1. Background and definition

New psychoactive substances (NPS) started to become more popular on the UK drugs scene around 2008 to 2009, with synthetic stimulants such as benzylpiperazine (BZP) and mephedrone, and synthetic cannabinoids (such as "Spice"), among the first to gain popularity. NPS are sometimes referred to as legal highs, but many are now controlled under the Misuse of Drugs Act 1971, so are no longer legal.

This article focuses on substances that were not controlled under the Misuse of Drugs Act 1971 on the day the person died, and are referred to as legal highs throughout this article. It covers a 10-year time period from 2004 to 2013. Various drugs on our list have been controlled during this period, consequently, the drugs included in our definition of a legal high change throughout the analysis period, as drugs are removed from the list once they become illegal. For example, mephedrone was banned on 16 April 2010, so deaths involving mephedrone are only included if they occurred between 1 January 2004 and 15 April 2010.

We publish an annual statistical bulletin on Deaths related to drug poisoning in England and Wales, which contains statistics on deaths involving a wide range of substances. Figures on NPS deaths in that bulletin are based on a much broader definition and include drugs that are now controlled under the Misuse of Drugs Act 1971.

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3. Blanket ban on psychoactive substances

The government has already banned a large number of NPS under the Misuse of Drugs Act 1971. However, it has been difficult to control the use of NPS with existing legislation, as when one drug (or group of drugs) is controlled, scientists simply tweak the chemical structure of the drug so that it evades the law. The government, therefore, remains concerned about how quickly NPS are being created and the potential harm they pose. To address this problem they have introduced the Psychoactive Substances Act, which will come into force in spring 2016. This establishes a blanket ban on the importation, production or supply of psychoactive substances, though things like alcohol, tobacco, caffeine and medicines used in healthcare-related activities will be exempt.

Evidence on the harms of a range of NPS are documented in reports by the Advisory Council on the Misuse of Drugs (ACMD), but how many deaths do they actually cause?

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9. Impact of banning mephedrone

The previous sections looked at deaths where the substances involved were legal at the time of death. This section contains a case study of mephedrone – one of the first legal highs to catch the media’s attention – and looks at trends in deaths before and after it was banned. Mephedrone, sometimes called "Meow meow" or "M-Cat" is a cathinone which was controlled as a Class B substance under the Misuse of Drugs Act 1971 on 16 April 2010, along with a number of other cathinones.

Deaths involving mephedrone did not immediately fall after it was banned

The first death involving mephedrone occurred in 2009, and deaths continued to rise for several years following the ban, peaking at 22 deaths in 2012, before falling to 12 deaths in 2013. This suggests that banning mephedrone did not immediately reduce the number of mephedrone-related deaths. However, it is possible that mephedrone use would have increased and deaths would have been even higher, had it not been banned.

Mephedrone was first included in the Crime Survey for England and Wales – CSEW – (Home Office, 2015a) in 2010/11, when 1.3% of 16 to 59-year-olds reported using mephedrone in the last year, although the figure was higher for young people – 4.4% of 16 to 24-year-olds. Use had dropped to 0.6% of 16 to 59-year-olds in the 2013/14 CSEW (around 211,000 people) and to 1.9% of 16 to 24-year-olds.

The trend in use of mephedrone is not consistent with the number of deaths, which peaked in 2012, but by then the proportion of people using mephedrone had more than halved. At first glance, this pattern might suggest that people were less willing to admit to taking mephedrone since it was banned. However, the majority of people who reported using mephedrone in the Crime Survey, also reported using another illegal drug, so it’s not clear whether banning mephedrone would suddenly lead to under-reporting of its use.

There is unlikely to be a simple explanation of why deaths involving mephedrone continued to increase while use apparently declined. It may be that the drugs that people are now taking with mephedrone are more dangerous; or they are using riskier methods to take mephedrone (for example, injecting instead of snorting); it could be that people are experiencing increasing harm having used mephedrone for a longer period of time, with escalating doses leading to more fatal overdoses; or it is possible that a more vulnerable group of people have begun using mephedrone. In addition, it is possible that people stockpiled mephedrone before it was banned, which may have affected patterns of use after the ban. Any of these factors could have lead to the increases in deaths involving mephedrone seen between 2009 and 2012. The fact that deaths involving legal highs in general continued to rise in 2013, while deaths involving mephedrone fell, may suggest mephedrone is becoming less popular and people are now taking different types of NPS.

These data suggest there is a complex relationship between a drug’s legal status, how widely it is used in the population and the number of deaths that occur. And it will be interesting to see what impact the introduction of the Psychoactive Substances Act 2016 will have on the longer term trends in deaths involving NPS.

