Drug and Driving: A Compendium of Research Studies

Annotated Sources (cont'd)

Canada

19. Adlaf, E.M., Mann, R.E. and Paglia, A. (2003)

Drinking, cannabis use and driving among Ontario students. Canadian Medical Association Journal 168: 565-566.

Overview

Self-report survey of drug use and driving among Ontario students

Type of study, population(s) and proportion tested
  1. 1,846 students in grades 7 to 13 in Ontario
  2. 1,119 students in grades 10 to 13 with a driver’s licence
  3. 508 students in grades 10 to 13 with a driver’s licence
Drugs examined (threshold values for detection)
  • Cannabis
  • Alcohol
Method of testing and medium used

Ontario Students Drug Use Survey -- self-report survey

  1. How often in the past 12 months have you ridden in a vehicle with a drinking driver?
  2. How often in the past 12 months have you driven with one hour of having two or more drinks?
  3. How often in the past 12 months have you driven within an hour of using marijuana?
Other dependent variables
Findings (including statistical methods)
  1. 31.9% -- increased with grade (17.5% in grade 7; 43.4% in grade 13)
  2. 15.1% -- 20% male 8.9% female -- higher among those in grades 12 and 13
  3. 19.7% drove after using marijuana -- 24.5% among males; 13.7% females

20. Beirness, D.J., Simpson, H.M. and Desmond, K. (2003)

The Road Safety Monitor 2002. Drugs and Driving. Ottawa: Traffic Injury Research Foundation.

Overview

Telephone survey of drug use and driving among population of Canadian drivers

Type of study, population(s) and proportion tested

N=1,214 Canadian drivers age 16+

Random telephone survey

Drugs examined (threshold values for detection)
  • Prescription drugs
  • Cannabis
  • Over-the-counter drugs
  • Illegal drugs
Method of testing and medium used

Self-reported use and driving

Other dependent variables

Driving after drinking

Findings (including statistical methods)
  • 17.7% reported driving after using potentially impairing drugs past 12 months
  • 2.3% prescription drugs
  • 15.9% OTC drugs
  • 1.5% cannabis
  • 0.9% other illegal drugs

Males under 30 most likely to drive after drug use

One-third of those reporting driving after cannabis also reported driving after drinking

21. Beirness, D.J., Simpson, H.M. and Desmond, K. (2004).

The Road Safety Monitor 2004. Drinking and Driving. Ottawa: Traffic Injury Research Foundation.

Overview

Telephone survey of drug use and driving among population of Canadian drivers

Type of study, population(s) and proportion tested

N=1,214 Canadian drivers age 16+

Random telephone survey

Drugs examined (threshold values for detection)
  • Cannabis
  • Alcohol
Method of testing and medium used

Self-report

Other dependent variables
Findings (including statistical methods)

2.1% reported driving after using cannabis

Increase from 1.5% two years ago

44% also reported driving after drinking

Most common among males < 30 years of age

22. Boase, P., Dawson, N. and Mann, R. (2004)

Cannabis and road safety in Canada: Summary of information on cannabis found in drivers & recent legislative developments. In: J. Oliver, P. Williams and A. Clayton (Eds.) Proceedings of the 17th International Conference on Alcohol, Drugs and Traffic Safety (CD). Glasgow: Scottish Executive.

Overview

Review of cannabis use and driving in Canada

Type of study, population(s) and proportion tested

Various
Review of survey literature

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

Self reported cannabis use
Self reported driving after cannabis use

Other dependent variables
Findings (including statistical methods)

Prevalence of use has increased

Prevalence of driving after cannabis use currently 1.9% to 2.1%

Higher among students and appears to be increasing

23. Bramness, J. G., Skurtveit, S., and Mørland, J. (2002)

Clinical impairment of benzodiazepines – Relation between benzodiazepine concentration and impairment in apprehended drivers. 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

