Alcohol, central nervous system injury, and time to death in fatal motor vehicle crashes

Objectives: Motor vehicle crash (MVC) studies have found that alcohol (ALC) is associated with increased mortality and decreased time to death (TTD). Clinical and experimental data suggest that ALC potentiates central nervous system injury (CNSI). We hypothesize that ALC-intoxicated, MVC fatalities with CNSI are more likely to die in the immediate postinjury period than are sober victims with CNSI. Methods: Design-A retrospective cohort of 401 MVC fatalities from four Michigan counties for the time period 1985 to 1991 was studied. Measurements-Medical examiner records were reviewed to determine age, blood alcohol concentration (BAC), and TTD. Injury severity was calculated with the Abbreviated Injury Scale (1985 version). Anatomical profile scores and G scores were also calculated and used to identify CNSI subjects. Analysis-chi(2) and Student's t test were used, and odds ratios with 0.95 confidence intervals (CIs) were calculated. Results: ALC(+) cases (BAC greater than or equal to 100 mg/dl) (n = 99) were significantly younger and more frequently had TTD < 1 hr than ALC(-) cases (n = 233): odds ratio 1.62 [0.95 CI (1.02 to 2.56)]. Overall, CNSI cases (n = 297) were significantly younger and had fewer thoracic injuries, but did not have significantly shorter TTD, compared with non-CNSI cases. However, ALC(+) CNSI cases (n = 77) were over twice as likely to have TTD < 1 hr {odds ratio 2.04 [0.95 CI (1.13 to 3.70)]}. For ALC(+) isolated CNSI cases, the odds ratio for TTD < 1 hr, compared with nonisolated CNSI cases was 8.25 (0.95; CI 0.66 to 102.5). Injury Severity Score, anatomical profile, and G scores were not significantly different for ALC(+) CNSI cases, compared with ALC(-) CNSI cases, whether isolated or nonisolated. Conclusions: These data suggest that alcohol intoxication is associated with increased frequency of early death in MVC victims with CNSI, despite there being no detectable difference in anatomical injury scoring.