The population of people injecting drugs in the UK is getting older

The median age of people who inject opiates and crack cocaine is increasing in England, Wales, Northern Ireland, and Scotland, according to a new study published in the journal Addiction. Based on survey data, the researchers concluded that the age of people currently injecting drugs, their age when they first started injecting drugs, and the number of years they had been injecting drugs have all increased.

These increases in age are not due to the general ageing of the population. Rather, they are linked to the ageing of a cohort of young adults who began injecting drugs during an ‘epidemic’ of injection drug use in the 1980s and 1990s, with fewer young adults starting to inject in the years since. The authors also noted geographical differences: for example, the age of participants who had recently injected drugs was youngest in the north-east of England, Lothian and Tayside, and oldest in London and the north-west of England.

The researchers analysed data from two surveys. The first was the Unlinked Anonymous Monitoring survey of people injecting drugs, which collects data through drug treatment and outreach services, needle and syringe programs, and other agencies in England, Wales, and Northern Ireland and has run annually since 1990. The second survey was the Needle Exchange Surveillance Initiative, which has gathered data in Scotland every two years since 2008. In 2018, the last year analysed in this study, approximately 1% of people injecting drugs in the UK were living with HIV.

Across both surveys, three in four participants were male. Most (over 90%) injected heroin. The largest participant groups in England, Wales and Northern Ireland were from the North West, London, and the Southwest. In Scotland, most were from Greater Glasgow and Clyde.

Between 1990-2019, the age of people injecting drugs in England, Wales and Northern Ireland rose from 27 to 40. In Scotland, median age rose from 32 in 2008 to 40 in 2019. The median age of first-time injection drug use also increased: in England, Wales and Northern Ireland, it increased from 22 in 1990 to 26 in in 2008 and 33 in 2019; in Scotland, the increase was from 27 in 2008 to 31 in 2019.

In England, Wales and Northern Ireland, the number of years participants had spent injecting drugs almost doubled in the same period, from seven to 18 years between 1990 and 2019. In Scotland, the number of years spent injecting drugs also almost doubled, from nine to 17 years between 2008-2019.

The cohort effect

A peak in injection drug use in the 1980s and 1990s among young people, and a subsequent decline in new injection drug users, explains the ageing of the population of people injecting drugs in the United Kingdom. In England, the number of people who began injecting drugs almost doubled between 1980 (5470) and 1998 (10,270), then decreased to 2420 in 2019. In Scotland, the number of new injection drug users rose from 1220 in 1980 to 3080 in 1998 before decreasing to 270 in 2018.

The authors suggest that this 1980s/1990s wave of injection drug use, like other epidemics, spread through users’ social networks: in this case, local networks of young people. As a result, the injection drug population at the time was mostly made up of people in their 20s who had been injecting drugs for less than ten years. The 2000s saw a significant change: fewer people started injecting drugs, and the population of people injecting drugs was mostly made of people in their 30s and 40s who had been injecting drugs for 15 years or more. The peak occurred earlier, in the 1980s, in London and the north-west of England, where people injecting drugs are even older today as a result.

This cohort of young people, now decades older, has ‘driven up’ the average age of those currently injecting drugs, and accounts for the increase in the average number of years that people have been injecting. A new wave of young people injecting drugs since the 1990s would have lowered the average age of people injecting drugs as a whole.

Long-term conditions

The UK’s population of people injecting drugs is now made up of older long-term injection drug users with unique health and social needs. Alongside the development of long-term health conditions that become likelier with age within the general population, people injecting drugs face barriers to using health services such as stigmatisation of drug use, a tendency among health care professionals to attribute symptoms to drug use and thus to fail to explore other underlying causes of ill health, and ‘delayed help-seeking’. This older population has a high rate of long-term conditions, for example, chronic obstructive pulmonary disease.

The authors recommend more intensive and effective integration of healthcare services and services supporting people injecting drugs. They also caution us against assuming that because there has not been another wave of drug injection since the 1990s, there will not in fact be another one. They also suggest that another wave would introduce new and different demands on services.