Question

Abstract 4. Association of Alcohol With Mortality After Traumatic Brain Injury

Jennifer S Albrecht, Majid Afshar,Deborah M Stein, Gordon S Smith. American Journal of Epidemiology, Volume 187, Issue 2, 1 February 2018, Pages 233–241,

Abstract

Although alcohol exposure results in reduced mortality after traumatic brain injury (TBI) in animal models, clinical trials based on proposed mechanisms have been disappointing and have reported conflicting results. Methodological issues common to many of these clinical studies may have contributed to the spurious results. Our objective was to evaluate the association between blood alcohol concentration (BAC) and in-hospital mortality after TBI, and overcome methodological problems of prior studies. We conducted a retrospective cohort study on individuals treated for isolated TBI (n = 1,084) at the R Adams Cowley Shock Trauma Center (Baltimore, Maryland) from 1997 to 2012. We excluded individuals with injury to other body regions and examined multiple cutpoints of BAC. Our primary outcome was in-hospital mortality. In adjusted logistic regression models, the upper level of each blood alcohol categorization from 0.10 g/dL (odds ratio = 0.63, 95% confidence interval: 0.40, 0.97) through 0.30 g/dL (odds ratio = 0.25, 95% confidence interval: 0.08, 0.84) was associated with reduced risk of mortality after TBI compared with individuals with undetectable BAC. In sensitivity analyses among individuals without penetrating brain injuries (95% firearm-related) (n = 899), the protective association was eliminated. This study provides evidence that the observed protective association between BAC and in-hospital mortality after TBI resulted from bias introduced by inclusion of penetrating injuries

Which of the following statements is correct?

a	In the main analysis, higher blood alcohol levels are associated with more protective effects against mortality compared with lower levels
b	The confidence interval for the OR for mortality in those with penetrating brain injury includes 1

c	Results of this study show that alcohol is protective against mortality in the absence of penetrating brain injury

Answer 1

It is given that, compared to patients with undetectable BAC the OR of upper level of blood alcohol categorization from 0.10 g/dL (odds ratio = 0.63, 95% confidence interval: 0.40, 0.97) through 0.30 g/dL (odds ratio = 0.25, 95% confidence interval: 0.08, 0.84) is decreasing indicating that as the BAC increases it is highly protective for TBI.

Therefore, the answer is

a) In the main analysis, higher blood alcohol levels are associated with more protective effects against mortality compared with lower levels