Table 3. Primary and Secondary Outcomes.
| OUTCOME | Intraosseous (IO) route | Intravenous (IV) route | Risk/mean difference (95% CI) † | Odds/hazard/incidence rate Ratio (95% CI) † | ||
|---|---|---|---|---|---|---|
| Unadjusted | Adjusted‡ | Unadjusted | Adjusted | |||
| Primary outcome | ||||||
| Survival at 30 days – no./total no. (%) |
137/3030 (4.5%) | 155/3034 (5.1%) | -0.6% (-1.7%, 0.5%) | -0.2% (-1.1%, 0.8%) | 0.880 (0.695, 1.113) |
0.945 (0.676, 1.322), p=0.741 |
| Secondary outcomes | ||||||
| Return to spontaneous circulation (ROSC) anytime – no./total no. (%) | 1092/3031 (36.0%) |
1186/3035 (39.1%) |
-3.0% (-5.5%, -0.6%) | -3.2% (-5.9%, - 0.6%) | 0.878 (0.791, 0.974) | 0.863 (0.765, 0.974) |
| Time to return of spontaneous circulation (ROSC)– mins- median (IQR) | 33 (24.0, 43.0) | 32 (24.0, 43.0) | 0.757 (-1.062, 2.576) | 0.451 (-0.818, 1.719) |
0.896 (0.823, 0.975)Δ | 0.889 (0.808, 0.979)Δ |
| Sustained return to spontaneous circulation (ROSC) at hospital handover – no./total no. (%) |
654/3016 (21.7%) | 744/3023 (24.6%) |
-2.9% (-5.1%, -0.8%) | -2.6% (-4.8%, - 0.3%) | 0.848 (0.752, 0.956) | 0.853 (0.741, 0.983) |
| Survival to hospital discharge - no./total no. (%) | 112/3012 (3.7%) | 120/3012 (4.0%) |
-0.3% (-1.2%, 0.7%) | 0.0% (-0.9%, 0.8%) | 0.931 (0.716, 1.210) |
0.996 (0.679, 1.461) |
| Length of hospital stay– days- median (IQR) | ||||||
| Patients who survived |
18.0 (11, 32) | 16.5 (7, 31) | 3.122 (-4.698, 10.942) | 7.681 (-4.392, 19.754) |
- | - |
| Patients who died | 0.0 (0, 0) | 0.0 (0, 0) | -0.229 (-0.483, 0.024) | -0.178 (-0.454, 0.098) | - | - |
| Favourable Neurological |
||||||
| Outcome at Hospital Discharge: Modified Rankin Scale at Discharge – no./total no. (%) |
||||||
| (0-3) favourable outcome |
80 (2.7%) | 85 (2.8%) | ||||
| (4-6) unfavourable outcome |
2914 (97.3%) | 2901 (97.2%) | -0.2% (-1.0%, 0.7%) | -0.1% (-0.8%, 0.6%) | 0.937 (0.687, 1.277) |
0.914 (0.567, 1.474) |
| Adverse event (per 1000 patients) |
1/3040 (0.33) | 0/3042 (0) | - | 1.003 (0.856, 1.176), p=0.968 | - | |
| Serious adverse event (per 1000 patients) | 0/3040 (0) | 0/3042 (0) | - | - | - | - |
IQR-Interquartile range
the risk difference (post-hoc test), hazard ratio (HR), incidence rate ratio (IRR) or mean difference are for IO versus IV. Risk difference are reported since odds ratios may over-estimate the magnitude of treatment effect. Treatment differences are adjusted for: age, sex, witness status (EMS versus bystander), bystander CPR (yes/no), initial rhythm (shockable versus non-shockable), time from emergency call to drug administration, etiology of cardiac arrest (medical versus non-medical). Risk of adverse event is assessed using Poisson regression and IRR is reported. No comparison is conducted for serious adverse event. Confidence interval widths have not been adjusted for multiplicity and may not be used in place of hypothesis testing.
Adjusted risk difference was estimated using SAS macro Margins (https://support.sas.com/kb/63/038.html).
Cause-specific hazard function was used to estimate the hazards of ROSC. Death before any ROSC is considered as a competing risk. Proportional hazard assumption was not violated for both unadjusted and adjusted analyses.
Modified Rankin Score is assessed on a 7-point scale from 0 to 6, namely: 0- No symptoms, 1- No significant disability, 2- Slight disability, 3- Moderate disability, 4- Moderate severe disability, 5- Severe disability, 6- Dead. A score of 0-3 is categorized as a favorable neurological outcome.19