Drug and Harm in the United Kingdom

Researching the Association between Drug and Harm in the United Kingdom

Drug harms in the UK: a multi criteria decision analysis

The article below is part of Frshmind’s “Psychedelic Science Snapshot Series” where Frshminds reviews the latest in psychedelic research.

Original authors:David J. Nutt, Leslie A. King, and Lawrence D. Phillips, on behalf of the Independent Scientific Committee on Drugs
Summarized by: Emily Fewster


Drugs such as alcohol and tobacco products are a major cause of harm to individuals and society, yet are regulated by taxation, sales, and restrictions on the age of purchase. Newly available drugs, and even cannabis have been made illegal or have had laws stiffened in the UK due to concerns about their harms or general safety. Proper assessment of drug harms is needed to provide better guidance and insight to drug policy and law makers, and the present study sought to do exactly that.

Evaluation Criteria for a Drug’s Harm

Taking on such a task is definitely not an easy one, especially due to the many factors that contribute to a drug’s overall harm or safety profile. Experts were asked to score each drug according to nine criteria of harm, ranging from the intrinsic harms of the drugs to social and health-care costs at a 2009 meeting of the UK Advisory Council on the Misuse of Drugs (ACMD) (Nutt et al., 2007). Unsurprisingly, this analysis provoked major interest and public debate, and concerns were raised about the choice of the nine criteria (Murphy, 2007; Britton et al., 2007). To rectify these drawbacks, drug harms were reviewed by key players, experts, and specialists to create an analysis model with the multicriteria decision analysis (MCDA) approach (Dodgson et al., 2000). MCDA explicitly structures and evaluates multiple conflicting criteria in order to lead to more informed and better decisions.

From the first principles and with the MCDA approach, 16 harm criteria were identified (see below for definitions). Nine relate to harm of the individual or user, and seven to the harm of others both in the UK and overseas. These harms were then clustered into five subgroups representing physical, psychological, and social harms (see figure 1).

Drug and Harm in the United Kingdom - chart 1
Figure 1:​ Evaluation criteria organized by harms to users and harms to others, and clustered under physical, psychological, and social effects

In June 2010, a meeting supported by the Independent Scientific Committee on Drugs (ISCD), a new organization of drug experts independent of government interference, was convened to further develop the MCDA model and assess scores for 20 different drugs that are relevant to the UK, and which span the range of potential harms and extent of use (Phillips, 2007). Members had extensive expertise relating to both personal and social aspects of drug harm, and many had substantial research expertise in addiction. All provided independent advice and no conflicts of interest were declared. Harm criterion was scored and the relative importance of each criterion was assessed in an open discussion. This method resulted in a common unit of harm across all the criteria, from which a new analysis of relative drugs harms was achieved.

Harm Criteria and Definitions

  • Drug-specific mortality: ​Intrinsic lethality of the drug expressed as ratio of lethal dose
    and standard dose (for adults)
  • Drug-related mortality: ​The extent to which life is shortened by the use of the drug (excludes drug-specific mortality)—eg, road traffic accidents, lung cancers, HIV, suicide, etc.
  • Drug-specific damage: ​Drug-specific damage to physical health—eg, cirrhosis, seizures, strokes, cardiomyopathy, stomach ulcers
  • Drug-related damage: ​Drug-related damage to physical health, including consequences of, for example, sexual unwanted activities and self-harm, blood-borne viruses, emphysema, and damage from cutting agents
  • Dependence: ​The extent to which a drug creates a propensity or urge to continue to use despite adverse consequences (ICD 10 or DSM IV)
  • Drug-specific impairment of mental functioning: ​Drug-specific impairment of mental functioning—eg, amphetamine-induced psychosis, ketamine intoxication, etc.
  • Drug-related impairment of mental functioning: ​Drug-related impairment of mental functioning—eg, mood disorders secondary to drug-user’s lifestyle or drug use
  • Loss of tangibles: ​Extent of loss of tangible things (eg, income, housing, job, educational achievements, criminal record, imprisonment)
  • Loss of relationships: ​Extent of loss of relationship with family and friends
  • Injury: ​Extent to which the use of a drug increases the chance of injuries to others both directly and indirectly—eg, violence (including domestic violence), traffic accident, fetal harm, drug waste, secondary transmission of blood-borne viruses
  • Crime: ​Extent to which the use of a drug involves or leads to an increase in volume of acquisitive crime (beyond the use-of-drug act) directly or indirectly (at the population level, not the individual level)
  • Environmental damage: ​Extent to which the use and production of a drug causes environmental damage locally—eg, toxic waste from amphetamine factories, discarded needles, etc.
  • Family adversities: ​Extent to which the use of a drug causes family adversities— eg, family breakdown, economic well being, emotional wellbeing, future prospects of children, child neglect, etc.
  • International damage: ​Extent to which the use of a drug in the UK contributes to damage internationally—eg, deforestation, destabilization of countries, international crime, new markets
  • Economic cost: ​Extent to which the use of a drug causes direct costs to the country (eg, health care, police, prisons, social services, customs, insurance, crime) and indirect costs (eg, loss of productivity, absenteeism)
  • Community: ​Extent to which the use of a drug creates decline in social cohesion and decline in the reputation of the community

