Transport Research Series

Transcription

1 Transport Research Series Illicit Drugs and Driving Transport Research Planning Group

2 ILLICIT DRUGS AND DRIVING Katherine Myant Steven Hope MORI Scotland Prof James McIntosh Tommy O Brien Prof Neil McKeganey Centre for Drugs Misuse Research, University of Glasgow Prof Steve Stradling Transport Research Institute, Napier University Scottish Executive Social Research 2006

3 This report is available on the Scottish Executive Social Research website only The views expressed in this report are those of the researchers and do not necessarily represent those of the Department or Scottish Ministers. Crown Copyright 2006 Limited extracts from the text may be produced provided the source is acknowledged. For more extensive reproduction, please write to the Chief Researcher at Office of Chief Researcher, 4th Floor West Rear, St Andrew s House, Edinburgh EH1 3DG

4 CONTENTS EXECUTIVE SUMMARY 4 CHAPTER 1: INTRODUCTION AND BACKGROUND 6 CHAPTER 2: METHODOLOGY 8 CHAPTER 3: PREVALENCE AND TRENDS OF DRUG USE IN SCOTLAND 12 CHAPTER 4: PREVALENCE OF DRUG DRIVING 21 CHAPTER 5: EXPLANATIONS OF DRUG DRIVING AND ATTITUDES TOWARDS THE LAW 29 CHAPTER 6: OTHER DRIVING VIOLATIONS AND SENSATION SEEKING 36 CHAPTER 7: EXPERIENCES OF PASSENGERS 39 CHAPTER 8: DESISTANCE OF, AND PREVENTING DRUG DRIVING 42 CHAPTER 9: KEY FINDINGS AND RECOMMENDATIONS 46 ANNEX A 49

5 EXECUTIVE SUMMARY The Scottish Road Safety Campaign (the SRSC changed its name to Road Safety Scotland in October 2005 and the new title will be used throughout the remainder of this report) and the Scottish Executive commissioned a team comprising MORI Scotland, the Centre for Drugs Misuse Research at Glasgow University and Professor Steve Stradling of Napier University s Transport Research Institute to conduct research to investigate the prevalence and social context of drug driving. In particular, this research was aimed at providing the Scottish Executive and Road Safety Scotland with a deeper understanding of the incidence of drug driving and the context in which it occurs. The research consisted of a survey of year old drivers and qualitative interviews with problem drug users, recreational drug users and people who had been passengers of drug drivers. The key findings from the survey and interviews were: Over a third (39%) of the people interviewed said they had ever used drugs and 9% said they had done so in the previous twelve months. The ever figure is consistent with previous trends but the last twelve months figure is lower and suggests that this survey might be underestimating the prevalence of drug use among year old drivers. After considering the extent of any under-reporting it is estimated that up to 16% might have used drugs in the previous twelve months. Men were significantly more likely than women to have used drugs ever, and in the previous twelve months. Recent drug use was most common among year olds and year olds. Those who did not live with a partner were more likely to have used drugs in the previous twelve months. The majority of those who reported any drug use said that they had used cannabis and this use was fairly frequent. With regard to drug driving, 6% said they had ever driven within a period of using drugs when it was likely that they would have been impaired and 3.5% had done so in the previous twelve months. Again, the potential for under-reporting to have affected this was examined and it was estimated that up to 11% might ever have driven while impaired and up to 6% might have done so in the previous twelve months. The differences between this survey and the survey in 2000 whether based on adjusted or unadjusted estimates were not statistically significant, so the conclusion is that the prevalence of drug driving has not changed since Men were no more likely than women to have driven while impaired by drugs although this might simply be a reflection of under-reporting since drug use is more common among men. There were no clear age trends. Single people were more likely than people with a partner to have driven under the influence as were people who don t drive often. Those who had drug driven had higher sensation seeking scores than those who had not. The drug most commonly used was cannabis and most of the journeys undertaken while impaired were social. The explanations that respondents gave for drug driving were mainly centred on two key themes: positive incentives for drug driving and a lack of deterrents to dissuade. The main positive incentive for drug driving is the convenience of having their own transport and being able to make social journeys. There is a lack of disincentive to drug drive because most 4

6 people do not believe their driving is adversely affected. This view is common in both the survey and the depth interviews. Additionally, most drivers do not think there is a significant risk of being caught by the police. Both problem drug users and recreational drug users agree that there should be laws against drug driving and would welcome more reliable tests to identify drug drivers. The extent to which respondents displayed sensation seeking characteristics was measured with a standardised scale frequently used in psychological research on driving behaviour. Sensation seeking refers to individuals seeking novel or intense sensations and being willing to take risks to achieve these experiences. The survey showed that respondents who had reported involvement in the other types of risky driving behaviour had higher sensation seeking scores than those who had not. There was a relationship between drug driving and other types of risky driving. A higher proportion of drivers who had driven while impaired had also driven when they thought they were drunk, been flashed by a speed camera, had points on their licence or had been involved in an accident in the previous five years. Thirteen percent of the survey respondents said they had been a passenger in a car driven by someone under the influence of drugs. Almost half said they had been concerned about the individual s driving. Whether or not someone was concerned about the driving depended on their own past drug use and the types of drugs the driver had taken. From the interviews, most of the people who had been passengers had also been using drugs and were involved in social journeys. Those who had desisted from drug driving were more likely to be with a partner than those who had drug driven in the last 12 months, and to be aware of the implications and consequences of getting caught. Opinions on what would stop people drug driving were gathered and ideas that arose were advertising campaigns, more police on the roads and education in schools. Several implications can be drawn from the findings of this research. These include: targeting campaigns at single men, the group most likely to drug drive linking driving campaigns together, as all risky driving behaviours seem to be related to some extent making people more aware of the risks involved in drug driving, and having more police presence, more effective testing for drugs and more roadside testing for drugs. 5

