Illicit use of opioids is higher than estimates from the federal government. That conclusion comes from a new study by the Rand Corporation and University of Southern California. That survey of American adults reports eleven percent used illicit opioids in the past year, including illicit fentanyl— twenty times greater than estimates from a federal study. Most people who used non-prescription opioids named fentanyl use. Among the reasons for such a difference could be in the way the questions about illicit drug use were asked. Nonetheless, researchers found the differences disturbing and in need of further investigation in order to better understand where we are in the opioid epidemic. The study is published in the journal JAMA Health Forum.