Deaths by drug overdose in the United States increased by more than 17% in 2016, according to a report released Friday by CDC. Preliminary data from the 50 states show that from the fourth quarter of 2015, through the fourth quarter of 2016, the rate of fatal overdoses rose to nearly 20 people per 100,000 from 16.3 per 100,000. CDC had previously estimated that about 64,000 people died from drug overdoses in 2016. Robert Anderson, MD, chief of CDC's mortality statistics branch, says in recent years the deaths have been driven by overdoses of synthetic opioids, mostly fentanyl, rather than heroin. The report's results are preliminary. Although the report includes deaths by cancer, heart attack and most other causes through mid-2017, its section on drug deaths covers only 2015 through 2016, because of the complexity of toxicology reports and other information needed to confirm drug overdoses. The number of teenagers becoming addicted to opioid analgesics is going down, notes Andrew Kolodny, MD, director of opioid policy research at Brandeis University. But those who are already addicted, in their 20s and 30s, are increasingly in danger because of the practice of mixing heroin with fentanyl or fentanyl being sold as heroin. Other government reports show that deaths by fentanyl have increased significantly in 3 years.