In December 2007, in the Journal of the Royal United Services Institute (RUSI), I highlighted an increased cocaine positive rate in the British Army between 2003 and 2007. I’d relied on answers to parliamentary questions by the late Lord Garden and Patrick Mercer MP.

Was the hike in cocaine rate an artefact, a real public health concern or just a reflection of civilian life? It would be a health concern if cocaine use was a reaction to combat stress.

But the army was getting ever smarter at detection, by using a more sensitive cocaine-test and testing preferentially:

•   on Mondays – after weekend home leave (cannabis stays in the urine for around two weeks, but cocaine and ecstasy for a few days only)                
• younger soldiers, typically privates – who are more recently recruited and from the age-group in which civilian drug use is highest, or
• selected units or individuals – because of historically high detection rates, or other intelligence.

All of these changes happened between 2003 and 2007, and muddied the analytical waters.
 
A new analysis, efficiently and promptly published, took a revised cocaine threshold, as well as rank and weekday of test into account. It revealed that the increase in cocaine positive rate had already levelled off in 2005 – before major combat in Afghanistan. Also, whereas privates’ cocaine positive rate on Mondays in 2007 was around 10 per 1,000 tests, it had halved by Wednesdays. This strongly indicated that soldiers’ cocaine use was off-duty at weekends, not dependency.
 
The 2008 analysis also confirmed that the army conducts compulsory drug tests with exemplary efficiency. The major drop in its cocaine positives, which we now see ( in today’s Independent and table below), was not due to any let-up on detection, which the army hell-bent on. The cocaine rate has halved from around 4.7 positive for cocaine per 1,000 tests in 2006-2008 (95 per cent CI: 4.4 to 5.0) to 2.3 per 1,000 tests in 2009. The ecstasy positive rate has also fallen dramatically in 2008 and 2009.
 
However, the army’s compulsory tests do not include mephedrone, a "legal high", which is cocaine-like. Have soldiers (and civilians) substituted mephedrone for cocaine?
 
Soldiers and civilians now need to know about the relative harms of cocaine, ecstasy and  mephedrone:  including lethality. The only way to learn about the lethality of mephedrone is if, as a matter of routine, we start testing for its presence at all drug-related deaths in the UK in a 6-month period. For the sake of public health, this testing should be done.