Opioid poisonings in Washington State Medicaid: trends, dosing, and guidelines.

Background: Opioid poisonings have increased as use of prescription opioid medications have increased. To reduce these poisonings, guidelines for chronic opioid use have been implemented. However, if opioid poisonings occur in individuals who do not have high prescribed doses and who are not chronic opioid users, the current guidelines may need revision.
Objectives: To examine changes in rates of methadone and other opioid poisonings after implementation of the WA State Opioid Guideline in 2007 and to examine the prescription history before poisonings.
Methods: The study sample consisted of individuals who had at least 1 paid claim for an opioid prescription in the Medicaid fee-for-service system between April 2006 and December 2010 and had an emergency department or inpatient hospital claim for an opioid poisoning.
Results: Methadone poisonings occurred at 10 times the rate of other prescription opioid poisonings and increased between 2006 and 2010. Rates of other prescription opioid poisonings appeared to level off after implementation of the WA opioid guideline in 2007. Among individuals with nonmethadone opioid poisonings, only 44% had chronic opioid use, 17% had prescribed doses in the week before the poisoning >120 mg/d morphine-equivalent dose (MED), 28% had doses <50 mg/d MED, and 48% had concurrent sedative prescriptions.
Conclusions: It may be prudent to revise guidelines to address opioid poisonings occurring at relatively low prescribed doses and with acute and intermittent opioid use. Research is needed to establish the best strategies to prevent opioid poisonings.