Variation in global estimates of the prevalence of injecting or opioid use from recent reports are partly explained by use of alternative information sources and value given to unreferenced country estimates; but also highlights a prevailing problem with the reporting and robustness of prevalence estimates. Unfortunately, there is no quick solution: we need investment both in ongoing information or surveillance of drug related harms and clinical and other interventions and in the implementation of more refined statistical methods to estimate prevalence.
Keywords: Global; World Drug Report; global estimates; indirect estimation; injecting drug use; opioids; people who inject drugs; prevalence.