Table 2. Variation in Survival and Functional Outcomes After EMS-Treated Out-of-Hospital Cardiac Arrest Between EMS Agencies.
| Adjustment | Median Odds Ratios for EMS Agency Effect (95% CI) | ||
|---|---|---|---|
| Survival to Hospital Discharge | Favorable Functional Outcome at Discharge | Return of Spontaneous Circulation at Emergency Department Arrival | |
| EMS-Treated Out-of-Hospital Cardiac Arrest | |||
| Patients, No. | 32 533 | 18 442 | 32 528 |
| Adjustments | |||
| Unadjusted | 1.43 (1.34-1.54) | 1.54 (1.40-1.73) | 1.53 (1.43-1.65) |
| 1a | 1.42 (1.33-1.53) | 1.56 (1.42-1.76) | 1.53 (1.43-1.65) |
| 2b | 1.45 (1.35-1.58) | 1.60 (1.44-1.83) | 1.57 (1.47-1.70) |
| 3c | 1.43 (1.34-1.56) | 1.58 (1.42-1.81) | 1.56 (1.46-1.69) |
| 4d | 1.57 (1.45-1.74) | 1.59 (1.41-1.85) | 1.54 (1.44-1.67) |
| 5e | 1.56 (1.44-1.73) | 1.53 (1.37-1.78) | 1.50 (1.41-1.62) |
| EMS-Treated Shockable Out-of-Hospital Cardiac Arrest | |||
| Patients, No. | 7602 | 4421 | 7600 |
| Adjustments | |||
| Unadjusted | 1.39 (1.30-1.52) | 1.51 (1.36-1.72) | 1.55 (1.43-1.70) |
| 1a | 1.41 (1.31-1.55) | 1.56 (1.40-1.79) | 1.56 (1.44-1.73) |
| 2b | 1.43 (1.33-1.58) | 1.54 (1.39-1.77) | 1.59 (1.46-1.76) |
| 3c | 1.39 (1.29-1.54) | 1.50 (1.35-1.72) | 1.57 (1.44-1.73) |
| 4d | 1.53 (1.39-1.73) | 1.57 (1.39-1.85) | 1.63 (1.49-1.83) |
| 5e | 1.53 (1.39-1.73) | 1.48 (1.32-1.75) | 1.58 (1.44-1.76) |
| EMS-Treated Nonshockable Out-of-Hospital Cardiac Arrest | |||
| Patients, No. | 24 931 | 14 021 | 24 928 |
| Adjustments | |||
| Unadjusted | 1.61 (1.45-1.82) | 1.66 (1.42-2.08) | 1.59 (1.48-1.74) |
| 1a | 1.57 (1.42-1.78) | 1.66 (1.42-2.08) | 1.59 (1.48-1.74) |
| 2b | 1.57 (1.42-1.79) | 1.69 (1.44-2.15) | 1.62 (1.50-1.78) |
| 3c | 1.58 (1.43-1.80) | 1.71 (1.45-2.17) | 1.62 (1.50-1.78) |
| 4d | 1.69 (1.51-1.94) | 1.56 (1.31-2.06) | 1.56 (1.45-1.71) |
| 5e | 1.64 (1.47-1.89) | 1.43 (1.21-1.98) | 1.52 (1.41-1.65) |
Abbreviation: EMS, emergency medical services.
Adjustment 1 was for patient demographics: patient age and sex.
Adjustment 2 was for patient demographics, as above, and cardiac arrest event characteristics: year of arrest, initial rhythm, location of arrest, and witnessed collapse.
Adjustment 3 was for patient demographics and cardiac arrest event characteristics, as above, and layperson interventions: layperson cardiopulmonary resuscitation and public access automated external defibrillator use.
Adjustment 4 was for patient demographics, cardiac arrest event characteristics, and layperson interventions, as above, and EMS interventions: number of treating EMS personnel within 15 minutes after emergency telephone call, EMS response time, epinephrine administration, attempted advanced airway, chest compression fraction, and chest compression rate.
Adjustment 5 was for patient demographics, cardiac arrest event characteristics, layperson interventions, and EMS interventions, as above, and EMS agency-level variables: EMS crew composition characteristics, proportion of patients who received any resuscitation attempt among EMS-assessed out-of-hospital cardiac arrest, advanced life support–basic life support tiered system, and area of EMS coverage.