A new study of overdose deaths in Washington State due to prescription opiate drugs shows that most of these deaths involved methadone, and that these overdoses were much more common among people on Medicaid.

Washington State has a particularly high rate of poisonings with opiate drugs, according to the report from state health officials and the Centers for Disease Control and Prevention (CDC), which is published in the CDC’s weekly bulletin on illness and death. These overdose deaths have been on the rise nationwide since 1999.

To better understand which drugs are involved, as well as whether overdose deaths are more common among poor people, the researchers analyzed all prescription opioid overdose deaths in Washington between 2004 and 2007.

Nearly 60 percent of the 1,668 people who died from prescription opiate overdoses were men, the report indicates. Methadone was the cause of death in 64 percent of these cases, followed by oxycodone (23 percent) and hydrocodone (14 percent).

The biggest percentage of deaths was among middle-aged people 45 to 54 years old, who accounted for 34 percent of overdose deaths. Forty-five percent of people who died were on Medicaid, translating to a 5.7-fold greater risk of prescription opiate overdose death among Medicaid clients.

Studies have shown, noted the authors of the report, that people on Medicaid are twice as likely as those on private insurance to be prescribed opiates. And methadone, long used to treat heroin addiction, is increasingly being prescribed as a cheap painkiller; prescriptions for this purpose rose more than 12-fold between 1997 and 2006.

“These findings highlight the prominence of methadone in prescription opioid-related overdose deaths and indicate that the Medicaid population is at high risk,” the researchers write.

“Efforts to minimize this risk should focus on assessing the patterns of opioid prescribing to Medicaid enrollees and intervening with Medicaid enrollees who appear to be misusing these drugs,” they advise.

They also suggest that other states look at trends in prescription opiate-related deaths, “especially among Medicaid clients.”

SOURCE: Morbidity and Mortality Weekly Report, October 30, 2009.