Hines LA, Trickey A, Leung J, et al. - Data from a formerly published global systematic review done in April 2016 was pooled in this global systematic review and meta-analysis in order to examine global difference in the age profile of people who injected drugs (PWID), identify country-level factors related to age of PWID, and evaluate the relationship between injecting drug use (IDU) in young people and rates of injecting and sexual risk behaviors at the country level. They found a difference in the age profile of PWID was correlated with GDP and urbanization. To restrict the spread of blood-borne viruses, regions with the greatest prevalence of young PWID (aged ≤ 25 years) had low coverage of interventions. Moreover, in the monitoring of PWID populations, data quality reflected the demand for enhancements.