7 CHAPTER 1: INTRODUCTION AND BACKGROUND Introduction The prevalence of driving under the influence of drugs has been causing increasing concern among those involved in the promotion of road safety and has been the focus of much recent research. In 1999, the Scottish Executive and the Scottish Road Safety Campaign (the SRSC changed its name to Road Safety Scotland in October 2005 and the new title will be used throughout the remainder of this report) commissioned the first Scottish study to examine the prevalence of, and attitudes towards, recreational drug use and driving among drivers aged years. Following the publication of this research, the RSS launched an advertising campaign aimed at reducing this figure, although this was subsequently found to have had limited impact. 1 In 2005, Road Safety Scotland and Scottish Executive commissioned a team comprising MORI Scotland, the Centre for Drugs Misuse Research at Glasgow University and Professor Steve Stradling of Napier University s Transport Research Institute to update and extend the 2000 study. In particular, this research aims to inform a more targeted campaign to reduce the prevalence of drug driving. Background There is a wealth of research outlining the prevalence of drug driving. Estimates depend on the methods of measurement used but most European studies report that around 4% of drivers aged 17 to 39 years have driven under the influence of drugs in the previous 12 months. 2 In line with this, the 2000 drugs and driving study reported that 9% of year old drivers had ever driven under the influence of drugs and 5% had done so in the previous 12 months. 3 The objective of the present study is to provide an up-to-date estimate of the prevalence of drug driving in Scotland which can be compared with the findings of the 2000 survey. A number of changes over the last five years might lead to an expectation that drug driving would be more prevalent in 2005 than in For example: there has been a general increase in drug use recorded between 1996 and 2003 in the Scottish Crime Survey 4 there is increasing car ownership and use among young adults the legal status of cannabis has changed and there is some evidence that cannabis use is more socially acceptable there have been increases in women s alcohol consumption and a narrowing of the gap between women and men in terms of other road traffic violations, 5 which may Ormston, R. (2003). Evaluation of the Drug driving TV Advert, Scottish Executive Social Research, Edinburgh Kelly et al., (2004). A review of drug use and driving: epidemiology, impairment, risk factors and risk perceptions Drug and Alcohol Review. Ingram, D., Lancaster, B. and Hope, S. (2000). Recreational Drugs and Driving - Prevalence Survey, Edinburgh: The Scottish Executive Central Research Unit McVie, S., Campbell, S. and Lebov, K. (2004). Scottish Crime Survey 2003, Scottish Executive Social Research, Edinburgh. Stradling et al., (2003). The speeding driver: Who, How and Why? Scottish Executive Social Research, Edinburgh 6

8 lead to the possibility that there will be some narrowing of the gap between women and men in terms of drug driving. Research Aims and Objectives The overarching aim of the research was to provide the Scottish Executive and Road Safety Scotland with a deeper understanding of the incidence of drug driving and the context in which it occurs. Key themes addressed in the research include: prevalence and trends of drug use in Scotland among drivers aged years prevalence and trends of drug driving in Scotland among drivers aged years key characteristics of drug drivers explanations of why people drive under the influence of drugs knowledge of, and attitudes towards, the law on drug driving the incidence of other risky driving behaviours and the links with drug driving the desistance from drug driving and views on past and possible future campaigns. The following chapter of the report details the methodology adopted for the research. Subsequent chapters present the main findings and the final chapter presents a broad overview of the findings with particular emphasis on any implications/recommendations for campaigns. 7

