Associations between national development indicators and the age profile of people who inject drugs: results from a global systematic review and meta-analysis

Lindsey A Hines, Adam Trickey, Janni Leung, Sarah Larney, Amy Peacock, Louisa Degenhardt, Samantha Colledge, Matt Hickman, Jason Grebely, Evan B Cunningham, Jack E Stone, Kostyantyn Dumchev, Paul Griffiths, Peter Vickerman, Richard P Mattick, Michael T Lynskey

Research output: Contribution to journalArticle (Academic Journal)peer-review

18 Citations (Scopus)
127 Downloads (Pure)


Background: Globally, there are an estimated 15.6 million people who inject drugs (PWID). We describe global variation in age indicators of PWID, identify country-level factors associated with age of PWID, and explore whether youth injecting drug use (IDU) associates with rates of injecting and sexual-risk behaviours at country-level.
Methods: A global systematic review collated data on the percentage of young PWID, IDU duration, average age of PWID, average age at IDU initiation, and percentage reporting sexual/injecting-risk behaviours. World Bank data were used for development indicators. Hypotheses were tested through generalized linear models.
Findings: Globally, 25.3% (95% Uncertainty Interval [95%UI]: 19.6-31.8) of PWID were aged ≤25 years. Eastern Europe had the highest percentage of young PWID (43.4%, 95%UI: 39.447.4%), Middle East and North Africa had the lowest (6.9%, 95%UI: 5.1%-8.8%). At the country-level higher GDP was associated with longer median injecting duration (0.11 years per $1000 GDP increase, 95% Confidence Interval [95%CI]: 0.04-0.18), and older median age of PWID (0.13 years per $1000 increase, 95%CI: 0.06-0.20). Urbanisation growth was associated with higher age at IDU initiation (1.40 years per annual percentage change, 95%CI 0.41-2.40). No associations are observed between indicators of youth IDU and country-level youth unemployment, GINI, or OST provision. There was no evidence for associations between injecting/sexual-risk behaviours and age of PWID.
Interpretation: Variation in the age profile of PWID is associated with GDP and urbanisation. Notably, regions with the highest prevalence of PWID aged ≤25 years have low coverage of interventions to prevent blood-borne virus spread. Data quality demonstrates required improvements in monitoring.
Funding: Australian National Drug and Alcohol Research Centre, Australian National Health and Medical Research Council, Open Society Foundation, WHO, the Global Fund, UNAIDS, NIHR HPRU EI, The Wellcome Trust.
Original languageEnglish
Pages (from-to)e76–e91
Number of pages16
JournalLancet Global Health
Issue number1
Publication statusPublished - 1 Jan 2020


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