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11. Methodological considerations

Registration delays

Due to the length of time it takes to complete a coroner’s inquest there can be a considerable delay between when a death occurred and when it was registered (5 to 6 months on average for drug-related deaths). All data presented above are based on the date the death occurred, not when it was registered. Due to registration delays, many of the deaths that occurred in 2014 and some of those that occurred in 2013 will not have been registered when this data extract was taken (that is, by 31 December 2014). Therefore figures for 2014 are not presented as they are too incomplete and figures for 2013 should also be treated with caution, as they are likely to be an underestimate of the total number of legal high deaths occurring in that year.

Data on drug-related deaths registered in 2015 are currently being processed and figures will be published on our website in September 2016.

Other limitations of ONS drug-related deaths data

The figures on deaths involving legal highs reported in this article are likely to be an underestimate of the true numbers and need to be interpreted with caution for the following reasons:

  • the number of deaths is very small, making it harder to interpret changes from one year to the next
  • these figures are based only on information reported on the coroner’s death certificate so may not include every substance involved in the death
  • there may not be toxicology tests available to detect the newest psychoactive substances, and coroners may not be able to afford to test for every new substance: this is especially the case in deaths where a more common substance such as heroin or cocaine has already been found at post-mortem
  • alternatively, the increases in legal high deaths in recent years may be due to coroners becoming more aware of these substances and so they are more likely to be tested for at post-mortem
  • in around 1 in 10 drug poisoning deaths, only a general description is recorded on the coroner’s death certificate (such as drug overdose or multiple drug toxicity)
  • in around 30% of all drug poisoning deaths, the death certificate mentions more than one specific drug; where more than one drug is mentioned, it is not possible to tell which was primarily responsible
  • approximately 30% of all drug-related poisoning deaths also contain a mention of alcohol or a consequence of long-term alcohol abuse (for example, cirrhosis) in addition to a drug
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12. References

  1. Advisory Council on the Misuse of Drugs – ACMD (2011) ‘Consideration of the Novel Psychoactive Substances (‘Legal Highs’)’, accessed on 21 April 2016.

  2. Advisory Council on the Misuse of Drugs – ACMD (2016) Risk assessments of a range of NPS, accessed on 21 April 2016.

  3. Home Office (2015a) Crime Survey for England and Wales 2014/15, accessed on 21 April 2016.

  4. Home Office (2015b), Annual Report on the Home Office Forensic Early Warning System (FEWS), accessed on 21 April 2016.

  5. The Misuse of Drugs Act (1971), accessed on 21 April 2016.

  6. Office for National Statistics (2014), ‘Deaths related to drug poisoning in England and Wales’, accessed on 21 April 2016.

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.Background notes

  1. Quality information

    Further information about the quality of drug-related deaths data can be found in the Quality and Methodology Information (QMI) report.

  2. Mortality metadata

    Information about the underlying mortality data, including details on how the data is collected and coded, is available in the mortality metadata.

  3. Drug poisoning database

    The figures presented in this bulletin have been produced using a special database of deaths related to drug poisoning. This has been developed to facilitate research into these deaths and to aid the identification of specific substances involved. The database is extracted from the national mortality database for England and Wales. Deaths are included if the underlying cause of death is regarded as drug-related, according to the National Statistics definition. More information on this definition and issues relating to the interpretation of drug-related deaths data can be found in Christophersen et al (1998).

    Almost all deaths on the drug poisoning database had a coroner’s inquest. For each death the database includes the following information:

    1. the ICD codes for underlying cause of death and other causes mentioned on the death certificate
    2. every mention of a substance recorded by the coroner in the cause of death section or elsewhere on the coroner's certificate after inquest (up to 7 substances)
    3. an indicator to show if alcohol is mentioned – this includes a wide variety of scenarios ranging from evidence of alcohol consumption around the time of death (for example, an empty vodka bottle found at the scene or alcohol found after toxicology tests) to long-term alcohol abuse and cirrhosis of the liver
    4. other information recorded at death registration such as age, sex, marital status, occupation and place of usual residence
  4. Definition of a drug-related death

    ICD-10 Codes
    Mental and behavioural disorders due to
    drug use (excluding alcohol and tobacco)
    F11–F16, F18–F19
    Accidental poisoning by drugs, medicaments
    and biological substances
    Intentional self-poisoning by drugs,
    medicaments and biological substances
    Assault by drugs, medicaments and
    biological substances
    Poisoning by drugs, medicaments and
    biological substances, undetermined intent
  5. Definition of a death involving legal highs

    This article focuses on substances that were not controlled under the Misuse of Drugs Act 1971 on the day the person died, and are referred to as legal highs throughout this article. The list below shows which substances were included at which time points.

