Delayed Neurologic Improvement and Long-Term Survival of Patients with Poor Neurologic Status after Out-of-hospital Cardiac Arrest: A Retrospective Cohort Study in Japan.

Aim: To assess survival duration and frequency of delayed neurologic improvement in patients with poor neurologic status at discharge from emer-gency hospitals after out-of-hospital cardiac arrest (OHCA). Methods: This retrospective cohort study included OHCA patients admitted to two tertiary emergency hospitals in Japan between January 2014 and December 2020. Pre-hospital, tertiary emergency hospital, and post-acute care hospital data, were retrospectively collected by reviewing medical records. Neurologic improvements were defined as an improvement of Cerebral Performance Category (CPC) scores from 3 or 4 at hospital dis -charge to 1 or 2. The primary outcome was neurologic improvement after discharge, while the secondary outcome was survival time after cardiac arrest. Results: Of all patients (n = 1,012) admitted to tertiary emergency hospitals after OHCA during the observation period, 239 with CPC 3 or 4 at discharge were included, and all were Japanese. Median age was 75 years, 64% were male, and 31% had initially shockable rhythms. Neurologic improvements were observed in nine patients (3.6%), higher in CPC 3 (31%) than CPC 4 (1.3%) patients, but not after 6 months from cardiac arrest. The median survival time after cardiac arrest was 386 days (95% confidence interval: 303-469). Conclusion: Survival probability in patients with CPC 3 or 4 was 50% at 1-year and 20% at 3-year. Neurologic improvements were observed in 3.6% patients, higher in CPC 3 than in CPC 4 patients. During the first 6 months after OHCA, the neurologic status may improve in patients with CPC 3 or 4.