Trends analysis of drug poisoning deaths has helped explain a national epidemic of overdose deaths in the USA that began in the 1990s, concludes Leonard Paulozzi and colleagues at the Centers for Disease Control and Prevention in Atlanta, USA. The contribution of prescription pain killers to the epidemic has only become clear recently. This research is published this week in the journal, Pharmacoepidemiology and Drug Safety.

Drugs called "opioids" are frequently prescribed to relieve pain, but if abused they can kill. Over the past 15 years, sales of opioid pain killers, including oxycodone, hydrocodone, methadone and fentanyl, have increased, and deaths from these drugs have increased in parallel.

In 2002, over 16,000 people died in the USA as a result of drug overdoses, with most deaths related to opioids, heroin, and cocaine. Opioids surpassed both cocaine and heroin in extent of involvement in these drug overdoses between 1999 and 2002.

The situation appears to be accelerating. Between 1979 and 1990 the rate of deaths attributed to unintentional drug poisoning increased by an average of 5.3% each year. Between 1990 and 2002, the rate increased by 18.1% per year. The contribution played by opioids is also increasing. Between 1999 and 2002 the number of overdose death certificates that mention poisoning by opioid pain killers went up by 91.2%. While the pain killer category showed the greatest increase, death certificates pointing a finger of blame at heroin and cocaine also increased by 12.4% and 22.8% respectively.

In an accompanying 'comment' article, David Joranson and Aaron Gilson of the University of Wisconsin School of Medicine and Public Health Comprehensive Cancer Centre; Pain & Policy Studies Group, of Madison, Wisconsin. They caution against increasing unwarranted fears of using opioid analgesics in pain management, noting that much of the abuse of opioid analgesics is by recreational and street users and individuals with psychiatric conditions rather than pain patients.

Joranson and Gilson also point to the large quantity of opioid analgesics stolen from pharmacies every year, saying that "overdose deaths involving prescription medications do not necessarily mean they were prescribed. It is also crucial to know that most overdose deaths involve several drugs and these data cannot attribute the cause to a particular drug."

In a second commentary, Scott Fishman, Professor of Anesthesiology and Pain Medicine at University of California, Davis concludes that drug abuse and under treated pain are both public health crises, but the solution to one need not undermine the other. "The least we can do is make sure that the casualties of the war on drugs are not suffering patients who legitimately deserve relief," he says.