Are 1.5 million people 'addicted' to prescription drugs?

"There are currently 1.5 million people addicted to prescription drugs in the UK."

Keith Vaz MP, Chairman of the Home Affairs Select Committee

Drugs were high on the news agenda today after the Home Affairs Select Committee published its latest report into legal highs and prescription drugs. This morning the BBC led with:

"Up to 1.5 million people could be addicted to prescription drugs and the problem must be dealt with urgently, a group of MPs has said."

By this afternoon, the sentence was gone without a trace. What happened?

A look at the Committee's report itself gives away a clue. It said that:

"We welcome the work of the All Party Parliamentary Group [APPG] for Involuntary Tranquilliser Addiction and are deeply concerned by their estimate that there are currently 1.5 million people addicted to these type of drugs".

With more detail, the claim actually looks more specific: 1.5 million people are supposedly addicted to tranquillisers (drugs that tend to have a sedative effect such as Temazepam or Diazepam). These are a type of prescription drug but by no means the only one. For instance, SSRIs are a group of prescribed drugs that treat depression, but they're not tranquillisers.

Leaving aside this confusion, another question is where this 1.5 million figure came from. We contacted the APPG for Involuntary Tranquilliser Addiction and Public Health England who kindly directed us to the sources.

There are two. Back in 2001, a poll for BBC Panorama found that 3% of 2,000 adults surveyed had been taking a benzodiazepine tranquillisers on prescription for longer than four months. Based on the 2001 adult population, that's about 1.5 million people taking the drugs for this long.

The second: a research paper from 2004, found 1,300 patients at GP practices in Newcastle and North Tyneside were taking benzodiazepine tranquillisers for longer than six months. Again, applied to the national picture based on the number of GP practices across the country, this works out at roughly 1.5 million people.

In spite of both bits of research agreeing on the same number, Public Health England didn't think much of the statistic when we spoke to them:

"we wouldn't support the figure ... it's not a valid figure to be using"

It's certainly an old figure based on applying samples to a national picture, but that's not the only issue. It's much more difficult to stand the figures up when the term 'addiction' is applied to define them.

Taking tranquillisers such as benzodiazepines was considered unsuitable beyond 2-4 weeks by the Committee on Safety of Medicines 25 years ago, and that limit remains in local practice guidance today. So it's possible to understand the idea that 'long-term' users are the cases that need to be measured.

Whatever the number, calling them 'addicted' is much more controversial. Asides from exceptional individual cases, it's difficult to determine the extent of a person's addiction to their prescription. NHS guidance recognises the possibility that addiction can happen within a few weeks of being on a tranquilliser, but doesn't suggest that anyone on these drugs for longer than four weeks is necessarily addicted.

Update (9 January 2014)

APPGITA has published its own explanation of the sources on its website, which is very welcome.