9 CHAPTER 2: METHODOLOGY The survey of year old drivers The approach adopted for the survey had, as a key objective, to provide a nationally representative sample of year old drivers to provide robust comparisons with the survey conducted in The broad approach was the same the absence of a sampling frame of drivers meant screening households to identify potentially eligible respondents and, within households, recruiting them to participate in the survey. The data for the survey, therefore, was intended to be representative of the general population of drivers aged years. Although the estimates can be compared with data from other studies such as the Scottish Crime Survey, or studies of drug use among sub-populations such as clubbers, people arrested for driving offences or people killed or injured in road traffic incidents, comparisons need to be mindful of the different bases on which the data are collected. The sample was selected using Census output areas (OAs) as primary sampling units. These have two advantages. First, they are small areas, averaging 50 households in Scotland and, therefore, represent an administratively efficient unit for an interviewer to be expected to screen all addresses in the area. Second, they are linked to Census data giving information on car ownership and the structure of the population. Although Census results are available for every output area, the Census does not allow us to identify year old drivers directly. It separately identifies the proportion of households with access to one or more cars and the proportion of the household population aged years. Either variable on its own is not an adequate basis for sampling since there is the possibility that an area with high car ownership would contain few year olds or that an area with a high proportion of year olds would have low car ownership. The sampling approach was as follows. 1. For every OA a proxy indicator of eligibility was calculated. This was the product of the proportion of car owning households and the proportion of the household population aged years. For example, an area with 70% car ownership and 25% of the population aged years would have a value of An area with the same proportion of year olds but only 30% car ownership would have a value of This indicator therefore gives higher probability of selection to areas with high car ownership and a high proportion of year olds. 2. The resulting indicator was multiplied by the total number of households in the OA to give an indication of the minimum number of eligible households in the area. Sample selection would also therefore take account of the potential size the eligible population. 3. Standard sampling assumptions based on the outcomes from the 2000 survey were used to convert the number of eligible households into a minimum interview yield. 4. Areas with an expected yield of less than 6 were combined with a neighbouring OA to ensure that an interviewer was able to work in each sampled area for three days to screen addresses and make repeated calls at addresses. 8

10 5. The remaining areas were sampled with probability proportionate to the number of potentially eligible households and every address within sampled OAs was screened to identify and interview eligible households. Fieldwork outcomes The survey achieved its target of just over 1,000 interviews although screening proved more difficult than expected. Compared with the 2000 survey, which reported an individual response of 76%, the response rate for the 2005 survey was 74% when calculated on the same basis. Table 1 Fieldwork outcomes comparable with 2000 survey Issued sample 9,860 Valid addresses 93% Valid sample 9,218 Screening response rate 89% Contacted sample 8,245 Proportion containing year old drivers 17% Eligible sample 1,398 Number of achieved interviews 1,031 Individual response rate 74% This suggests that the 2005 survey was, in fieldwork terms, as successful as the 2000 survey, achieving a high proportion of successful interviews in households that were successfully screened. Table 2 shows a more conventional calculation of the response rate, which shows the success rates for the survey at each stage of the household contact and screening process. Table 2 Survey response rate with allowance for unsuccessful screening. % of all Number addresses Totals 9,860 Property ineligible 642 7% Household ineligible because No one aged ,587 57% No drivers in household % Total ineligible 7,193 73% % of known eligible No contact with anyone in household % Contact but refused screening 296 3% Total unknown eligibility 1,269 14% Screened but respondent refused to participate 192 2% 14% Screened but no contact with selected respondent 176 2% 13% Successful interview 1,030 10% 77% Total known eligible 1, % 100% This gives a response rate of 77% of adults known to be eligible to participate but it highlights the fact that a number of households could not be screened and their eligibility is therefore not known. It is likely that some of these households would contain year old 9

11 drivers and that the true response rate is lower than 77%. If we assume that these households contained eligible respondents in the same proportion as was found in the other addresses that were screened (i.e. that 67% would be screened out because they did not contain any year olds or did not contain any drivers) the response rate would be 58%. Survey interviewing Although all the survey screening was undertaken by MORI interviewers, most of the data collection from respondents involved the person inputting their answers directly into handheld computers in a manner similar to a self-completion survey. The objective of this was to offer respondents as much anonymity as possible. Compared with normal face-to-face interviewing, the principal benefit of this type of self-completion interviewing for respondents is that questions do not need to be read out and answers given verbally. Respondents read the questions and answer them directly. Unlike paper questionnaires, routing is rigorously controlled and respondents answers disappear into the computer. However, respondents in this age group are unlikely to believe that their answers are truly hidden and so, in spite of reassurances, there remains the possibility that responses are affected by concerns about anonymity and confidentiality. This is discussed in subsequent chapters. Weighting There are two types of weighting normally used in surveys: weights to correct for aspects of the sample design and corrective weights to accommodate deficiencies in the achieved sample. In this survey the selection of one adult in households containing more than one eligible respondent needs to be accounted for by weighting. In terms of the sample design, this is the only weight required. After this weight was applied the sample was analysed both in terms of its geographical distribution and the age and sex structure of the sample. Geographical factors were important since it seems reasonable to expect differences in the prevalence of drug use and driving between individual local authorities, between urban and rural areas and between areas of relative deprivation and affluence. The analysis of geographical variables indicated that the sample required some correction between local authorities and in terms of the urban/rural balance of interviews. In essence, response was better in the more rural areas. Corrective weighting based on 2001 Census data and SHS data was used to remove this imbalance. In terms of the demographic profile of the sample, the principal concern was that there may be differences in the likelihood of young drivers to respond to the survey, mainly because they are less likely to be home when interviewers call. This type of non-response is potentially a significant source of bias. However, the age profile of year old drivers in this survey is not substantially different from the profile of drivers in the SHS and it was decided that no further weighting was required. 10

