Treatment for drug abusing offenders: the view from Europe

Regular readers of the blog will be familiar with much of what’s currently known about how best to treat people with drug problems. Unfortunately, because so much research on that topic originates in North America, European policymakers can sometimes be left in a tricky position: either they assume that research conducted elsewhere applies similarly their side of the ocean (a justifiable assumption in some cases, to be sure), or they throw their hands up in exasperation. This problem is much less acute when we’re dealing with research on specifically medical interventions, where European research is up-to-par (and indeed superior) in many areas. But when we’re dealing with the criminal behaviours of people with drug problems, much less research comes from Europe.

Some colleagues and I recently published a study in the journal Psychology, Crime & Law that hopefully goes some way towards addressing this problem (link here for those with a journal subscription; otherwise, feel free to email me if you’d like a pdf version). We conducted a meta-analysis on the effect that treatment programmes applied to drug abusing offenders had on crime, health, and drug use outcomes. The hope was to collect everything on the topic that would give a sense of the evidence base, as long as it emanated from Europe.

After combing through nearly 40,000 titles, we found only 15 studies that were sufficiently rigorous to exclude common threats to validity (e.g., roughly equivalent comparison groups, etc). Moreover, those studies came from only six countries (eight were from the UK). Even within Europe, there’s a tremendous regional disparity in who’s doing the research on which other countries rely.

The results showed that there was a clear positive effect of treatment on criminal behaviours, illicit drug use, and physical health. Assuming a base rate of reoffending of 50%, the results corresponded to an average reduction of reoffending of 37% in the treatment groups compared to the control groups. Results were somewhat more mixed for psychological health outcomes, and for illicit drug use after we disaggregated the outcomes based on particular types of drugs.

One of the main conclusions of the paper will not be news to those who follow what others on this blog have been saying for years. If we can persuade policymakers to endorse the proposition that the quantity of drugs consumed might not need to change in order to 1) decouple the drug-crime connection, 2) provide a safe, stable position in which to manage other complications arising from someone’s drug addiction, then we might be able to make serious progress.

For those who wondered whether European evidence points in a similar direction to North American research, this paper suggests that it does. In fact, the results of our meta-analysis are even more positive than what was observed in previous reviews. However, this should be taken cautiously, both because of the erratic properties of small sample sizes, and because of the over-representation of evaluations of pharmacological substitution treatments in our sample (which generally show particularly good effects).

If you’d like a copy of the paper, but you don’t have journal access, you’re welcome to email me at [myfirstinitial][koehler][@][berkeley]”dot”[edu]

10 thoughts on “Treatment for drug abusing offenders: the view from Europe”

  1. “After combing through nearly 40,000 titles, we found only 15 studies that were sufficiently rigorous to exclude common threats to validity..”
    It sounds as if quite a few countries could save themselves a lot of money simply by tightening up the review criteria for research funding. Some studies are inconclusive because the numbers turned out other than was reasonably expected; others are so ill-designed that no results could attain reliable statistical significance. Researchers can always resubmit a revised proposal, so rigour could raise standards generally.

  2. I had the same reaction as James to these two (disappointing) numbers. But many of those studies — indeed probably most of them — were not centrally funded so that probably isn’t the key choke point.

  3. I see similar issues with California legislation. People seem to make the same mistakes over and over again, and it seems like some group of experts could easily come up with a 2 or 3 page piece on What Not To Do. Grantmakers could just require them to read it first before submitting. Who knows, maybe it would help. And, maybe it’s been done already. I wouldn’t know.

  4. To be clear: does the term “drug abusing offenders” here include people who take cannabis?

    I see lots of political gaming of terms like “drug abuse”. Especially as it concerns cannabis use.

    In the USA, most (government) people (with a paycheck dependent on continuing pot prohibition) take that (“drug abusing offenders”) to definitely and without doubt include anyone who is caught or admits to using any amount of cannabis in any way at any time.

    Is that is meant by “drug abusing offenders” here, also - anyone who is caught with or uses cannabis?

  5. Well, OB, cannabis is more addictive than the hallucinogens and about the same as alcohol. The Netherlands has the highest demand for cannabis treatment, by the way, due to the problems of their policies. So what of it?

    And this whole “paycheck dependent on continuing pot prohibition” is a massive joke. If marijuana was legal, THE TREATMENT INDUSTRY AND COPS AND OTHERS WOULD HAVE MORE BUSINESS—NOT LESS. Can you argue that because alcohol is legal, those in the public (or private) sector do not benefit from the problems that result or simply the regulation that it has to endure? Get real.

    1. The demand for opioid treatment in the Netherlands, however, is very low (15.8% vs 59.3% in the UK vs 24.8% in Sweden).

      If people are becoming addicted to cannabis instead of opioids, then that’s a good thing.

    2. re: “Can you argue … Get real.”


      Go back and read my simple question which you did not answer.

      Question: To be clear: does the term “drug abusing offenders” here include people who take cannabis?

      1. Answer: It could have, as we were willing to include such studies in our final sample. However, we didn’t find any evaluations of treatments designed specifically for cannabis-using offenders that fulfilled the eligibility criteria.

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