2. Professional provided CPR.

Outcome	Continuous chest compression with asynchronous rescue breathing (raw data as provided in trial report)	Interrupted chest compression plus ventilation (raw data as provided in trial report)
Survival to hospital discharge (n/total n (%))	1129/12,613 (9.0)	1072/11,035 (9.7)
Survival to hospital admission (n/total n (%))	3108/12,653 (24.6)	2860/11,058 (25.9)
Neurological outcomes at hospital discharge (measured with modified Rankin scale ≤3) — (n/total n (%))	883/12,560 (7.0)	844/10,995 (7.7)
Return of spontaneous circulation at ED arrival (n/total n (%))	3058/12,646 (24.2)	2799/11,051 (25.3)
Adverse events (n/total n(%))	6889/12653 (54.4)	6127/11058 (55.4)

Data taken from Table 3 and from supplementary material provided in Nichol 2015.

Abbreviations and acronyms

ED: emergency department

n: number

Scores on the modified Rankin scale 3 or less indicates a favourable neurological function (0 indicates no symptoms and 6 indicates death).