12 Table 3 Weighted and unweighted age profile of 2005 sample compared with 2003/2004 Scottish Household Survey and 2000 Drugs and Driving survey 2005 survey unweighted 2005 survey weighted SHS year old drivers 2000 survey weighted Follow-up interviews Qualitative depth interviews were a key part of meeting the study objectives relating to obtaining a more complete understanding of the motivations and circumstances of drug driving. Follow-up interviews were undertaken with four groups: survey respondents who said they had driven while impaired by drugs in the previous 12 months problem drug users who were involved with the Drug Outcome Research In Scotland (DORIS) project operated by the Centre for Drugs Misuse Research. survey respondents who had ever driven while impaired by drugs but not in the previous 12 months survey respondents who had ever been a passenger of someone driving while impaired by drugs but who had never done so themselves. Some problem drugs users who had been passengers of someone impaired by drugs were also interviewed. The survey respondents were all people who had agreed to take part in follow-up research as part of the questionnaire. Overall, 74% of survey respondents gave consent to be re-contacted and among the target sub-groups the corresponding rates were 78% for drivers who had ever driven while impaired by drugs, 81% for those who had driven while impaired in the previous year and 70% for passengers of impaired drivers. The interviews were conducted with respondents according to a topic guide agreed with the project advisory group. Interviews were recorded and transcribed before analysis. The number of potential respondents was limited by the number of each group identified in the survey. Also, respondents who had recently driven while impaired were prioritised over ever drivers so most difficulty was experienced with this group. At the end of the qualitative fieldwork the target number of interviews had been achieved in all but one group. DUI 12 months (year) 15 interviews completed DUI Ever 10 interviews completed compared with a target of 15 Problem drug users 30 interviews completed Passengers 20 interviews completed. 11

13 CHAPTER 3: PREVALENCE AND TRENDS IN DRUG USE Objectives The main objectives of this chapter are to: outline the prevalence of drug use in Scotland among drivers aged years compare these figures with previous surveys and identify any trends in drug use look at any changes in drug use among drivers across the past five years look at patterns of drug use, e.g. types of drug used, frequency of use Key findings Survey 39% of drivers had ever used drugs, 9% had done so in the last 12 months Reported drug use was lower than in other surveys, which may suggest that there was significant under-reporting of drug use in this survey. Analysis was undertaken of certain demographic variables: more men reported drug use than women there was no clear age trend with more year olds and year olds reporting drug use compared with the other age groups more people who were single reported recent drug use than those who lived with a partner The most commonly used drug was cannabis and this use was fairly frequent. Prevalence In collecting information about drug misuse, surveys tend to use the same basic approach. Respondents are presented with a list of drugs and asked if they have ever used any of those listed. Of those that have been used, respondents are asked if they have used each in the previous 12 months. In this survey, respondents were asked about 19 named drugs, one bogus substance Semeron used as an indicator of over-claiming and three general categories of drug: other tranquilisers, pills (unknown) and something to smoke (unknown). The full list was: Amphetamines Barbiturates Cocaine DF118s Diconal Heroin LSD Methadone Semeron Temazepam Other tranquilisers Something to smoke (unknown) Amyl nitrate Cannabis Crack Diazepam Ecstasy Ketamine Magic mushrooms PCP Solvents Temgesic Pills (unknown) 12

14 As shown in Figure 3.1, 39% of the sample reported ever having taken any of the drugs. This was higher than the figures reported in the 2000 survey (33%), and among adults in the same age group in the 2003 Scottish Crime Survey (34%). However, just under one in ten (9%) said they had taken drugs in the last year, a lower percentage than in 2000 and 2003 where 15% said they had taken drugs in the previous 12 months. Figure 3.1: Trends in drug use: ever and in the previous 12 months 40% 35% 30% 25% 20% 15% Ever Last 12 months 10% 5% 0% Base: Drivers years (1,008), Respondents years (1,593), Drivers years (1,031) Previously, gender has been found to be related to drug use, with more men reporting use of drugs than women. In this survey, almost half of all men said they had ever taken drugs (45%) compared with a third of women (33%) (shown in Figure 3.2). This is consistent with the 2003 Scottish Crime Survey (SCS), which found that 43% of men aged years and 31% of women had ever used any of the listed drugs. Similarly, a higher proportion of men than women had taken drugs in the past 12 months (12% of men compared with 7% of women). In comparison with the 2003 SCS, these proportions both appear to suffer from under-reporting. In 2003, 20% of year old men and 11% of year old women reported having used drugs in the previous 12 months. 13

15 Figure 3.2: Differences in drug use between men and women 50% 40% 30% 20% Ever Last 12 months 10% 0% All Male Female Base: Drivers years (1,031), Male drivers years (502), Female drivers years (529) The other variable that has been consistently found to be a key predictor of drug use is age. For example, in the 2000 drugs and driving survey, drug use in the last 12 months was found to be less common among older people and most common in the year old age group (31%). Figure 3.3 shows the results from Unlike 2000, recent drug use was found to be least common among year olds with 4% reporting use in the past twelve months. Recent drug use was most common in the and year old age groups. An important caveat, however, is that the sample sizes for both the 2000 and 2005 studies are not designed to provide estimates of change between the two surveys for the different age groups. The base size for the year old age groups is particularly low so this should not be taken as an indication that there has been a significant reduction in drug use in year olds. 14