Drugs were scored with points out of 100, with 100 assigned to the most harmful drug on a specific criterion and 0 indicating no harm. Importantly, each successive point on the scale should represent equal increments of harm. For example, if a drug was scored at 50, then it should be half as harmful as the drug that scored 100. Even more important was the discussion of the group, since scores were often changed as other members shared their different experiences and revised their views. Both during scoring and after all drugs have been scored on a criterion, relativities of the scores were investigated to see whether there were any obvious discrepancies.

It should be noted that some criteria are more important expressions of harm than others, thus the next step was to think about how much that difference in harm matters in a specific context. Greater precision within the context of MCDA was needed to enable the assessment of criteria weighting. To do this, swing weighting was applied, which takes into account the actual difference for a weight change in one criterion compared with other criteria, and the importance of that difference to achieving the overall objective. Members assessed weights within each cluster of criteria, posed as the questions “how big is the difference in harm and how much do you care about that difference?” from 0 to 100. Further, a criterion within a cluster associated with the largest swing weight was assigned an arbitrary score of 100. For example, in the cluster of four criteria under the category physical harm to users, the swing weight for drug-related mortality was judged to be the largest difference of the four, so it was given a weight of 100. The group judged the next largest swing in harm as drug-specific mortality, and that it was 80% as great as drug-related mortality, so it was given a weight of 80. From this example, a computer then multiplied the scores for all the drugs on the drug-related mortality scale by 0.8. After this process, the weightings were compared using the most harmful drug on the most harmful criterion to users and the most harmful drug on the most harmful criterion to others. The result of assessing these weights was that the units of harm on all scales were equated.

Study Results

Drug and Harm in the United Kingdom-chart 2
Figure 2.​ Overall weighted scores for each of the drugs. The coloured bars indicate the part scores for each of the criteria. The key shows the normalized weight for each criterion. A higher weight indicates a larger difference between the most harmful drug on the criterion and no harm. CW=cumulative weight. GHB=γ hydroxybutyric acid. LSD=lysergic acid diethylamide.

The results (see figure 2, above) show the harms of a range of drugs in the UK, with the highest and lowest overall harm scores in the ISCD study being 72 for alcohol and 5 for psilocybin (magic) mushrooms respectively. Alcohol scored fourth on harms to users and top for harms to society, making it the most harmful drug overall. Regarding only the toxic effects, Gable (2004) has shown that alcohol is more lethal than many illicit drugs, such as cannabis, lysergic acid diethylamide (LSD), and magic mushrooms. Results from the current study support these findings.
Scores within one criterion can be to some extent validated by reference to published work. For example, Gable’s study identified a safety ratio (that of an acute lethal dose to the dose commonly used for non-medical purposes) for various drugs. When comparing the ISCD scores on the criterion drug-specific mortality and Gable’s safety ratios of 12 substances in common between both studies, a correlation of 0.66 was found, providing some evidence of validity for the ISCD input scores. Drug-specific mortality estimates were also investigated using studies of human beings (King & Corkery, 2010). The mean fatality statistics from 2003 to 2007 for five substances (heroin, cocaine, amphetamines, MDMA/ecstasy, and cannabis) show correlations with the ISCD scores. Substances that were recorded on the death certificates among other mentions showed a correlation with the ISCD scores of 0.98 and sole mentions of substances on death certificates showed a correlation of 0.99, nearly a perfect positive correlation, providing further evidence of validity to the ISCD scores.

