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Chapter 3: Estimating the Prevalence of VSA

Introduction

Due to the hidden nature of VSA, it is a difficult task to provide an accurate estimate of VSA prevalence. This is reflected in the lack of available data that report on the prevalence of VSA, both in Scotland, and at the wider level.

Most of the evidence that is available comes from prevalence surveys, including household surveys and mainstream schools based surveys and from reported cases of individuals attending drug treatment centres. Both methods rely on self-reported drug use.

Prevalence Surveys and Statistics

In the last 15 years, there has been an emergence of school and household based surveys that explore experience of a number of illegal drugs, cigarettes and alcohol and solvents. For the most part, questions focus on;

• lifetime use: whether respondents have ever taken the drug
• recent use: whether they had taken the drug in the last year
• current use: whether they had taken the drug in the last month.

This section provides an overview of the main surveys and their findings from recent survey sweeps.

UK and Ireland

The majority of survey data relating to drug use in Scotland has focussed on young people and has been collected using in-school surveys. Less data exists for drug use in general, and specifically VSA, among adults.

The Scottish Schools Adolescent Lifestyle and Substance Use Survey ( SALSUS) survey, previously undertaken by the Edinburgh University Child and Adolescent Health Research Unit ( CAHRU), is in its third sweep, with previous surveys having been carried out in 2002 and 2004. The survey, which is commissioned by the Scottish Executive, collects data from secondary school students aged 13 and 15 on smoking, drinking and drug use. Substance use is considered in the wider context of other lifestyle, health and social factors. It was preceded by a number of UK wide surveys carried out by the Office for National Statistics ( ONS), 1982-1998, and National Centre for Social Research ( NCSR) and the National Foundation for Educational Research in 2000.

Table 1 shows that, in 2004, 2% of 13 year olds and 4% of 15 year olds reported use of gas, glue or other solvents in the last year (compared to 10% and 28% for cannabis, and 3% and 10% for stimulants including cocaine, ecstasy and amphetamines). This reduced to 1% in both age groups for use in the last month (compared to 6% and 19% for cannabis and 2% and 4% for stimulants including cocaine, ecstasy and amphetamines).

Table 1

Analysis of survey results from the previous sweeps (Table 2) shows that, for older students, there was a decrease in having been offered gas, glue and other solvents, from 24% in 2000 to 14% in 2002 and 13% in 2004. This compares favourably to other drugs. For example, in 2000, 28% of students reported having been offered cannabis, compared to 26% in 2002 and 26% in 2004. In 2000, 16% of respondents said that they had been offered stimulants compared to 11% in 2002 and 11% again in 2004.

Table 2

Equivalent data for England and Wales from the 2004 Smoking, Drinking and Drug Use ( SDD) Survey showed that, 6% of 13 year olds and 6% of 15 year olds reported use of glue, gas, aerosols or solvents in the last year (compared to 7% and 26% for cannabis, and 4% and 12% for stimulants including cocaine, crack, ecstasy, amphetamines and poppers). These figures are notably higher than those reported for Scotland, especially the figure for solvent use among the younger age group.

In 2003, a Justice Department buy in to the MORI Scotland omnibus survey - State of the Nation - provided data regarding use of solvents and other drugs among children and young adults. Face-to-face interviews with 972 17-25 year olds, who also completed self-completion surveys, revealed that 11% of respondents had, at some time in their lives, tried glues, gas or aerosols to sniff or inhale. Further, 2% said that they had been offered these substances in the previous 12 months and 1% said that they had been offered them in the previous month.

The National Crime Surveys of England and Wales, and Scotland, have also collected data relating to drug use and awareness.

In Scotland, there have been 4 crime surveys, in 1993, 1996, 2000 and 2003, each of which has collected data on drug use. Findings from the 2003 Scottish Crime (and Victimisation) Survey showed that, of all adults who responded (n=3,168), 2.7% said that they had ever used glues, gases or other solvents (an increase compared to 1.4% in 2000 and 2.1% in 1996). Less than 1% (0.1%) said that they had used solvents in the previous month (similar to 0% and 0.2% reported in 2000 and 1996 respectively).

A closer analysis of the profiles of those who said that they had used glues, gases or other solvents at least once before showed that prevalence was greater among those aged under 30 than over 30, with no notable differences between male and female use (2.9% and 2.6% respectively). Analysis of solvent use by gender and age shows that self-reported use 'ever' decreased with age for female respondents, (ranging from 7.1% for females aged 16-19 to 1.3% for females aged 40-59) whilst, for males, there appeared to be peaks in self-reported solvent use 'ever' for those in age bands 16-19 (4.7%), 25-29 (5.8%) and 35-39 (5.4%). The finding for females is consistent with earlier surveys and the 2000 survey also showed a peak for males aged 25-29 of 7.5% usage 'ever'.

