Blood samples are collected at six months follow-up from adult survivors after out-of-hospital cardiac arrest. Patients will be informed about the study and if they consent to participation, venous blood will be drawn by authorised medical personnel. Plasma, serum and PAX-RNA will be collected (ca 15 ml in total), processed and frozen for analysis after trial completion.

Blood samples are collected at six months follow-up from adult survivors after out-of-hospital cardiac arrest. Patients will be informed about the study and if they consent to participation, venous blood will be drawn by authorised medical personnel. Plasma, serum and PAX-RNA will be collected (ca 15 ml in total), processed and frozen for analysis after trial completion.

Samples will be analysed in batch for biomarkers of brain injury, inflammation etc.

Primary outcome is functional outcome (modified Rankin Scale 4-6) at six months after cardiac arrest.

Secondary outcomes are neurocognitive function according to the Montreal Cognitive Assessment (MoCA), Symbol Digits Modalities Test (SDMT).

Inclusion Criteria:

• Survivors of out-of-cardiac arrest who participate in the extended follow-up study of the STEPCARE trial at selected sites only

Exclusion Criteria:

• Patients not participating in the extended follow-up at participating sites

Adult patients with an out-of-hospital cardiac arrest who survived to six months follow-up

Upon reasonable request after publication of results.