Regarding the criterion of dependence, the correlation between ISCD scores and lifetime dependence reported in a US survey by Anthony and co-workers (1994) was 0.95 for five drugs (tobacco, alcohol, cannabis, cocaine, and heroin) investigated in both studies, showing the validity of the input scores for those substances.

Social harms are harder to ascertain, although estimates based on road traffic and other accidents at home, drug-related violence (Werb et al., 2011), and costs to economies in provider countries (eg, Colombia, Afghanistan, and Mexico) (United Nations Office of Drugs and Crime, 2010) have been estimated. However, since data is not available for many of the criteria, the expert group approach is the best possible alternative that can be provided.

The issue of the weightings is vital since they affect the overall scores. Although the assessed weights were agreed upon by a panel of experts, they cannot be cross-validated with objective data. However, the effect of varying the weightings was explored through sensitivity analysis, a method that determines how target variables are affected based on changes in other variables. For example, it was found that in order for heroin to displace alcohol’s first position of overall harm, an increase to the weight on drug-specific mortality or on drug-related mortality by more than 15 points was needed. Similarly, a large change in the weight on drug-specific damage from about 4% to slightly more than 70% would be needed for tobacco to displace alcohol at first position. Further, in order for crack cocaine to achieve the overall most harmful position, an increase in the weight of harm to users from 46% to nearly 70% would be necessary. Extensive sensitivity analyses on the weights showed that this model is very stable and that large changes, or combinations of modest changes, are needed to drive substantial shifts in the overall rankings of the drugs.

Limitations of this approach include the fact that only harms of the drugs were scored. Initially, all drugs provide some benefits to the user, otherwise there would be no motivation for consumption. However, these benefits may attenuate overtime with frequency of use, tolerance and withdrawal, depending on the specific drug. Therefore, further exploration into these factors is needed. Some regulated drugs such as alcohol and tobacco have commercial benefits to society in terms of providing work and tax, which to some extent offset the harms (Lloyd & McKeganey, 2010). In many cases, specific drug harms are affected by the drugs availability and legal status, thus these results are not necessarily applicable to countries with very different legal and cultural attitudes to drugs than the UK. Ideally, a model is needed to distinguish between the harms resulting directly from drug use and those resulting from the control system for that drug.

Finally, a low score in this assessment does not mean the drug is not harmful, since all drugs can be harmful under specific circumstances.
Correlations between overall scores from this study and the classification of drugs based on revisions to the UK Misuse of Drugs Act (1971) is 0.04, showing that the present drug classification systems have virtually no relation to the evidence of harm. Findings also support the conclusions of expert reports (NICE, 2010; House of Commons Health Committee, 2010), that being a clear need to tackle the public harms related to alcohol. Importantly, it should be acknowledged with concern that the lead investigator of this study and the UK government’s former chief drug advisor David J. Nutt was asked to resign as chair of the ACMD [Advisory Council on the Misuse of Drugs] by the former UK home secretary in response to his stance, supported by this paper’s findings, that ecstasy (MDMA) and LSD are less dangerous than alcohol or tobacco. This event should call into question the motivations of those involved with drug-policy and law making. Richard Garside, director of the centre for crime and justice, said Nutt’s paper gave an insight into what drug policy might look like if it was based on the research evidence rather than political or moral positioning. He also added “the home secretary’s action is a bad day for science and a bad day for the cause of evidence-informed policy making” (Tran, 2009). Aside from the data presented on drug harms, a take-way from this paper (or rather the events that succeeded its publication) should be for drug policy and law makers to align themselves with science, data, and the betterment of public health overall as opposed to political ideologies or hedonistic greed.


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Tran, M. (2009, October 30). ​Government drug adviser David Nutt sacked.​ The Guardian. https://www.theguardian.com/politics/2009/oct/30/drugs-adviser-david-nutt-sack ed

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Werb, D., Rowell, G., Guyatt, G., Kerr, T., Montaner, J., & Wood, E. (2011). Effect of drug law enforcement on drug market violence: A systematic review. International Journal of Drug Policy,​ ​22(​ 2), 87-94. https://doi.org/10.1016/j.drugpo.2011.02.002

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Emily Fewster

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Passionate about studying the psychedelic/mystical experience from a neuropsychological lens :)

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