Drug and Driving: A Compendium of Research Studies

Annotated Sources (cont'd)

Australia

10. Drummer, O. H. (1995)

Drugs and accident risk in fatally injured drivers. Proceedings of the 17th International Conference on Alcohol, Drugs and Traffic Safety (T’95). Australia.

Overview

Study of fatally injured drivers in Australia

Type of study, population(s) and proportion tested

1052 fatally injured drivers in Australia
Time period of January 1990 to December 1993

Drugs examined (threshold values for detection)
  • Benzodiazepines
  • Other prescription drugs
  • Drugs of abuse (including alcohol)
Method of testing and medium used

Blood samples
Those with drugs compared to those drug-free to obtain ORs

Other dependent variables
Findings (including statistical methods)

Drugs in 22% of cases (13% with drugs only and 9% in combination with alcohol)

Alcohol in 36% of cases

Illegal drugs in 13% of cases

Most common were cannabis (11%), and stimulants, benzodiazepines, and opiates (3% each)

Only OR that was significant was for alcohol (OR=7.6)

Those with higher than therapeutic concentrations or multiple drugs had more responsible cases

Comments

Selection of cases not specified

11. Drummer, O. H., Gerostamoulos, J. Batziris, H., Chu, M., Caplehorn, J., Robertson, M. D., and Swann, P. (2004)

The involvement of drugs in drivers of motor vehicles killed in Australian road traffic crashes. Accident Analysis and Prevention 36: 239-248.

Overview

Culpability analysis of fatally injured drivers in Australia

Type of study, population(s) and proportion tested

Drivers killed in motor vehicle crashes in 3 Australian states (VIC., NSW, and WA) (n=3398)

Only on-road crashes included:
Data from Coroner’s offices/Offices of Forensic Medicine, etc.
Cases not included if death was more than 4 hours from crash and if blood sample was not collected within 4 hours of the crash
Time period from 1990 to 1999

Drugs examined
  • Benzodiazepines
  • Opiates
  • Amphetamines
  • Cannabinoids (THC or carboxy-THC)
  • Other psychoactive
  • Non-psychoactive
  • Alcohol
Method of testing and medium used

Blood sample which was subjected to a full toxicological investigation

Other dependent variables

Responsibility analysis used to determine culpability – involved using the following information:

  • Condition of the road
  • Condition of the vehicle
  • Driving conditions
  • Type of crash
  • Witnesses’ observations
  • Road law obedience
  • Difficulty of task
  • Level of fatigue
Findings (including statistical methods)

Presence of alcohol - 29%; any type of drug - 27%; cannabinoids – 14%; opioids – 5%; stimulants – 4%; and benzodiazepines – 4%

Of the 1694 drug or alcohol- positive drivers, 88% were responsible for the crash (compared to 71% for those not positive)

Odds ratios for alcohol were from 1.2 (BAC <.05%) to 25 (BAC >.20%) and ORs for BAC’s above .10% all significant

Detection of any type of drug was significantly associated with culpability (OR=1.7)

Largest ORs associated with THC (6.6), stimulants (OR=2.3), and other psychoactive (OR=3.8)

OR for THC positive and BAC ≥ .05% was 2.9 times that for drivers with BAC ≥ .05% alone

Comments

65% of opiate-positive drivers were using other drugs, therefore, the exclusion of drivers who had taken other drugs reduced power of testing for an association between opiates and culpability

12. Gerostamoulos, J., McCaffrey, P., Drummer, O.H., Potter, J., Fitzgerald, M. and Odell, M. (2002)

Drug prevalence in road trauma victims in Victoria. In: D.R. Mayhew and C. Dussault (Eds) Proceedings of the 16th International Conference on Alcohol, Drugs and Traffic Safety. Quebec: Société de l’Assurance Automobile du Québec.

Overview

Report on persons injured in collisions in Victoria, Australia

Type of study, population(s) and proportion tested

N=358 (proportion tested not reported)

Drugs examined (threshold values for detection)
  • Cocaine
  • Cannabinoids
  • Opiates
  • Benzodiazepines
  • Amphetamines
Method of testing and medium used

Blood samples

Enzyme immunosorbent assay confirmed by chromatographic techniques

Other dependent variables
Findings (including statistical methods)
  • Cocaine 2%
  • Cannabinoids 36%
  • Opiates 10%
  • Benzodiazepines 14%
  • Amphetamines 12%
Comments

Few details provided

Not sure if sample consists of drivers or anyone reporting to hospital who was injured in a motor vehicle collision

13. Longo, M. C., Hunter, C. E., Lokan, R. J., White, J. M., and White, M. A. (2000).

The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability. Part I: The prevalence of drug use in drivers, and characteristics of the drug-positive group. Accident Analysis and Prevention 32: 613-622.