Assessment of clinical impairment of benzodiazepine positive drivers in Norway

Type of study, population(s) and proportion tested

Drivers, suspected of driving under the influence between 1987 and 1998, positive for only one benzodiazepine (n=818)

Comparison group of drivers positive only for alcohol in 1987 (n=10,759)

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

Blood samples
Clinical Test for Drunkenness (CTD)

Other dependent variables
Findings (including statistical methods)

Within the benzodiazepine group, 81% were "impaired"

"Impaired" drivers had significantly higher concentrations of diazepam and oxazepam

Within the alcohol group, 91% were "impaired"

OR for being determined "impaired" significantly rose as dose increased from therapeutic to mildly elevated (1.6), to moderately elevated (3.7), to highly elevated (4.1)

Same trend is true for alcohol group, though a greater OR was found for the highly elevated dose (10.5)

24. Centre for Addiction and Mental Health (2003)

Cannabis Use and Driving Among Ontario Adults. Population Studies eBulletin, No. 20, May/June 2003.

Overview

Telephone survey of Ontario residents about cannabis use and driving after using cannabis

Type of study, population(s) and proportion tested

Results from 2002 CAMH Monitor and 86/97 Ontario Drug Monitor

Both are telephone surveys

Drugs examined (threshold values for detection)
  • Self-reported cannabis use and driving after cannabis use
Method of testing and medium used
Other dependent variables
Findings (including statistical methods)

Cannabis use: 11.4% (10.0 - 13.0) at least once in previous 12 months

Males 15.1% Females 7.9%

18 - 34 22% >55 3%

Among drivers 2.9% (2.1 - 4.0) drove within 1 hour of cannabis use in the past 12 months

Males 4.7% Females 1.0%

Increase from 1.9% in 96/97

25. Chipman, M.L., Macdonald, S., and Mann, R.E. (2003).

Being "at fault" in traffic crashes: does alcohol, cannabis, cocaine, or polydrug abuse make a difference? Injury Prevention 9: 343-348.

Overview

Historical cohort study of crash rates among drug users in treatment

Type of study, population(s) and proportion tested

Subjects beginning treatment at CAMH in Toronto for alcohol, cannabis, of cocaine abuse in 1994

n=590 (411 drivers)

Control: 518 matched drivers

Drugs examined (threshold values for detection)
  • Cocaine
  • Cannabinoids
  • Alcohol
  • Combinations thereof
Method of testing and medium used

Secondary data analysis; no drug testing involved

Other dependent variables

Crashes per 100 person-years at risk

Traffic convictions per 100 person-years at risk

Findings (including statistical methods)

Poisson regress to control for variations in time at risk, age, sex

Adjusted RR: higher pre-treatment than post-treatment
No difference between treatment and control post treatment
Higher for at-fault crashes

Comments

Implication is that among the treatment group high pre-treatment crash levels are a consequence of driving under the influence of drugs but there is no evidence that this is so

26. Dussault, C; Lemire, AM; Bouchard, J; and Brault. M. (2000)

Drug use among Quebec drivers: The 1999 roadside survey. In: Proceedings of the 15th International Conference on Alcohol, Drugs & Traffic Safety. May 22-26, 2000. Stockholm, Sweden: International Council on Alcohol, Drugs & Traffic Safety.

Overview

Report on the 1999 roadside alcohol and drug survey in Quebec

Type of study, population(s) and proportion tested

Random roadside survey in Quebec

N=5,509 day and night, month of August

95.9% provided a breath sample for alcohol

41.4% provided a urine sample; of those who refused, 70.1% provided saliva
overall, 82.5% provided either urine or saliva for drug analysis

Drugs examined (threshold values for detection)
  • Cocaine (300 ng/100ml)
  • Cannabinoids (25/ng/100ml)
  • Alcohol (20mg/100ml)
  • Benzodiazipines (50ng/100ml)
  • Opiates (100 ng/100ml)
  • Barbiturates (200 ng/100ml)
  • Amphetamines (300ng/100ml)
  • PCP (25 ng/100ml)
Method of testing and medium used

