Effect of alcohol on Glasgow Coma Scale in head-injured patients

OBJECTIVE: Almost 50% of traumatic brain-injured (TBI) patients are alcohol intoxicated. The Glasgow Coma Scale (GCS) is frequently used to direct diagnostic and therapeutic decisions in these patients. It is commonly assumed that alcohol intoxication reduces GCS, thus limiting its utility in intoxicated patients. The purpose of this study was to test the hypothesis that the presence of blood alcohol has a clinically significant impact on GCS in TBI patients. METHODS: The National Trauma Data Bank of the American College of Surgeons was queried (1994-2003). Patients 18 to 45 years of age with blunt injury mechanism, whose GCS in the emergency department, survival status, anatomic severity of TBI (Head Abbreviated Injury Score [AIS]), and blood alcohol testing status were known, were included. GCS of patients who tested positive for alcohol (n = 55,732) was compared with GCS of patients who tested negative (n = 53,197), stratified by head AIS. RESULTS: Groups were similar in age (31 +/- 8 vs. 30 +/- 8 years), Injury Severity Score (ISS; 12 +/- 11 vs. 12 +/- 11), systolic blood pressure in the ED (131 +/- 25 vs. 134 +/- 25 mm Hg), TRISS (Trauma Injury Severity Score; probability of survival (94% +/- 16% vs. 95% +/- 15%), and actual survival (96% vs. 96%). When stratified by anatomic severity of TBI, the presence of alcohol did not lower GCS by more than 1 point in any head AIS group (GCS in alcohol-positive vs. alcohol-negative patients; AIS 1 = 13.9 +/- 2.8 vs. 14.3 +/- 2.3; AIS 2 = 13.4 +/- 3.2 vs. 14.1 +/- 2.4; AIS 3 = 11.1 +/- 4.7 vs. 11.6 +/- 4.6; AIS 4 = 9.8 +/- 4.9 vs. 10.4 +/- 4.9; AIS 5 = 5.5 +/- 3.8 vs. 5.9 +/- 4.1, AIS 6: 3.4 +/- 1.1 vs. 3.8 +/- 2.8). CONCLUSION: Alcohol use does not result in a clinically significant reduction in GCS in trauma patients. Attributing low GCS to alcohol intoxication in TBI patients may delay necessary diagnostic and therapeutic interventions.