Illicit drugs are a substantial threat to the public good, not only because they adversely affect public health, but also because they can generate crime, disorder, family breakdown, and community decay. The diverse policies and programmes to ameliorate these problems vary substantially in their effectiveness. Here we review effective interventions to draw attention to the drug-control policies available to governments, in much the same ways as evidence has contributed to debates about more effective tobacco and alcohol policies.
Building on the first paper in this series,1 which assessed the extent to which illicit drug use contributes to the global burden of disease, we critically assess the scientific basis of interventions intended to prevent or at least minimise the damage that illicit drugs do to the public good. We examine the quality of evidence for different policies, estimate the likely magnitude of their effects, assess potential unintended consequences, and identify promising areas for future investment into research and interventions. We can thus help policy makers make informed decisions about which policy options will maximise the public good. By the public good we refer to social benefits such as better public health, reduced crime, and greater stability and quality of life for families and neighbourhoods. Contemporary drug-related public policy attempts to promote the public good through a broad range of administrative actions designed to prevent the initiation of drug use by non-users, help heavy drug users change their behaviour or reduce the consequences of their drug use, and control the supply of illicit drugs (and the supply of diverted prescription drugs used for non-medical purposes) through laws, regulations, and enforcement.
Much public debate in drug policy is only minimally informed by scientific evidence. Values and political processes (eg, voting) are important drivers of drug policy, but evidence of effectiveness and cost-effectiveness can help the public and policy makers to select policies that best achieve agreed goals.
For the formulation of drug policy, coordination of different methods of study and analysis from different scientific subject areas is needed. Interpretation of this evidence will depend not only on study design and magnitude of effect, but also on the relevance and generalisability of the findings. In addition to the assessment of new interventions and strategies, examination of the costs and benefits of policy measures that might mistakenly be assumed effective is also important.
Key messages
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Drug policy should aim to promote the public good by improving individual and public health, neighbourhood safety, and community and family cohesion, and by reducing crime.
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The effectiveness of most drug supply control policies is unknown because little assessment has been done, and very little evidence exists for the effectiveness of alternative development programmes in source countries.
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Supply controls can result in higher drug prices, which can reduce drug initiation and use but these changes can be difficult to maintain.
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Wide-scale arrests and imprisonments have restricted effectiveness, but drug testing of individuals under criminal justice supervision, accompanied by specific, immediate, and brief sentences (eg, overnight), produce substantial reductions in drug use and offending.
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Prescription regimens minimise but do not eliminate non-medical use of psychoactive prescription drugs. Prescription monitoring systems can reduce inappropriate prescribing.
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Screening and brief intervention programmes have, on average, only small effects, but can be widely applied and are probably cost-effective.
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The collective value of school, family, and community prevention programmes is appraised differently by different stakeholders.
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The provision of opiate substitution therapy for addicted individuals has strong evidence of effectiveness, although poor quality of provision reduces benefit. Peer-based self-help organisations are strongly championed and widely available, but have been poorly researched until the past two decades.
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Health and social services for drug users covering a range of treatments, including needle and syringe exchange programmes, improve drug users' health and benefit the broader community by reducing transmission of and mortality due to infectious disease.
We examine evidence of good scientific quality that can inform decision-making about drug policies that can be introduced, modified, expanded, reduced, or stopped. This includes scientific evidence for the likely benefits to the public good. Some of the evidence comes from randomised trials and quasi-experimental designs with similar control conditions.
We also consider other types of evidence when randomised controlled trials could not be implemented or would be politically challenging to implement. This includes natural policy experiments (ie, observational studies done to assess the effect of policy interventions) and time-series analyses. In some policy domains, such studies provide the best available scientific evidence. For each of the five broad policy approaches that we discuss, we first identify the relevant activity, and also the objective (table 1).
