Causes and outcome of coma: A nationwide cross-sectional analysis

The Neurocritical Care Society Curing Coma Campaign has renewed interest in coma management. Large-scale cross-sectional data on the relative frequency of coma etiologies and factors influencing survival remain limited.

We analyzed the National Inpatient Sample (NIS) database and extracted all cases of coma treated with mechanical ventilation (MV) between 2010 and 2019. A hierarchical classification system assigned each patient a primary coma etiology, prioritizing (1) major structural/cellular brain injuries, (2) laboratory-confirmed diagnoses, and (3) organ failure etiologies.

Of 1,904,453 MV admissions, 146,577 (7.6%) involved coma. Mortality was 47% in comatose versus 29% in non-comatose patients (P < 0.001); 30% of comatose patients who died had a do-not-resuscitate (DNR) order. The most common etiologies were cardiac arrest (20%), traumatic brain injury (17%) and intracerebral hemorrhage (ICH, 16%). Highest mortality occurred after cardiac arrest (75%), cardiogenic shock (71%), ICH (63%), subarachnoid hemorrhage (56%), AIS (51%), and hepatic coma (51%); lowest mortality was observed with drug overdose (13%). Multivariable analysis identified DNR status as the strongest mortality predictor (AOR 7.1), followed by high- (AOR 5.0) or intermediate-risk (AOR 1.7) primary diagnosis and age > 55 years (AOR 1.6; all P < 0.001). Non-white and Medicaid patients had lower mortality and were significantly less likely to carry a DNR order.

Almost half of comatose patients die in the hospital and 30% of these patients are DNR. Given withdrawal of life support is a major determinant of survival, better tools are needed to accurately predict neurological outcomes in disorders of consciousness.