Restraint use and risky driving behaviors across drug types and drug and alcohol combinations for drivers involved in a fatal motor vehicle collision on U.S. roadways.

Chang Liu,Yanlan Huang,Joyce C Pressley

doi:10.1186/s40621-016-0074-7

Abstract

BackgroundWhile driving impaired is a well-recognized risk factor for motor vehicle (MV) crash, recent trends in recreational drug use and abuse may pose increased threats to occupant safety. This study examines mechanisms through which drug and/or alcohol combinations contribute to fatal MV crash.MethodsThe Fatality Analysis Reporting System (FARS) for 2008–2013 was used to examine drugs, alcohol, driver restraint use, driver violations/errors and other behaviors of drivers of passenger vehicles who were tested for both alcohol and drugs (n = 79,932). Statistical analysis was based on Chi-square tests and multivariable logistic regression. Associations of restraint use and other outcomes with alcohol and drug use were measured by estimated odds ratios (ORs) and 95 % confidence intervals (95 % CIs).ResultsMore than half (54.8 %) of the study population were positive for drugs or alcohol at the time of crash. Approximately half of drivers were belted, but this varied from 67.1 % (unimpaired) to 33.0 % (drugs plus alcohol). Compared to the unimpaired, the odds of a driver being unbelted varied: alcohol and cannabis (OR 3.70, 95 % CI 3.44–3.97), alcohol only (3.50,3.36–3.65), stimulants (2.13,1.91–2.38), depressants (2.09,1.89–2.31), narcotics (1.84,1.67–2.02) and cannabis only (1.55,1.43–1.67). Compared to belted drivers, unbelted drivers were over 4 times more likely to die. Driving violations varied across drug/drug alcohol combinations. Speed-related violations were higher for drivers positive for stimulants, alcohol, cannabis, and cannabis plus alcohol, with a more than two fold increase for alcohol and cannabis (2.36, 2.05, 2.71).ConclusionsMechanisms through which drugs, alcohol and substance combinations produce increased risks to occupant safety include lowered restraint use and increases in risky driving behaviors, including speeding, lane, passing, turning and signal/sign violations.

Highlights

While driving impaired is a well-recognized risk factor for motor vehicle (MV) crash, recent trends in recreational drug use and abuse may pose increased threats to occupant safety
The major findings of this study indicate that specific drug classes and drug and alcohol combinations are associated with different patterns of driving violations among drivers involved in fatal crashes
This study extends the work of previous authors by examining and quantifying behaviors associated with fatal motor vehicle crashes including restraint use, speeding, passing and other violations across drug and drug categories (Timby et al 1998; Longo et al 2000)

Summary

Introduction

While driving impaired is a well-recognized risk factor for motor vehicle (MV) crash, recent trends in recreational drug use and abuse may pose increased threats to occupant safety. This study examines mechanisms through which drug and/or alcohol combinations contribute to fatal MV crash. The contribution of alcohol to motor vehicle crash risk has long been recognized (Maull et al 1984; Soderstrom et al 1993; Quinlan et al 2005), but the mechanisms through which various drugs and drug combinations contribute to serious MV crash are less well understood. While other studies in Europe and Australia suggest that the risk of causing motor vehicle crashes may differ from drug to drug (Mura et al 2003; Drummer et al 2004; Giovanardi et al 2005), the mechanisms through which this occurs have not been well elucidated

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