title: The impact of substance abuse on mortality in patients with severe traumatic brain injury.
abstract: BACKGROUND
  Drug and alcohol use are common in neurotrauma patients. Despite growing methamphetamine use there are few studies of the impact of methamphetamine use on outcome after traumatic brain injury (TBI).
  
  
  METHODS
  We conducted a retrospective review of 5-years of data from a trauma database. Inclusion criteria included severe TBI and diagnosis codes indicating head injury. The entire database was analyzed and then a subset of patients with complete toxicology data were examined separately. Primary outcome was mortality.
  
  
  RESULTS
  Four hundred eighty-three patients were included. Toxicology results were available for 52.6% of patients. Alcohol, amphetamines, and cannabis were the most commonly detected substances. Overall mortality was 50.9%. When the group with complete tox screen data were analyzed, a toxicology screen that was positive for alcohol or amphetamine was associated with decreased mortality with an odds ratio of 0.23 (CI: 0.10-0.56, p = 0.001) and 0.25 (CI: 0.08-0.79, p = 0.02), respectively. When the subset of patients for whom toxicology data were available was analyzed the amphetamine-positive group was more likely to use cannabis and less likely to use alcohol.
  
  
  CONCLUSIONS
  We unexpectedly found alcohol and methamphetamine use to be associated with decreased mortality. Neurotoxic and possible neuroprotective mechanisms of these substances are discussed as well as possible interactions between cannabis and methamphetamine. The potential influence of psycho-social factors are also considered. Prospective studies are needed to further investigate the effects of drug and alcohol use on outcome after severe TBI.
authors.affiliation: Queen's Medical Center Neuroscience Institute, Honolulu, Hawaii 96813, USA. kophelan@queens.org
authors.forename: Kristine
authors.initials: K
authors.lastname: O'Phelan
authors.forename: David L
authors.initials: DL
authors.lastname: McArthur
authors.forename: Cherylee W J
authors.initials: CW
authors.lastname: Chang
authors.forename: Deborah
authors.initials: D
authors.lastname: Green
authors.forename: David A
authors.initials: DA
authors.lastname: Hovda
mesh_terms: D000328:Adult; D000367:Age Factors; D001930:Brain Injuries / Q000401:mortality* / Q000523:psychology*; D016208:Databases, Factual; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D019966:Substance-Related Disorders / Q000150:complications* / Q000401:mortality; D015599:Trauma Severity Indices