Breath for alcohol
Urine and/or saliva for drugs
Positive urine screen for drugs confirmed by GC/MS

Other dependent variables

Age, sex

Findings (including statistical methods)

Alcohol:

  • 0.8% > 80 mg% (24 hours)
  • 1.8% > 80 mg% (Wed to Sat 9 pm to 3 am)
  • (1981 result was 5.9%)

Urine tests:

  • Cannabis 5.22% (declines with age)
  • Benzodiazepines 3.66% (increases with age)
  • Cocaine 1.09%
  • Opiates 1.08%
  • Barbiturates 0.35%
  • Amphetamines 0.07%
  • PCP 0.03%

Large variation according to age, sex and time of day
Illicit drug use greater among men than women
Prescription drugs more common among women than men

Comments

This is part of a larger case-control study in Quebec. This is the first year of the roadside survey results. Data collection will continue in the following year. The roadside data (controls) will be compared with results from fatally injured drivers (cases)

27. Dussault, C., Brault, M., Bouchard, J. and Lemire, A.M. (2002)

The Contribution of Alcohol and Other Drugs Among Fatally Injured Drivers in Quebec: Some Preliminary Results. 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

This is a case-control study comparing drug and alcohol use among fatally injured drivers (cases) with that among a random sample of drivers on the road (controls)

Type of study, population(s) and proportion tested

Case-control study in the province of Quebec. Alcohol testing > 95%; urine (for drugs) 41%

Drugs examined (threshold values for detection)
  • Thresholds (urine, blood) ng/100ml
  • Cocaine (300, 100)
  • Cannabinoids (25, 40)
  • Benzodiazipines (50, 25)
  • Opiates (100, 50)
  • Barbiturates (200, 200)
  • Amphetamines (300, 200)
  • PCP (25, 10)
Method of testing and medium used

Roadside - urine (breath for alcohol)

Fatalities - blood/serum

Other dependent variables

Only included cases and controls for which both biological samples were obtained (i.e., breath & urine for controls; blood & urine for cases)

Matched for 354 cases

Findings (including statistical methods)

Based on urine

Drug Case/Control OR Responsibility Analysis OR
Alcohol 51-80 3.7 (1.6 - 8.3) 1.6 (0.2 - 1.5)
> 80 39.2 (25.5 - 60.2) 8.1 (1.0 - 34.8)
Cannabis 2.2 (1.5 - 3.4) 1.2 (0.4 - 3.9)
(with alcohol < 80) 80.5 (28.2 - 230.2) 2.5 (0.3 - 20.2)
Cocaine 4.9 (1.4 - 17.4)  
Benzodiazepines 2.5 (1.4 - 4.3) 3.6 (0.5 - 28.2)

Drug Cases (%) Controls (%)
Alcohol 35 5.1
Cannabis 19.5 6.7
Cocaine 6.8 1.1
Benzodiazipines 8.5 3.6
Opiates 1.4 1.2
Amphetamines 0.8 0.1
Barbiturates 0.3 0.5
PCP 1.1 0.03

Alcohol found in > 40% of drug cases; drugs found in 35% of alcohol cases

Comments

Testing rate 41.1% for urine in controls

Case results based on urine -- indicative of use but not impairment

28. Hemmelgarn, B., Suissa, S., Huang, A., Boivin, J., and Pinard, G. (1997).

Benzodiazepine use and the risk of motor vehicle crash in the elderly. Journal of the American Medical Association 278(1): 27-31.

