Impact of coma duration on functional outcomes at discharge and long-term survival after cardiac arrest.

Introduction: Awakening from coma is crucial for survivors of cardiac arrest, though coma duration is variable. We tested the association of coma duration with short-term functional recovery and long-term survival after cardiac arrest.

Methods: In this retrospective cohort study, we identified post-arrest patients who were comatose on presentation but awakened during hospitalization. We recorded demographics, arrest characteristics, days from arrest to awakening, and modified Rankin Scale (mRS) at hospital discharge. We compared discharge mRS between patients with short and long coma duration dichotomized at its median, 3, and 6 days. We compared long-term survival between patients with short and long coma duration who survived to hospital discharge. Finally, we used Cox regression to quantify the independent association of coma duration with survival after adjusting for patient and arrest characteristics.

Results: We included 979 subjects with median coma duration 2 [IQR 1-4] days. Shorter coma duration was associated with a higher proportion of patients with discharge mRS ≤ 3 (p < 0.001). We observed 742 subjects who survived to discharge for 3,136 person-years and found no difference in long-term survival between short and long coma durations (p = 0.86). Coma duration was not associated with hazard of death (HR 1.00, 95 %CI 0.97-1.03) after adjusting for age, location of arrest, Charlson Comorbidity Index, and discharge mRS.

Conclusions: Shorter coma duration was associated with better functional outcome at discharge, but not with long-term survival.