    Deaths occurring on or before
    22 December 2009
    22 December 2009
    15 April 2010
    15 April 2010
    15 April 2010
    15 April 2010
    15 April 2010
    15 April 2010
    15 April 2010
    15 April 2010
    22 July 2010
    4 April 2012
    12 June 2012
    12 June 2012
    12 June 2012
    09 June 2013
    09 June 2013
    09 June 2013
    09 June 2013
    09 June 2013
    09 June 2013
    09 June 2013
    09 June 2013
    23 June 2014
    06 January 2015
    06 January 2015
    4,4’-DMAR 10 March 2015
    26 November 2015
    Not banned
    Not banned
    Not banned
    Not banned
    Not banned
    Not banned
    Not banned
    Not banned
  6. Definition of a death related to drug misuse

    In 2000, the Advisory Council on the Misuse of Drugs published a report called “Reducing Drug Related Deaths” (The Advisory Council on the Misuse of Drugs, 2000). In response to this report’s recommendations on improving the present system for collecting data on drug-related deaths, a technical working group was set up. This group, consisting of experts across government, the devolved administrations, coroners, toxicologists and drugs agencies, proposed a headline indicator for drug misuse deaths as part of the government’s action plan (Department of Health, 2001), to reduce the number of these deaths. This indicator also takes into account the information needs of the European Monitoring Centre for Drugs and Drug Addiction. The baseline year for monitoring deaths related to drug misuse was set as 1999. The definition of the headline indicator using ICD-10 is shown below.

    Cause of death categories included in the headline indicator of drug misuse deaths (the relevant ICD-10 codes are given in brackets):

    a) Deaths where the underlying cause of death has been coded to one of the following categories of mental and behavioural disorders due to psychoactive substance use (excluding alcohol, tobacco and volatile solvents):

    • opioids (F11)
    • cannabinoids (F12)
    • sedatives or hypnotics (F13)
    • cocaine (F14)
    • other stimulants, including caffeine (F15)
    • hallucinogens (F16)
    • multiple drug use and use of other psychoactive substances (F19)

    b) Deaths where the underlying cause of death has been coded to one of the following categories and where a drug controlled under the Misuse of Drugs Act 1971, was mentioned on the death certificate:

    • Accidental poisoning by drugs, medicaments and biological substances (X40–X44)
    • Intentional self-poisoning by drugs, medicaments and biological substances (X60–X64)
    • Poisoning by drugs, medicaments and biological substances, undetermined intent (Y10–Y14)
    • Assault by drugs, medicaments and biological substances (X85)
    • Mental and behavioural disorders due to use of volatile solvents (F18)
  7. Heroin and morphine

    Heroin (diamorphine) breaks down in the body into morphine, so either heroin and/or morphine may be detected at post mortem and recorded on the death certificate. Therefore a combined figure for deaths where heroin or morphine was mentioned on the death certificate is included in Figure 1.

  8. Cocaine

    The figure for cocaine in Figure 1 also includes deaths where cocaine was taken in the form of crack cocaine. It is not possible to separately identify crack cocaine from other forms of cocaine at post mortem. Other evidence to distinguish the form of cocaine taken is rarely provided on death certificates.

  9. Confidence intervals

    Figure 4 shows age-specific mortality rate for deaths involving legal highs, 95% confidence intervals are available in the downloadable Excel datasets. Confidence intervals are a measure of the statistical precision of an estimate and show the range of uncertainty around the estimated figure. Calculations based on small numbers of events are often subject to random fluctuations. As a general rule, if the confidence interval around one figure overlaps with the interval around another, we cannot say with certainty that there is more than a chance difference between the 2 figures.

  10. Special extracts

    Special extracts and tabulations of mortality data for England and Wales are available to order (subject to legal frameworks, disclosure control, resources and agreement of costs, where appropriate). Such requests or enquiries should be made to:

    Mortality Analysis Team
    Life Events and Population Sources Division
    Office for National Statistics
    Government Buildings
    Cardiff Road
    NP10 8XG
    Tel: +44 (0)1633 455341
    Email: mortality@ons.gov.uk

    The ONS charging policy can be found on our website.

  11. Life Events user feedback

    As a user of our statistics, we would welcome your feedback on this publication. Please get in touch either via email at mortality@ons.gov.uk or telephone on +44 (0)1633 455341.

  12. Revisions

    The ONS revisions policy is available on our website.

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Manylion cyswllt ar gyfer y Erthygl

Vanessa Fearn
Ffôn: +44 (0)1633 455341