Data for England and Wales regarding use of glues among adults aged 16-59 is also available from the British Crime Survey. The latest survey report regarding substance misuse for this age group (Chivite-Matthews et al., 2005) shows a decrease in the use of glue between 1998 and 2004. The recorded prevalence of glue use in the last month and last year reported by this survey is less than 1% in both cases, with reported lifetime use among 2% of respondents. Among 16-24 year olds, prevalence of lifetime use was noted among 3% of respondents.

Northern Ireland

Drug use in general has been recognised as a growing issue in Northern Ireland and, as a result, there has been much research activity in the previous 10 years. A comprehensive overview of drug research in Northern Ireland can be found in the Register of Drug and Alcohol Related Research in Northern Ireland ( DAIRU, 2004).

The European School Project on Alcohol and other Drugs ( ESPAD) surveys in 1995 and 1999 showed that Northern Ireland had the highest rate of reported inhalant abuse of all participating European countries. In 1995, 26% of 15 and 16 year olds who took part in the survey reported ever having used inhalants, whilst 25% of respondents in 1999 reported lifetime use. In 1999, this figure was 11% higher than the rate for England, 8% higher than for Scotland and 6% higher than Wales. The rate for the Republic of Ireland was 22% (Higgins, Percey and McCrystal, 2004).

That said, however, the 2000 and 2003 modules on drug use taken from the Young Persons Behaviour and Attitudes Survey in Northern Ireland show that the proportion of pupils saying that they had ever used solvents fell from 16% in 2000 to 10% in 2003.

Further, findings from the 2002/03 Drug Prevalence Survey which provides a breakdown of drug use for Health Boards in Ireland, and Health and Social Services Boards for Northern Ireland, showed a lifetime prevalence of solvent use of less than 5% in all regions for people aged 15-64.

Despite this, there continues to be a high standard mortality ratio for VSA associated deaths in Northern Ireland. The standard mortality ratio for all ages, for the period 1995-2004, was 136 deaths in Northern Ireland - the third highest after the North East of England (158) and the East Midlands (137), (St George's, University of London, 2006).

European

The European School Project on Alcohol and other Drugs ( ESPAD) provides standardised prevalence estimates of rates of alcohol, tobacco and other drug use among school children for participating countries across Europe, including the UK. Previous sweeps have been carried out in 1995, 1999 and 2003.

Data from the 2003 summary report (involving 35 countries) showed that the highest prevalence rates of lifetime inhalant use among young people in Europe were recorded for Greenland (22%), Cyprus, Greece, Ireland, Isle of Man, Malta and Slovenia (all with rates between 15-19%). The prevalence rate for the UK was 12%.

A more detailed analysis of findings from the 2003 ESPAD survey, specifically in relation to VSA, is due to be published later this year (Ives, in press).

America

In the US, data relating to inhalant abuse is collected via 3 principal surveys of the nation's youth.

The University of Michigan's Monitoring the Future study surveys around 50,000 American secondary school students and young adults on an annual basis regarding behaviours, attitudes, and values. The nationwide survey has been running since 1975 and provides data relating to the prevalence and frequency of drug use among American secondary school students and historical trends in use.

The 2005 survey report, covering the period 1975-2004, shows an increase in the US of inhalant use among secondary school students in the early 1990s, which reversed after 1995.

Despite this, in 2004, among 12 year old students, inhalants emerged as the second most frequently used drug in terms of prevalence of use in the previous year (marijuana being the most prevalent). For this age group, one in 6 (17%) reported that they had at one time used inhalants, and 1 in 24 (4.5%) said that they had used them in the past month. In the 2004 survey, inhalants were the drugs on the questionnaire index for which use was substantially higher among younger students compared to older students.

Importantly, when asked about drugs ever used, inhalants ranked first on lifetime use. The authors report that this finding may be skewed by high levels of reporting among younger participants. That is, in 2004 the proportion of 8th grade students reporting any illicit drug use in their lifetime, exclusive of inhalants, was 22%, compared to 30% when inhalants were included. In comparison, inclusion of inhalants on the index of drugs used makes relatively little difference to the prevalence rates of older students. The authors speculate that that this may be as a result of reluctance of older students to report ever having used inhalants since they may be considered as immature.

The report also notes that one specific class of inhalants, namely amyl and butyl nitrites, has shown a significant decrease in popularity falling from a peak prevalence rate among 12th grade students in the late 1970s of 6.5% compared to only 0.8% of survey respondents in 2004.

Also in the US, the National Survey on Drug Use and Health
(formerly called the National Household Survey on Drug Abuse ( NHSDA)), has collected data relating to inhalant abuse since 1985. Conducted by the Substance Abuse and Mental Health Services Administration, the survey is an annual survey of the civilian, non-institutionalised population of the United States aged 12 years old or older.

