title: Drugs and alcohol: their relative crash risk.
abstract: OBJECTIVE
  The purpose of this study was to determine (a) whether among sober (blood alcohol concentration [BAC] = .00%) drivers, being drug positive increases the drivers' risk of being killed in a fatal crash; (b) whether among drinking (BAC > .00%) drivers, being drug positive increases the drivers' risk of being killed in a fatal crash; and (c) whether alcohol and other drugs interact in increasing crash risk.
  
  
  METHODS
  We compared BACs for the 2006, 2007, and 2008 crash cases drawn from the U.S. Fatality Analysis Reporting System (FARS) with control drug and blood alcohol data from participants in the 2007 U.S. National Roadside Survey. Only FARS drivers from states with drug information on 80% or more of the drivers who also participated in the 2007 National Roadside Survey were selected.
  
  
  RESULTS
  For both sober and drinking drivers, being positive for a drug was found to increase the risk of being fatally injured. When the drug-positive variable was separated into marijuana and other drugs, only the latter was found to contribute significantly to crash risk. In all cases, the contribution of drugs other than alcohol to crash risk was significantly lower than that produced by alcohol.
  
  
  CONCLUSIONS
  Although overall, drugs contribute to crash risk regardless of the presence of alcohol, such a contribution is much lower than that by alcohol. The lower contribution of drugs other than alcohol to crash risk relative to that of alcohol suggests caution in focusing too much on drugged driving, potentially diverting scarce resources from curbing drunk driving.
authors.affiliation: Pacific Institute for Research and Evaluation, Calverton, Maryland.
authors.forename: Edurado
authors.initials: E
authors.lastname: Romano
authors.affiliation: Department of Mathematical Sciences, University of Puerto Rico at Mayagüez, Mayagüez, Puerto Rico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Torres-Saavedra
authors.affiliation: Pacific Institute for Research and Evaluation, Calverton, Maryland.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Voas
authors.affiliation: Pacific Institute for Research and Evaluation, Calverton, Maryland.
authors.forename: John H
authors.initials: JH
authors.lastname: Lacey
mesh_terms: D000063:Accidents, Traffic / Q000523:psychology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000428:Alcohol Drinking / Q000453:epidemiology* / Q000523:psychology; D001334:Automobile Driving / Q000523:psychology; D003625:Data Collection / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D015813:Substance Abuse Detection / Q000379:methods*; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D055815:Young Adult