Executive summary

A sample of 300 injecting drug users (IDU) from the greater Sydney region were interviewed regarding drug driving. Specifically, the study examined the prevalence and frequency of drug driving, drug-related motor vehicle accidents, predictors of drug driving, and risk perceptions of drug driving among IDU.

Driving histories
The overwhelming majority of the sample (95%) had driven a vehicle, and 74% had driven in the previous 12 months. There was no difference between the proportions of males and females who were current drivers.

Drug driving history
Of those who had ever driven, 87% reported having driven soon after using drugs (“drug driving”), representing 83% of the total sample. Of current drivers, 87% reported drug driving in the previous 12 months, representing two thirds of the total sample. Fifty nine percent of current drivers reported having drug driven in the preceding month (44% of the total sample). There were no significant sex differences in drug driving prevalence.

The most common drugs used before driving in the preceding year were: cannabis (57%), heroin (56%), amphetamines (34%), cocaine (33%) and other opioids (32%). Of those who had driven in the previous 12 months, 22% reported having driven soon after using heroin on at least a weekly basis, and 21% reported having driven soon after using cannabis on at least a weekly basis. The most common reasons given for drug driving were: to get home after “scoring drugs” (28%), to get around (26%), to give others a lift (11%) and to “score drugs” (11%). Drug driving whilst carrying passengers was reported by the majority of drivers (88%), with 77% of current drivers reporting having drug driven with passengers in the previous 12 months.

Drug-related vehicle accidents
One third of drivers (32%) reported having had an accident while drug driving, with a higher proportion of males reporting having done so (36% v 24%). One in ten current drivers (9%) reported having had an accident while drug driving in the previous year. The most common drugs used before the last drug driving accident were heroin (53%), cannabis (46%) and alcohol (42%). The mean number of drugs used preceding that accident was 2.1.

Fifteen percent of drivers reported having been injured in an accident while drug driving, and 8% reported that another person had been injured. Almost half (47%) of those who had ever had a drug driving accident reported having been injured in one of these accidents, and 25% reported that another person had been injured in one of these drug driving accidents.

Experience as a passenger of a drug driver
The majority of respondents (89%) had been a passenger of a drug driver, with 30% having done so weekly or more often over the previous 12 months. Forty two percent of respondents had been involved in a vehicle accident whilst being driven by a drug driver, and one in ten (12%) had been involved in such an accident in the previous 12 months. Overall, 17% of respondents who had been a passenger of a drug driver in the preceding year had been involved in an accident.

Risk perceptions of drug driving
Alcohol was perceived by IDU to be the most dangerous substance in terms of driving performance, perceived to be “very dangerous” by 84% of respondents. The next most dangerous drugs were hallucinogens (71%) followed by benzodiazepines (68%) and heroin. The drug perceived as least dangerous was cannabis (perceived as very dangerous by 18%), followed by amphetamines (31%) and cocaine (37%).

There were differences in the perceived danger of drug driving according to whether or not the respondent had driven after using drugs in the previous 12 months. Generally, drug drivers perceived drug driving to be less dangerous than other IDU. Specifically, drug drivers reported significantly lower levels of danger than other IDU for heroin, opioids, cocaine and cannabis.

Forty one percent of the sample perceived it to be likely that they would be caught for drug driving, with no significant sex differences in this perception. Drug drivers perceived the risk of getting caught as lower than other IDU.

Factors associated with drug driving
There were differences between drug drivers and other IDU according to their drug use patterns. Drug drivers had higher levels of dependence on their drug of choice, higher frequency of drug use and more extensive polydrug use. Drug use locations were related to drug driving. Drug-drivers were significantly more likely to have used a drug in the car in the previous 12 months, and to have injected in a car in the previous 12 months.

Drug drivers had driven significantly more frequently in the preceding 12 months than other drivers. Overall, the picture of a drug driver is of a heavily dependent polydrug user, who also drives frequently. Thus, if someone is using a drug frequently, and is also driving frequently, they will be more likely to drug drive, particularly if drugs are used in cars.

There were no significant age or sex differences between those who had driven after using drugs in the previous 12 months and those who had not. Drug-drivers were also not differentiated according to geographical region, with high proportions of IDU drug-drivers in the inner, middle and outer areas of Sydney.

There were no significant differences between drug drivers and other IDU in General Health Questionnaire (GHQ) scores, or the proportions meeting criteria for Borderline Personality Disorder or Antisocial Personality Disorder. Drug driving does not appear to be related to psychological distress, or to personality disorder.

It is apparent that drug driving is a significant issue for IDU, with a high risk of injury from drug-related vehicle accidents. Drug driving is an illegal behaviour, and the current data indicate it is a significant issue for other road users and the police. Education campaigns could be directed at IDU in order to reduce drug driving prevalence. Such interventions should attempt to alter the risk perceptions of IDU, informing users of the risks of drug driving and the risk of being a passenger of a drug driver. The use of public transport should also be encouraged.

Citation: Darke, S., Kelly, E. and Ross, J. (2003), Drug use and driving among injecting drug users, Sydney: National Drug and Alcohol Research Centre.