16 Figure 3.3 Variation in drugs use by age 50% 40% 30% 20% Ever Last 12 months 10% 0% All Base: Drivers (1,031), year old drivers (62), year old drivers (177), year old drivers (209), year old drivers (271), year old drivers (312) Again, the reported drug use appears to be low among younger respondents than would have been expected in comparison with the 2003 Scottish Crime Survey, although again, we need to be clear that the intention is to show the difference between consistent patterns in ever drug use between the two surveys and divergent patterns of drug use in the past 12 months. Even though the drugs and driving survey is not designed to produce age-based estimates, we would have expected more similarity between the two surveys than these charts show, Figure 3.4 Differences in reported drug use 2003 Scottish Crime Survey and 2005 Drugs and Driving survey 50% 45% 40% D&D Ever SCS Ever 30% 25% D&D 12 months SCS 12 months 35% 30% 25% 20% 15% 20% 15% 10% 10% 5% 5% 0% All % All Another key characteristic that may be related to drug use is marital or living status. It is possible that when people settle down with a partner and take on increased responsibilities, they become less likely to use drugs. In support of this, Figure 3.5 shows that there is little difference in drug use ever between those who live with a partner (38% reported having ever used drugs) and those who live on their own (41%). However, more than one in ten (13%) respondents who live on their own reported drug use in the past twelve months compared with 7% of respondents with a partner. 15

17 Figure 3.5 Variation in drug use by marital/living status 45% 40% 35% 30% 25% 20% Ever Last 12 months 15% 10% 5% 0% All On own With partner Base: All drivers years (1,031), On own (484), With partner (547) Understanding changes in measured drug use For a number of reasons, household surveys have the potential to under-record illicit behaviours like drug use. First, it is possible that frequent drug users are less likely to be at home when interviewers call and, therefore, less likely to participate in the research. They might also be less willing to participate in research even if they are available. Secondly, there might be some stigma attached to drug use and, despite assurances of confidentiality, those who use drugs may not report use or choose to under-report it. Overall, the analysis of patterns and trends in drug use suggests that the 2005 survey may under-state the proportion of drivers aged years who had used drugs in the previous 12 months and there appears to be a particular problem of under-reporting among the two youngest groups of drivers year olds and year olds. The pattern of ever drug use is what would be expected. Since 2000, the surveys show a steady increase in the proportion of drivers (or year olds) reporting that they had ever used any drugs. The proportion rises from 33% of year old drivers in 2000 to 39% in However, the trend in 12 month drug use shows an unexpected drop in Whereas the 2000 drugs and driving survey and the 2003 Scottish Crime Survey record that 15% of year old drivers had used any drugs in the previous 12 months, the 2005 drugs and driving survey shows only 9%. The drop is dramatic in the age group 4% in this survey compared with 27% in the SCS and in the year old age group, which shows a drop from 28% in 2003 to 12% in There is some evidence of declining drug use among young people. For example, in the British Crime Survey the proportion of year old adults reporting having used any drug 16

18 in the previous 12 months fell from 27% in 2000 to 23.5% in 2004/ The decline in this survey is much greater. It seems unlikely that these changes reflect a real underlying change in patterns of drug use among young adults in Scotland. Nor do they reflect significant differences in survey method: the BCS, the SCS and the Drugs and Driving surveys used random sampling methods with self-completion data collection. This leaves us with two possibilities: That patterns of drug use among year old drivers, as measured by this survey, is different from that of the general population of year olds as measured by the Scottish Crime Survey. Young drivers may have experimented but are substantially less likely than their non-driving counterparts to be recent or regular users. This would give similar ever measures but divergent measures of drug use in the past 12 months. In the context of a survey on driving, young people are willing to report ever having used drugs but are reluctant to report recent drug use. The distinction between young drivers and young people in general could arise from the fact that only a small proportion of young people are drivers. In the 2003/2004 Scottish Household Survey, only 26% of year olds and 52% of year olds held a full licence. This rises steadily to 80% of year olds. The drugs and driving survey, therefore, is recording drug use among a relatively small sub-group of young people and drug use in this sub-group might be significantly different. However, there is also evidence of under-reporting. The 2000 drugs and driving survey recorded 29% of year olds having ever used any drugs and 20% having used drugs in the previous 12 months. The 2005 survey recorded 28% ever and only 4% in the previous 12 months in this age group. Similarly, 47% of year olds reported ever having used any drugs and 31% in the previous 12 months. The 2005 survey recorded 41% ever but only 12% in the previous 12 months. Since both drugs and driving surveys drew their samples from year old drivers, differences in survey coverage is unlikely to explain the differences in measures of drug use. These differences might arise either from: a significant but real change in behaviour, or a significant change in young people s willingness to report recent drug use. Such a significant behavioural change seems unlikely so it is concluded that there has been some change in the willingness of respondents aged under 25 years to report recent drug use. The small number of people in each of the sub-samples being compared also needs to be taken into account. The 2005 survey has 62 respondents aged years and the 2000 survey had 60. There is significant scope for random variation in the samples to produce large differences in the estimates. Understanding the extent to which drug use has been reported is obviously important for our understanding of the prevalence of drug use and driving. Having concluded that there appears to be under-reporting, the estimation of the amount of under-reporting was as follows: 6 Roe, S. (2005). Drug misuse declared: findings from the 2004/05 British Crime Survey (England and Wales) Home Office Statistical Bulletin 16/05, London. 17

