, automated external defibrillator; ALS, advanced life support; BLS, basic life support; CPR, cardiopulmonary resuscitation; EMS, emergency medical services; IQR, interquartile range.
a
Quartiles for survival rates were 0% to 8.46% (lowest); 8.47% to 12.54% (second lowest), 12.55% to 15.84% (second highest), and 15.85% to 28.95% (highest).