Getting higher: has mephedrone use increased by 300% since it was banned?

"Banning the designer drug mephedrone resulted in a 300% increase in its use. Banning khat is likely to have the same effect."

Paul Flynn MP, House of Commons, 15 July 2013

Last month the UN reported that the UK was the largest market for legal highs in the EU, one more marker of long-standing concern which even extends to fictional drugs.

A number of substances have been banned by the current and previous governments, with the stimulant khat recently announced as the latest addition to the list of controlled substances.

Mephedrone became a Class B substance in April 2010, after news coverage linked it to the deaths of a number of young people. Since then possession of the synthetic stimulant — also known as meow meow or MCAT — has been punishable with a maximum sentence of five years, or 14 years for dealing.

Did banning it lead to a rise in use?

Paul Flynn's office pointed us to this article in the Guardian from September 2012, which cites figures from police in South Wales apparently showing that the number of 'offences linked to mephedrone use' rose more than 400 per cent in 12 months.

Mr Flynn confirmed that the suggestion that banning khat will lead to similar increase in usage was a statement of his opinion.

Does it stack up?

Comparing Mr Flynn's statement to the news report alone, there are several ways in which the claim appears unsupported.

Firstly, the police figures cited in the news article show a greater increase than that reported by Mr Flynn — 400 per cent versus 300 per cent. Using the article alone as a source in Parliament was a risk, as it doesn't tell us whether this was a rise of 1 to 5, or 1,000 to 5,000.

More importantly, the police figures relate to 'offences linked to mephedrone use', while Mr Flynn's claim relates to usage. The two clearly aren't the same, and the distinction is important: the number of offences recorded by the police could be influenced by a number of factors, of which underlying usage levels is only one — for example, police targeting of certain types of offences, or potentially police getting increasingly efficient at enforcing the ban as the figures relate to the years immediately after its introduction.

Finally, Mr Flynn's statement in the Commons would give the impression to those hearing it that this is a nationwide trend, when in fact we're talking about only one area of the country.

Searching for other references to the police figures, another news story gives more detail on what seems to be the same police claim. This sets out that the figures related only to the county of Carmarthenshire, and that the increase recorded was from 21 offences 'involving either use or possession of mephedrone' between April 2010 and March 2011, to 106 offences in the same period the following year. That's what we found in the original source, a press release from Dyfed-Powys Police.

We therefore have figures from only one South Wales county being relayed as representative of the whole country, and purely looking at the number of offences after the ban was brought in, not the "usage" referenced by Mr Flynn.

Better data?

So what can we say with confidence about mephedrone use? Turning first to official statistics, there are two data sets put out by the Government which offer some insight.

1.4 per cent of the 16 to 59 year olds population had used mephedrone during 2010/11, going down to 1.1 per cent the next year, according to the Crime Survey for England and Wales. The decrease of 0.3 percentage points is described as being statistically significant.

What the data doesn't show us is what usage of the drug was before it was banned in April 2010 — the survey only started asking questions on mephedrone use for the first time in 2010/11. But the period covered by the figures is the same as that in the police figures cited by Paul Flynn, so offers a useful counterpart to those figures, giving quite a different picture.

While legal at the time of being carried out, the survey also asked respondents about use of khat, and found that 0.2 per cent of the 16 to 59 population had used the stimulant in 2011/12, unchanged from 2010/11.

The other key government data source that gives a sense of changes in the drug trade — but not directly to usage — is Home Office data on seizures in England and Wales. Mephedrone isn't reported on separately, but the 'other class B' category in which it is reported saw an increase in by the police from 321 in 2009/10 to 2,477 in 2010/11.

The only change in this period was the banning of mephedrone and other cathinone-based drugs, but clearly it would be wrong to assume this increase in seizures mirrors an increase in usage — the drug was being used up to April 2010, but, being legal up to that point, would not have been subject to seizure by the police.

What the seizure data can tell us, though, is that seizures of 'other class B' drugs increased by to 3,067 in 2011/12, or by 24 per cent. While unclear exactly how much of this related to mephedrone, the figures cast further doubt on any view that the 400% increase in mephedrone offences in Carmarthenshire between 2010/11 and 2011/12 was representative of trends in usage across the country in this period.

The big picture

There was a 400 per cent increase in recorded offences related to mephedrone in Carmarthenshire from 2010/11 to 2011/12, but usage across England and Wales as best we can measure it actually decreased during this period, while seizures data also suggests no increase of this kind of scale.

What isn't available, though, and what would allow more concrete conclusions to be drawn on the impact of the ban on use of mephedrone, is reliable usage data covering the periods both before and after the ban was brought in.

Even if such figures existed and showed an increase, there are limits to the conclusions that could be drawn. It would not be possible to prove the causal link that Mr Flynn suggests — that the ban directly led to an increase — as there could be other factors at play.

What might happen with khat, which is currently used by just 0.2% of 16-59 year olds, is even more a matter for speculation.

Press reports of very specific figures aren't a great basis for MPs to work from for making national policy. Our sources list offers a starting point for researchers looking for better ones and we're always happy to help any MPs' office find the right source, so please contact us if we can help.

Footnote: those fictional drugs are a serious issue. 0.1% of children confessed to taking the made up drug 'Semeron' when surveyed about drug use. It's a trick question so that their answers can be excluded from the survey results.

UPDATE 11:27: This article was updated to clarify what the Dyfed-Poyws Police figures related to.

UPDATE 20 Jul: Thanks to a reader suggestion, this article was updated to note the possibility that the new legislation coming into force at the beginning of the period the figures relate to may have led to gradual changes in police practice.