19 1. Across the three previous surveys (2000, 2003 SCS and 2004 SCVS 7 ), there is a fairly stable relationship between the proportion of year old drivers (2000 survey) or year olds in the general population who had ever used drugs and the proportion who had used drugs in the previous 12 months. Across the three surveys, the proportion of respondents who had ever used drugs who also reported using drugs in the previous 12 months was 41%. 2. It assumes that, were it not for under-reporting, the same relationship would exist in 2005 and that about 41% of respondents who had ever used drugs would also have used drugs in the past 12 months. 3. Since 39% of year drivers reported ever having used drugs in 2005, if 41% of them had also used drugs in the previous 12 months, this would suggest that the figures for drug use the past 12 months should be around 16% - almost double the 9% actually recorded in the survey. Estimating the extent to which drug use might have been under-reported in relation to previous surveys is important for two reasons. First, it says something about the social acceptability of reporting drug use. The implication of the findings is that, compared with 2000, it has become less acceptable for drivers aged years to report recent drug use. Second, the under-reporting will have a knock-on effect on the estimate of drug driving, since the structure of the questionnaire means that only people who have reported using drugs in the previous 12 months were asked if they had driven shortly after taking drugs. The implications of under-reporting drug use are discussed below. Although an attempt has been made to estimate the amount of under-reporting, no adjustment of the survey data has been made to try to account for under-reporting, particularly in terms of respondent characteristics or behaviours. First, it is not certain that the survey is underreporting although it appears likely to be. Second, while it is possible to estimate at an aggregate level, the accounting would need to be done for small sub-groups for it to make any difference to the survey results. It would be unreliable to calculate and apply weighting factors to the very small groups involved in this survey. Types of drugs used The overall estimates of drug use do not give information on the types of drugs that have been used in these periods. Due to the small number of respondents who reported drug use, it is necessary to look at different categories of drugs rather than individual drugs. For the purpose of this analysis, the drugs have been grouped into five main categories. This is similar to approaches that have been used in previous surveys and identical to the approach adopted by the 2000 drugs and driving survey to enable comparison across the surveys. 7 In 2004 MORI and TNS Social undertook a repeat of the 2003 Scottish Crime Survey as part of a study to estimate the impact of switching crime survey data collection to telephone interviewing. This involved collecting data on drug use from a random sample of Scottish adults. The data are not yet published and cannot be reported here but the estimates from the survey have been used as part of this exercise with the agreement of the SCVS project manager. 18

20 Table 3.1: Categorisation of drugs for analysis Cannabis/ smoke (unknown) CNS stimulants/ hallucinogens Opiates CNS depressants Other drugs Cannabis Amphetamines Cocaine Barbiturates Solvents Smoke (unknown) Amyl nitrate Crack DF118 Pills (unknown) Ecstasy Diconal Diazepam GHB Heroin Temazepan Ketamine Methadone Other tranquillisers LSD Temgesic Magic Mushrooms PCP The most commonly used category of drug was cannabis/smoke (unknown) with more than a third of respondents (35%) having tried these at some point in their lives. One in five (21%) had ever used drugs in the stimulants/hallucinogens category such as ecstasy and magic mushrooms. An increased proportion of respondents reported having ever used opiates in the 2005 survey compared with the 2000 drugs and driving survey (10% compared with 5%). No respondents reported use of Semeron, the bogus drug that was included to measure overclaiming. The pattern of drug use is similar for the previous twelve months, as cannabis is also the most commonly used drug (7%). Similar proportions of respondents reported having used drugs in the stimulants/hallucinogens, opiates and suppressants categories. Table 3.2 Categories of drugs taken ever/ past twelve months Drug Ever Past twelve months % % Any drug 39 9 Cannabis/smoke (unknown) 35 7 Stimulants/hallucinogens 21 3 Opiates 10 3 Suppressants 8 3 Other drugs - * Base: All drivers years (1,031) Respondents were also asked how often they took drugs. The numbers for each category are too small to report so only the numbers for cannabis are reported. Forty-three percent of those who reported using cannabis in the previous twelve months said they had done so once a month or more often. The most substantial change between 2000 and 2005 is the significant increase in the proportion of drug users who said either they didn t know or couldn t remember how often they took cannabis. In 2005, the proportion of don t know/can t remember responses is five time higher than in 2000 (15% compared with 3%). Similarly, twice as many respondents refused to answer the question than in This fits with the suggestion that there is more of a stigma attached to drug use than in 2000 that is resulting in under-reporting or refusal to report accurately. 19

