Coma Duration Linked to Recovery at Discharge but Not Long-Term Survival After Cardiac Arrest: Study

"Shorter coma duration following cardiac arrest was linked to improved functional recovery at discharge, with a greater proportion of patients attaining a modified Rankin Scale (mRS) score of ≤3. However, coma duration did not affect long-term survival. Even after adjusting for variables such as age, arrest location, and comorbidities, no association was found between coma duration and long-term mortality (HR 1.00), suggesting it does not confer a survival advantage," the researchers reported.

Regaining consciousness is a critical milestone for cardiac arrest survivors, although the duration of coma can vary significantly. For this purpose, Jonathan Tam, Iroquois Building, Pittsburgh, PA, USA, and colleagues investigated the relationship between coma duration, short-term functional recovery, and long-term survival following cardiac arrest.

For this purpose, the researchers conducted a retrospective cohort study focusing on post-cardiac arrest patients who were comatose upon presentation but regained consciousness during hospitalization. They collected data on demographics, arrest characteristics, time from arrest to awakening, and the modified Rankin Scale (mRS) at discharge. Functional outcomes at discharge were compared between patients with shorter and longer coma durations, using median, 3-day, and 6-day cutoffs for classification.

Long-term survival was also analyzed among those who survived to discharge, stratified by coma duration. To further evaluate the relationship between coma duration and survival, Cox regression models were applied, adjusting for patient and arrest-related variables.

The study led to the following findings:

• A total of 979 subjects were included, with a median coma duration of 2 days.
• Shorter coma duration was linked to more patients achieving a discharge-modified Rankin Scale (mRS) score of ≤3.
• Among 742 subjects who survived to discharge, observed over 3,136 person-years, no significant difference was found in long-term survival between short and long coma durations.
• After adjusting for factors such as age, arrest location, Charlson Comorbidity Index, and discharge mRS, coma duration was not associated with the hazard of death (HR 1.00).

"Our findings showed that shorter coma duration was linked to better functional outcomes at hospital discharge in patients resuscitated from cardiac arrest. However, favorable recoveries were observed across all coma durations, and no association was found between coma duration and long-term survival," the researchers wrote.

"These results underscore the potential for recovery and long-term survival in cardiac arrest survivors, irrespective of coma duration," they concluded.

Reference:

Tam J, Case N, Coppler P, Callaway C, Faiver L, Elmer J; University of Pittsburgh Post-Cardiac Arrest Service. Impact of coma duration on functional outcomes at discharge and long-term survival after cardiac arrest. Resuscitation. 2024 Nov 30:110444. doi: 10.1016/j.resuscitation.2024.110444. Epub ahead of print. PMID: 39622450.