Overview

Case-control study of benzodiazepine and crashes in Quebec

Type of study, population(s) and proportion tested

67 to 84 year old drivers who were involved in a crash where at least one person was injured (5579 cases)

Controls were random sample selected from the cohort (18,490 controls)

Cohort time was June 1, 1990 to May 31, 1993

Drugs examined
  • Benzodiazepines:
  • Long elimination (> 24 hours)
  • Short-elimination (≤ 24 hours)
Method of testing and medium used

Prescription drug use was identified from computerized files from the Regie de l’assurance maladie du Quebec (agency responsible for administering health care services for the province)

Other dependent variables

Sex, age, region, and history of crashes (two years before entry into cohort)

Findings (including statistical methods)
  • Current use of benzodiazepines, irrespective of duration of use, was 7% for cases and 5% for controls
  • Increased risk of traffic crash associated with current use of long half-life benzodiazepines (RR=1.28)
  • Within first 7 days of initiating treatment, RR=1.45
  • Continued use lasting from 61 to 365 days, RR=1.26

29. Jeffery, W.K., Hindmarsh, K.W. and Mullen, P.W. (1996)

The involvement of drugs in driving in Canada: An update to 1994. Canadian Society of Forensic Sciences Journal 29: 93-98.

Overview

Presents the toxicological results of cases submitted to Forensic Laboratories in Canada

Type of study, population(s) and proportion tested

All cases -- impaired driving and fatally injured drivers -- submitted to forensic laboratories in Canada for drug testing through November 1994

  • N=1158 cases
  • N=767 impaired drivers
  • N=391 fatalities (presumably drivers)
Drugs examined (threshold values for detection)
  • Cannabinoids
  • Alcohol
  • Benzodiazepines
  • Stimulants
  • Opiates
  • Others
Method of testing and medium used

Not stated

Other dependent variables
Findings (including statistical methods)
  Impaired drivers Fatalities
Alcohol <100 mg/dL 32% 18%
=100 mg/dL 19% 30%
zero 49% 52%
Benzodiazepines 66.0% 21.4%
Cannabis 40.2% 62.1%
Stimulants 21.8% 14.5%
Opiates 18.8% 8.2%
Barbiturates 15.5% 3.1%

Alcohol was present in the majority of cannabis positive cases

Comments

Selection of the sample is unknown -- presumably there had to be a suspicion of drug and/or alcohol use for case to be submitted

Test for drugs not usual when BAC ≥100 mg/dL

Cases testing negative for drugs not reported

30. Mann, R.E., Brands, B., Macdonald, S. and Stoduto, G. (2003)

Impacts of cannabis on driving: an analysis of current evidence with an emphasis on Canadian data. Report TP 14179E. Ottawa: Transport Canada.

Overview

Review of cannabis use and driving

Type of study, population(s) and proportion tested

Literature review

Drugs examined (threshold values for detection)

Cannabis

Method of testing and medium used

Six areas considered in report:

  1. Experimental research on effects of cannabis
  2. Prevalence of cannabis use
  3. Prevalence of driving under the influence of cannabis
  4. Epidemiological studies on collision risk
  5. Methods for assessing cannabis in drivers
  6. Legal initiatives
Other dependent variables
Findings (including statistical methods)
  1. Moderate to high dose considered to impaired performance
  2. Most widely used psychoactive drug in Canada -- 33% lifetime, 7.3% past year
  3. Use by drivers 1.5% to 1.9% -- among young drivers 19.3%
  4. Most common drug found among fatal and injured drivers 13.9% to 19.5%
    Difficult to determine collision risk -- data and methodological problems
  5. Blood test is the gold standard for determining cannabis level. Saliva,
    sweat and behavioural measures show promise
  6. Currently driving impaired by alcohol or drug is an offence

31. Mercer, G. W., and Jeffery, W. K. (1995)

Alcohol, drugs, and impairment in fatal traffic accidents in British Columbia. Accident Analysis and Prevention, 27(3): 335-343.

