In the largest study of opioids users ever undertaken, the researchers used records of 198,247 people in England who had been involved in drug treatment or the criminal justice system between 2005 and 2009. The data recorded 3,974 deaths and their causes during this period. Opioid users were six times more likely to die prematurely than people in the general population. Almost one in ten of these deaths were due to suicide, more than four times the rate in the general population.
The study is the first to record age trends in opioid users' mortality and the results demonstrate that many health inequalities between users and the general population widen with age. In the oldest 45-64 age-group, homicide was 27 times more common than would be expected in the general population.
The most common cause of death was drug poisoning and the risk of this increased as users got older: Dr Tim Millar from the University's Centre for Mental Health and Risk led the study. "Crucially, opioid users need to hear this new information on overdose, to emphasise that their risk of overdosing increases as they get older.
"This group is also one of the most vulnerable to homicide - at a rate which is staggeringly higher than in the general population. It is apparent that older users of opioids are one of the most vulnerable groups in society, yet most treatment programmes don't differentiate by age."
The study also highlighted other major causes of death - circulatory disease, respiratory disease (such as pneumonia) and liver diseases all featured prominently and are much more common among opioid users than in the general population.
The research acknowledges that drug users are often in situations with poor diet and housing and may have other addictions such as smoking or alcohol which are not taken into account in this research. However, by adopting a methodology which doesn't just include people who have sought treatment, the study incorporates more users than has been possible before.
Dr Millar said: "In the UK, we are seeing the large number of people who became users during the 80s and 90s getting older. As these users get older, the health gap between them and the wider public increases, so much more work is needed to develop specific programmes which focus on treating and informing this group."
The study, 'National record linkage study of mortality for a large cohort of opioid users ascertained by drug treatment or criminal justice sources in England, 2005-2009', was published in the journal Drug and Alcohol Dependence.