Four RCTs (1,503 participants) were included. All trials scored 4 out of 5 for quality. All had appropriate methods of randomisation, were single blinded (not defined) and reported drop-outs. Tests showed no evidence of publication bias.
The average weighted proportion of people who survived to hospital discharge was 12% (95% CI 6.4% to 19.1%) in the chest compression-first group and 11.4% (95% CI 7.1% to 16.6%) in the defibrillation-first group. There was no statistically significant difference between compression first and defibrillation first for the outcomes of return of spontaneous circulation (I2=%), survival to hospital discharge (I2=34.4%), favourable neurological outcomes (I2=74.9%) and one-year survival (I2=0%).
Subgroup analyses investigated response times of five minutes or less and more than five minutes showed no statistically different outcomes. Meta-regression showed that a longer response time was associated with an increased benefit of chest compression before defibrillation.
Results for sensitivity analyses were similar to the main analyses.