Overview

Study of injured drivers in South Australia

Type of study, population(s) and proportion tested

2500 injured drivers involved in a non-fatal road crash and survive for more than 30 days in South Australia

Time period of April to August 1995 and December to August 1996

Drugs examined (threshold values for detection)
  • Cannabinoids (40 ng/ml)
  • Benzodiazepines (5 ng/ml)
  • Stimulants (50 ng/ml)
  • Alcohol
Method of testing and medium used

Blood sample
Crash details obtained from police records

Other dependent variables
Findings (including statistical methods)

23% tested positive for at least one drug including alcohol, 10% excluding alcohol

Alcohol and cannabinoids most common

12% with positive BAC, 10% over legal (0.05%)

Cannabinoids in 11% of drivers

Drivers tended to be younger males

Drivers in single-vehicle collisions significantly more likely to test positive for drugs than those in multiple-vehicle collisions

14. Parliamentary Travelsafe Committee (1999)

Drug Driving in Queensland. Legislative Assembly of Queensland.

Overview

This review summarizes general findings about drug use among drivers in Queensland

Type of study, population(s) and proportion tested

Literature review

Drugs examined (threshold values for detection)
  • Cannabis
  • Narcotics
  • Opiates
  • Antidepressants
  • Stimulants
  • Alcohol
Findings (including statistical methods)

Threat to road safety posed by drug driving is significantly less than that for drink driving

Most frequently detected drugs in fatally injured drivers include:

  • Cannabis
  • Narcotic analgesics
  • Opiates
  • Antidepressants
  • Stimulants

Drugs commonly found with alcohol and other drugs

Relationship between drug use, impairment of driving and crash risk is not fully understood

Increased crash risk for drugs in combination with alcohol

Increased crash risk associated with benzodiazepine use as well as cannabis and stimulant use

The young and elderly are at-risk groups with the young more likely to use illegal and prescribed drugs for recreational purposes and the elderly more likely to use prescription drugs

Commercial drivers were highlighted in this review as a group that is more likely to use illegal and prescribed drugs more than any other road user group

Commercial drivers of particular concern with respect to their use of psychostimulant drugs to maintain alertness

15. Potter, J. (2000)

Drugs and Driving in Australia. Sydney: Austroads.

Overview

This review summarizes findings from Australian studies on the prevalence of drugs and the relative risks associated with drugged driving

Type of study, population(s) and proportion tested

Literature review

Drugs examined (threshold values for detection)
  • Licit drugs
  • Illicit drugs
  • Alcohol
Findings (including statistical methods)

Simply detecting drugs in various populations of drivers cannot allow for causation to be inferred

Many drugs, when detected, are detected in combination with alcohol

The relationship between drug concentration in the body and the risk of that driver crashing are not well understood

Cannabis, when detected alone, does not seem to significantly increase the risk of crash, however, when Delta-9-THC is found alone in high concentrations, elevated risk is observed (though number of cases is small)

Mediating factors of drug effects are illness, fatigue, and mood

Legislation dealing with drugs and driving should deal with the impairment of the driver and not on dose of drug

Roadside screening devices can be a valuable tool for assessing drugged drivers and the prevalence of certain drugs

16. Swann, P. (2000)

The real risk of being killed when driving whilst impaired by cannabis. In: Proceedings of the 15th International Conference on Alcohol, Drugs and Traffic Safety. May 22-26, 2000. Stockholm, Sweden. International Council on Alcohol, Drugs & Traffic Safety.

Overview

Australian studies, from 1995 to 1998, dealing specifically with cannabis prevalence among drivers, are discussed. Emphasis is placed on drivers where the only drug detected was the impairing constituent Delta-9-THC

Type of study, population(s) and proportion tested

Literature review

Drugs examined (threshold values for detection)
  • Cannabis
  • Psychotropic drugs
  • Delta 9-THC
Findings (including statistical methods)

Percent driving after using marijuana ranged from 7-22% in injured drivers and 8-37% in fatalities

Illicit drugs 15 times more common in impaired, injured, and fatally injured drivers than in general population

OR for psychotropic drugs was 3.8, drugs and alcohol, 9.2, and, specifically, Delta-9-THC, 6.4

Though small numbers were involved for those containing only the cannabis constituent Delta-9-THC, 24 of the 25 fatally injured drivers were deemed culpable

It is suggested that the concentration of 11 ng/ml of THC affects all performance areas, and, doses found in fatally injured drivers, who only had THC in their system, ranged from 38 ng/ml in 1995-1996 to 24 ng/ml in 1997-1998

Authors suggest that cannabis alone, in high doses, poses a relatively high risk to driving

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