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Drug and Driving: A Compendium of Research Studies
Annotated Sources (cont'd)
Canada (cont'd)
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)
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)
| 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) |
| 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:
- Experimental research on effects of cannabis
- Prevalence of cannabis use
- Prevalence of driving under the influence of cannabis
- Epidemiological studies on collision risk
- Methods for assessing cannabis in drivers
- Legal initiatives
Other dependent variables
Findings (including statistical methods)
- Moderate to high dose considered to impaired performance
- Most widely used psychoactive drug in Canada -- 33% lifetime, 7.3% past year
- Use by drivers 1.5% to 1.9% -- among young drivers 19.3%
- Most common drug found among fatal and injured drivers 13.9% to 19.5%
Difficult to determine collision risk -- data and methodological problems - Blood test is the gold standard for determining cannabis level. Saliva,
sweat and behavioural measures show promise - 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 1986Drugs 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
