April 16, 2014

Ways not to use the Global Drug Use Survey

We learned previously from Stuff and the Global Drug Use Survey that 22% of New Zealanders have used synthetic cannabis. Today

Results from this year’s Global Drug Survey, conducted in partnership with Fairfax Media, found almost 4 per cent of synthetic cannabis users sought emergency medical treatment. More than a quarter of those were admitted to hospital.

It simply cannot be true that 4% of 22% of the country has sought emergency treatment after using synthetic cannabis. Even restricting to adults, that’s 30,000 people, with more 7,500 admitted to hospital. In the most recent year for which I can find data (2010-11, when the drugs were more widely available than now) there were 672,000 publicly funded hospital admissions for all causes, and of those, only 896 were for cause categories X41 & X42, which would include all synthetic cannabis cases plus many others.

[update: fixed typo in numbers]

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar

    4% of GDS respondents who said they had used synthetic cannabis??

    GDS was a self-selecting survey. And I think Fairfax had said so in its earlier reporting. But yes, sloppy.

    10 years ago

    • avatar
      Thomas Lumley

      No, 22% said they had used, 4% of those reported seeking emergency medical assistance.

      10 years ago

  • avatar

    Thanks v. much for shining a light on the ongoing debacle that is the war on drugs ; that blatant propaganda continues to drive a dysfunctional public policy after 80 years is both mindboggling & disturbing ! A case of politics held hostage by a paradigm of blind fear.Where are all the other academics who should be weighing in on these issues !

    10 years ago

  • avatar
    Brian Orax

    The article says “22 per cent of New Zealanders surveyed”.

    This is NOT the same as 22% of the population.

    The GDS is extremely self selecting for people who already use drugs. It might be somewhat accurate to say that 22% of NZ drug users have also tried SCRAs, but as far as I can tell, they are not claiming the thing that you say they are.

    8 years ago

    • avatar
      Thomas Lumley

      The site is down for maintenance, and I didn’t keep a screenshot, but I’m pretty sure it was reported in the same way as other surveys that do claim their numbers have some generalisable meaning.

      I’m not against the GDS, I just think it’s most useful for comparisons between drugs and information about risk-management strategies, and that the overall use percentages are pretty meaningless. The Fairfax papers keep highlighting the overall use percentages, which aren’t even reweighted to reduce the bias.

      The *useful* information in that story is the comparison of proportion needing medical assistance between cannabis and the synthetics.

      8 years ago