Overview

Study of fatally injured drivers in British Columbia

Type of study, population(s) and proportion tested

227 fatally injured drivers who died within 24 hours of a traffic accident in British Columbia

Time period of October 1, 1990 to September 31, 1991

Drugs examined
  • Alcohol
  • Specific list of drugs not given
  • Reported cannabinoids, cocaine, and CNS depressants
Method of testing and medium used

Blood sample

Other dependent variables
  • Number of vehicles
  • Time of day
  • Day of week
  • Age
Findings (including statistical methods)
  • 48% positive for alcohol, 37% alcohol only
  • 13% positive for cannabinoids
  • 4% positive for cocaine (all male)
  • 5% positive for CNS depressant diazepam
  • 11% tested positive for both alcohol and drugs, 9% drugs only
  • Those positive for drugs and/or alcohol tended to be younger
  • Those positive for drugs and/or alcohol tended to be in collisions involving one vehicle
  • Those positive for drugs and/or alcohol tended to be in collisions at night and on weekends
Comments

Selection criteria for drivers tested not clear

32. Neutel, C. I. (1995)

Risk of traffic accident injury after a prescription for a benzodiazepine. Annals of Epidemiology 5: 239-244.

Overview

Case control study of benzodiazepine use and crash involvement

Population(s) and proportion tested (including type of study)

147,726 who received anxiolytics and 97,862 controls in Saskatchewan monitored for two months after the index prescription was filled for traffic accidents

Time period was 1979 to 1986
Drugs examined (threshold values for detection)

Benzodiazepines
Other drug histories (such as narcotics, alcohol, etc.)

Method of testing and medium used

Data obtained from the Health Insurance Registration File, Prescription Drug Plan, and Hospital Inpatient Data Base

Other dependent variables

Age, sex, year of prescription, concomitant use of other drugs, alcohol abuse, social welfare recipient

Findings (including statistical methods)

Those using hypnotics had a 3.9 increased risk of accidental injury compared to controls

Those using anxiolytics had a 2.5 increased risk of accidental injury compared to controls

Using a window of 2 weeks, RR’s increased to 6.5 and 5.6

Concomitant use of other drugs with sedative actions doubled the risk of accidents

Comments

Benzodiazepine use was not measured in crash involved drivers

33. Stoduto, G., Vingilis, E., Kapur, B. M., Sheu, W., McLellan, B. A., and Liban, C. (1993)

Alcohol and drug use among motor vehicle collision victims admitted to a regional trauma unit: Demographic, injury, and crash characteristics. Accident Analysis and Prevention 25(4): 411-420.

Overview

Study of traffic crash victims admitted to trauma centre in Toronto

Type of study, population(s) and proportion tested

854 seriously injured motor vehicle collision victims admitted to trauma unit in Toronto (drivers and passengers)

Time period of August 1, 1986 to August 31, 1989

Drugs examined
  • Benzodiazepines
  • Cocaine
  • Cannabinoids
  • Opiates
  • Alcohol
Method of testing and medium used

Blood samples for alcohol and additional blood and urine samples for drugs

Other dependent variables

Sex, age, occupant status, admission type, elapsed time from collision, injury severity, and crash variables (seatbelt usage, type of crash, speed, ejection)

Findings (including statistical methods)

Of the 339 drivers analyzed for drugs and alcohol, 35% were positive for alcohol and 41% were positive for at least one drug other than alcohol

Prevalence of cannabinoids the highest (14%), then benzodiazepines (12%), then cocaine and morphine (both at 5%)

Greater percentage of positive BAC subjects in single-vehicle collisions, not using seatbelts, and ejected from vehicle

34. Walsh, G. and Mann, R.E. (1999)

On the high-road: Driving under the influence of cannabis in Ontario. Canadian Journal of Public Health 90: 260-263.

Overview

Random telephone survey of adult population of Ontario

Type of study, population(s) and proportion tested

N = 5,497 Ontario adults over two years
Response rates > 60%
Sub-sample of 4,735 with driver’s licence used to predict driving under the influence of cannabis

Drugs examined (threshold values for detection)
  • Cannabinoids
  • Alcohol
Method of testing and medium used
Other dependent variables
Findings (including statistical methods)

1.9% reported driving under the influence of cannabis (22.8% of users)

Logistic regression used to show prime risk was men, < 25, never or previously married, without a college degree

47% of those who reported driving under the influence of cannabis also reported driving after drinking

Date modified: