Research carried out by the universities of Bristol, Cambridge and Edinburgh found that opiate substitution treatment reduced the frequency of drug use and led to a drop in the risk of death by 13 per cent each year.

However, the study also showed that treatment did not reduce the overall duration of injecting.

The team analysed the drug use patterns of almost 800 injecting drug users in Edinburgh from 1980 to 2007.

The team say the findings support the long term use of opiate substitution treatment (methadone), even in those who continue their drug use.

Heroin, by injection, is an important public health problem, affecting about one per cent of young adults in the UK. It raises a person’s risk of death by over ten times that of the general population. Injecting heroin use is responsible for many deaths from overdose every year and can transmit HIV and Hepatitis C and B viruses. A recent outbreak of anthrax in Scotland caused 13 deaths in injecting drug users.

Researchers found that those prescribed methadone reduced their frequency of injecting drugs, however, the overall number of years of injecting was prolonged compared to people who received little or no methadone.

Researchers also found that a history of imprisonment was associated both with an increased risk of death and a longer duration of injecting. 

Dr Roy Robertson, a general practitioner who led the study at the University of Edinburgh, said: “These results confirm that methadone works and works best when prescribed for as long as is needed in what is a chronic condition. The effects of methadone on long-term injection cessation will probably not be particularly surprising for experienced clinicians. Many injectors on a prescription will continue to occasionally inject though may be reluctant to acknowledge this to their doctor for fear of a punitive response.

“Our research shows that despite this they still gain substantial health benefits from their prescription.  Suggestions that methadone prescribing should be cut back or confined to the short-term are clearly misplaced and would lead to poorer health for drug injectors.”

Injecting drug use is a common, chronic condition associated with substantial excess death and illness. The main treatment is methadone or other forms of opiate substitution therapy.

The research advances the evidence base on the natural history and impact of treating injecting heroin use in two ways.

First, previous studies have shown only that treatment improves survival over the short-term. Second, it has been thought that methadone reduces the risk of death by providing a faster route to full recovery and abstinence. 

The new study shows that lives are saved over the long-term, but not necessarily through reducing the overall duration of injecting.  Evidence from other studies suggests that methadone and other opiate substitution treatments also reduce the risk of blood borne infections, such as HIV and Hepatitis C, and reduce drug related crime. 

The implications for policy are that there is a balance between saving lives and achieving abstinence from injecting heroin use and that the improvements in survival and other outcomes increase with length of treatment. 

Seven hundred and ninety four people took part in the study, of whom 571 were still alive at the start of the follow-up and 432 (75 per cent) were interviewed. By the end of the follow-up, five of those interviewed had died, bringing the total number of deaths to 228 (29 per cent). The researchers were able to follow-up 655 (82 per cent) using primary care records, including for 187 (82 per cent) of those who died. One hundred and thirty nine (18 per cent) participants were lost to follow-up.

The study is available online and will be published in the BMJ on 17 July. The research was funded by the Chief Scientist Office.

Paper: Survival and cessation in injecting drug users: prospective observational study of outcomes and effect of opiate substitution treatment, Jo Kimber, Lorraine Copeland, Matthew Hickman, John Macleod, James McKenzie, Daniela De Angelis, James Roy Robertson, BMJ, published online ahead of print 1 July 2010.