21 Table 3.3 Frequency of use of cannabis Frequency of use All past twelve month cannabis users 2005 All past twelve month cannabis users 2000 % % Once a week or more often Two or three times a month 8 10 Once a month or more often 13 9 Once every three months Once or twice a year Don t know/can t remember 15 3 No response 6 3 Base: (All drivers who reported use of cannabis users)

22 CHAPTER 4: THE PREVALENCE OF DRUG DRIVING Objectives The objectives of this chapter are to: outline the prevalence of drug driving in year old drivers identify the characteristics of those who have driven under the influence of drugs identify any link between drug driving and sensation seeking, a personality characteristic frequently found to be related to risky behaviours explore the circumstances of drug driving Key findings Survey 6% had ever drug driven. 3.5% had done so in the last 12 months. Although lower, these figures were not significantly different from those in the 2000 drugs and driving survey and may be a result of under-reporting of drug use Analysis of demographic variables showed: men were no more likely than women to report drug driving there were no clear age trends single people were more likely to have drug driven in the past year than those who live with a partner more people who do not drive often, reported drug driving than those who drive every day or every week drug drivers have higher sensation seeking scores than other drivers The drug most commonly used before driving under the influence was cannabis. Most journeys were for social reasons Depth interviews The recreational drug users mostly drove while under the influence for social and personal reasons The problem drug users said that they were almost always under the influence of drugs. Thus every time they drove, they were under the influence. Prevalence of drug driving Respondents who had ever used any drugs were asked if they had ever driven a vehicle within a defined period of taking each drug they reported having taken. For example, a respondent who reported having used cannabis was asked if they had ever driven within 12 hours of taking cannabis. The period varied depending on the drug. The shortest period was 30 minutes for Amyl Nitrate to 24 hours for Heroin. Times were chosen to reflect, as closely as possible, the time within which each substance was likely to have an impairment effect. 21

23 Across the sample as a whole, 6% of respondents said they had ever driven under the influence of any drug and 3.5% had done so in the last 12 months. As a proportion of those who had ever taken drugs, 16% had ever driven under the influence of drugs. In 2000, 10% of respondents said they had ever driven under the influence of drugs and 5% of respondents said they had done so in the last 12 months. As shown in Figure 4.1, this represents a decrease in the prevalence of drug driving. It is important to note, however, that this decrease is not statistically significant, i.e. it is not large enough for us to say that it is not caused by the type of random variation that might be expected in a sample survey like this. Figure 4.1: Drug driving ever/past twelve months 10% 9% 8% 7% 6% 5% 4% Ever Last 12 months 3% 2% 1% 0% Base: All drivers years (1,008), All drivers years (1,031) However, having concluded in the previous chapter that recent drug use was likely to have been under-reported, we need to consider the implication of this for our estimate of drug driving, since the two are directly related in the survey design. 8 The only reasonable assumption that can be made about the impact of under-reporting is that the relationship between ever drug use and drug driving is as stable as the relationship between ever drug use and recent drug use. If this were the case it would suggest that, rather than 16% of recent drug users having driven while impaired, the figure should be closer to the 29% recorded in This results in an estimate of 11% ever having driven under the influence of drugs, with 6% having done so in the previous twelve months. While this suggests a slight increase in drug driving since 2000, this is not statistically significant, i.e. it is likely to be attributable to sampling variation rather than any real change. The important conclusion to draw from this is that drug driving among year old drivers appears to be no more or less prevalent than it was five years ago. This is true whether we 8 Respondents were only asked about driving after using drugs if they had reported using drugs. Any under-reporting of drug use would therefore have a direct impact on the measure of drug driving. 22

24 take the figures directly as they were reported by respondents or make adjustments to account for under-reporting. The other important conclusion to draw from this is that the most likely explanation for under-reporting is that there is more stigma attached to drug use than there was in 2000, which makes people less likely to report their behaviour. This might be context sensitive, i.e. in the context of a survey about driving. It suggests that, although evaluation research questioned the effectiveness of the drug driving campaign, 9 this and more general campaigns directed at drug use, notably the Know the Score campaign, 10 may have impacted on perceptions of impaired driving at least to an extent that makes people less likely to want to admit to it (in spite of assurances of confidentiality). While the prevalence of drug driving has not decreased since 2000, this under-reporting might indicate increased stigma around drug use in general, and with driving while impaired by drugs. Characteristics of drug drivers In order to successfully target campaigns, it is crucial to identify which groups are most likely to drive while impaired by drugs. As noted in Chapter 3, drug use was associated with gender, age and marital/living status. As Figure 4.3 shows, 8% of men said they had ever driven while impaired by drugs and 4% said they had done so in the previous 12 months. The proportions of women who said they had drug driven was 5% for the ever measure and 2% in the previous 12 months. Although women appear to be less likely to drive while drug impaired, the difference is not statistically significant. Also, when compared with the 2000 survey, it is clear that the proportion of women who had driven while impaired by drugs has not increased over the previous five years, despite the recent upwards trends in drug use and driving patterns among women Ormston, R (2003) Evaluation of the Drug driving TV Advert, Scottish Executive Social Research, Edinburgh