The most recent survey results show that, in 2004, approximately 857,000 persons had used inhalants for the first time in the previous 12 months. This number was relatively static compared to figures from 2002 and 2003. The majority of those reporting first time use (75%), were aged under 18 at the time that they first used inhalants. In 2002 and 2003, an annual average of 718,000 (8.6%) of young people aged 12 or 13 reported that they had used inhalants at least once in their lifetime.

A detailed analysis of inhalant abuse for different sectors of the US population is provided in a series of tables that can be found at http://oas.samhsa.gov/

Finally, data from the 2003 National Youth Risk Behavior Surveillance System ( YRBSS) supports the finding that inhalant abuse is more prevalent among early teens compared to older teenage students. The survey, which monitors six categories of priority health-risk behaviors among youth and young adults, including alcohol and other drug use, showed that, nationwide, 3.9% of students had used inhalants one or more times during the 30 days preceding the survey administration (ranging from 2.4% to 5.5% in different States).

The prevalence of current inhalant use was higher among 10th grade male (4.3%) and 11th grade male (4.1%) than 10th grade female (2.6%) and 11th grade female (2.0%) students, respectively. The authors note a general trend for male use to be higher than female use as well as greater reporting of abuse by younger students compared to older students.

Survey Limitations

Although, generally, survey data provides indicative prevalence information, and has become the standard means by which drug misuse information is collected both in the UK and elsewhere, this method of estimating prevalence is not without problems.

For school surveys, there may be a degree of under-reporting of VSA, especially given the perceived lack of credibility of reporting solvent abuse among older children, compared to younger peers. Some survey authors have argued that this has been evidenced by lifetime prevalence of older children being lower than lifetime prevalence of younger respondents. The lack of longitudinal tracking based surveys makes this difficult to show conclusively.

Some authors have also commented that the school based approach is inherently flawed since those who engage in VSA are, arguably, amongst those most likely to be absent from school at the time that such surveys are undertaken, through truancy or other health or social reasons. In Romania, for example, research has shown that VSA is high among street children. This limitation is compounded by a lack of comparable surveys in residential and secure schools.

Also, there is considerable variation in the sampling criteria, sample size and classifications of drug misuse across different surveys which makes comparison between jurisdictions difficult. This is especially true in relation to age of respondents, with much variation in the age groups targeted. Surveys such as ESPAD do provide some solution to this problem.

At the general level, the response to VSA questionnaires is known to be very sensitive to the wording of questions used, and the confidence intervals for social research data can be quite wide.

Finally, the SALSUS survey in Scotland, which perhaps provides the core data in relation to VSA prevalence among young people in Scotland has, for the 2006 sweep, experienced a change in the time period at which data is collected. This may impact on any future reporting of trends in VSA between previous and subsequent sweeps of the survey.

Other Scottish Data

As part of the review, a number of local authorities were contacted to explore if information was held locally about VSA across Scotland. In most cases, the only data available is that reported to the ISD Scottish Drug Misuse Database ( SDMD). This national database provides drug use prevalence information based on recorded attendance by problem drug users at treatment services across Scotland.

The Scottish Drug Misuse Statistics 2005 publication (which reports on National Statistics data from the SDMD, General Acute Hospital Inpatient Statistics and Prescriptions Relating to Drug Misuse, for the year ending 31 ^st March 2005) shows that:

• 78 people (<1%) who attended services and reported illicit drug or alcohol use had (at some time in the previous year) used solvents
• the local authorities reporting the highest numbers of solvent users attending drug services were Fife (n=23, 29%), Edinburgh City (n=9, 12%) and North Lanarkshire (n=8, 10%)
• the health boards reporting the highest number of solvent users attending drug services were Fife (n=23, 29%), Lothian (n=11, 14%) and Greater Glasgow (n=10, 13%)
• of all those who provided information about main illicit drug use (=2868), solvents accounted for just over 1% (n=32)
• Fife NHS Board and Fife Local Authority recorded the highest number of service users form whom solvents were the main illicit drug (n=7, 22%).

In relation to general acute inpatient discharges with a diagnosis of drug misuse, the report shows that:

• six people were diagnosed as using volatile solvents (<1%)
• two of these were aged under 16, 3 were aged 30-40 and one was aged 20-24 years
• five were male and one was female.

Of all those admitted, and diagnosed as using volatile solvents, all were discharged within one week.

The report also shows that the number of inpatient discharges for VSA in 2004/05 (n=6) was at its lowest in the last 5 year period with previous numbers being 15, 26, 20 and 25 for 2000/01.

It is worth noting, again, that the numbers reported here are low and any generalisation of these findings, based on such small sample sizes, should be made with caution.

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