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Table 2 Results of the summary effect estimates for the primary outcome

From: Intraosseous versus intravenous vascular access during cardiopulmonary resuscitation for out-of-hospital cardiac arrest: a systematic review and meta-analysis of observational studies

Analysis Outcome or moderator variables Number of included studies Odds ratio (95% confidence interval) I2, % p for mixed-effects meta-regression analysis
Main analysis Favorable neurological outcome at hospital discharge 6 [19, 20, 22,23,24,25] 0.60 (0.27–1.33) 95 NA
Subgroup analysis
 Study period Before 2010 1 [19] 0.22 (0.11–0.42) 0 0.19
After 2010 5 [20, 22,23,24,25] 0.73 (0.33–1.63) 94  
 Study region North America 4 [19, 20, 23, 25] 0.60 (0.20–1.79) 94 > 0.99
Europe 2 [22, 24] 0.57 (9.94E-06-32,578.24) 94  
 Selection of vascular access First attempted vascular access 3 [19, 20, 25] 0.49 (0.09–2.66) 94 0.56
Actual vascular access 3 [22,23,24] 0.73 (0.07–7.22) 95  
 EMS response time Longer than 10 mins 1 [22] 1.30 (0.97–1.73) 0 0.29
Shorter than 10 mins 5 [19, 20, 23,24,25] 0.51 (0.21–1.26) 94  
 Time to intervention Timing adjusted in analysis 4 [20, 22, 23, 25] 0.89 (0.48–1.66) 89 0.02
Timing not adjusted in analysis 2 [19, 24] 0.22 (0.17–0.30) 0  
 Type of effect estimates pooled in analysis Adjusted effect estimates 5 [19, 20, 22, 23, 25] 0.71 (0.30–1.65) 95 0.25
Unadjusted effect estimates 1 [24] 0.23 (0.11–0.50) 0  
Initial arrest rhythm Shockable rhythms 4 [19, 20, 23, 25] 0.64 (0.27–1.53) 90 NA