25 Figure 4.3 Differences in drug driving between men and women 8% 7% 6% 5% 4% 3% Ever Last 12 months 2% 1% 0% All Male Female Base: Drivers years (1,031), Male drivers years (502), Female drivers years (529) Drug driving is also associated with age. Previous research has suggested that younger drivers may be more likely than older drivers to drive while impaired by drugs. In 2000, more drivers in the year old age group (13%) had taken drugs and driven in the past 12 months. This figure decreased across the age groups with only 1% of year olds drug driving in the previous 12 months. In the 2005 survey, the age demographic does not follow such a clear pattern, as displayed in Figure 4.4 below. Consistent with the findings for drug use, those most likely to have drug driven in the last 12 months were in the year or year age bands. A very small number of year olds reported drug driving. 24

26 Figure 4.4 Differences in drug driving by age group 9% 8% 7% 6% 5% 4% Ever Last 12 months 3% 2% 1% 0% All Base: Drivers (1,031), year old drivers (62), year old drivers (177), year old drivers (209), year old drivers (271), year old drivers (312) Figure 4.5 shows variation in drug driving by living/marital status. Similar proportions of respondents who lived on their own (i.e. not with a partner) and those who lived with a partner said they had ever driven while impaired. However, more respondents who lived on their own reported having drug driven in the previous 12 months (6% of respondents who lived on their own compared with 1% of respondents who lived with a partner). 4.5 Variation in drug driving by Marital/living status 7% 6% 5% 4% 3% Ever Last 12 months 2% 1% 0% All On own With partner Base: All drivers years (1,031), On own (484), With partner (547) 25

27 Drug driving was also examined by frequency of driving and this is shown in Figure 4.6. For both the ever measure and the previous 12 months, those who reported that they did not drive often were more likely to have driven under the influence of drugs. Figure 4.6 Variation in drug driving by frequency of driving Ever Last 12 months All Every day Weekly Not often Base: All drivers (1,031), Drivers who drive every day (828), Drivers who drive weekly (160), Drivers who do not drive often (43) Drug driving and sensation seeking Respondents also completed a sensation seeking scale. The concept of sensation seeking was developed by Zuckerman and is defined as the need for varied, novel, and complex sensations and experiences, and the willingness to take physical and social risks for the sake of such experiences. 11 The scale used in the survey was devised by Arnett and has been used in previous studies of driving behaviour. 12 Across the 20 items in the scale, respondents could score between 20 and 80 depending on the extent to which they thought each sensation seeking item applied to them. A higher score indicates a higher propensity for sensation seeking. Figure 4.7 shows the mean sensation seeking scores for drivers who had ever taken any drugs but not driven while impaired, those who had ever driven while impaired but not in the previous 12 months, and those who had driven while impaired in the previous 12 months. Recent drug drivers had the highest sensation seeking scores while those who had drug driven ever had higher scores than those who had used drugs but not driven while impaired. Nondrug using drivers had the lowest scores. Significance testing found that the two drug driving groups did not differ between themselves on sensation seeking but scored significantly higher than those who had used drugs ever and the rest of the population. Those who had used drugs in the last 12 months had significantly higher scores than those who had used drugs ever Zuckerman, M (1979) Sensation seeking: Beyond the optimum level of arousal. Hillsdale: Lawrence Erlbaum Associates Arnett, J. (1994) Sensation seeking: A new conceptualisation and a new scale. Personality and Individual Differences 26

28 Figure 4.7 Mean sensation seeking scores drug driven in last 12 months drug driven ever drug use in last 12 months drug use ever rest of population The implication of this is that the sensation seeking scale distinguishes people with personality characteristics associated with drug driving. This is discussed further in subsequent chapters. Circumstances of drug driving Respondents in the 2005 survey who had driven while impaired by drugs were asked to think about the last time they had driven a vehicle after taking drugs. Table 4.1 shows which drugs they had taken. The most commonly reported drug was cannabis. However, over one in ten had driven under the influence of stimulants (13%), opiates (12%) or suppressants (15%). Six percent said they had also had something alcoholic to drink in addition to the drugs but 10% said they could not remember. This suggests that the 6% may be an under-estimate of whether alcohol was also involved. Table 4.1 Categories of drugs ever driven under the influence of/driven under the influence of in the last twelve months Drug Last time drug driven % Cannabis/smoke (unknown) 56 Stimulants/hallucinogens 13 Opiates 12 Suppressants 15 Other drugs 3 Base: All drug drivers (36) These respondents were also asked where they were going to/from the last time they had drug driven. Many were going to or from a friend s or relative s house (49%). Almost one in five 27