TUESDAY, Jan. 19, 2010 (HealthDay News) -- Overdoses from prescription painkillers are increasing in the United States, a new study shows.
Researchers examined pharmacy files on 9,940 adults who took opioids such as oxycodone and hydrocodone for at least three months between 1997 and 2005. The patients, who were insured and members of the Group Health Cooperative in Washington, were prescribed the drugs for chronic pain due to non-cancer causes, including conditions of the back or neck, headaches, jaw pain, pain in the extremities, arthritis and menstrual pain or injuries.
Fifty-one patients overdosed on the drugs; six of the overdoses were fatal, the researchers found.
The risk of overdosing increased with the amount of drug prescribed, according to the study. Those given higher doses had nearly nine times the chance of overdosing as those given lower doses of opioids.
"The rate of overdose was strongly related to dose," said senior study author Michael Von Korff, a senior investigator at the Group Health Research Institute in Seattle. "For patients currently receiving higher-dose regimens, their rate of overdose was almost 2 percent per year, which is a lot."
Patients who were depressed, had a history of substance abuse or who were also taking sedative-hypnotics, such as sleeping pills, had a higher risk of overdosing.
The study is published in the Jan. 19 issue of the Annals of Internal Medicine.
One reason for the greater reliance on opioids is a recognition among physicians that chronic pain is a serious problem, hindering people from working, sleeping and enjoying their lives, Von Korff said.
Use of the drugs also increased after two prominent pain management societies said that pain had been under-medicated because of fears of addiction, said A. Thomas McLellan, deputy director of the White House Office of National Drug Control Policy, who co-authored an editorial accompanying the study.
"That may have been a correct conclusion but, oh baby, did that lead to a dramatic change in practice," McLellan said. "Opioids are now among the most available and the most prescribed class of drugs."
Today, about 3 percent of the U.S. population are long-term users of opioids such as oxycodone, hydrocodone, codeine, morphine and methadone, according to background information in the article. "Our research suggests the rate of use doubled between 1997 and 2005, and probably doubled in the eight or nine years prior to that," Von Korff said.
The greater availability of the drugs has led to an increase in abuse, McLellan noted. Opioids are frequently "diverted," meaning one person gets the prescription and then gives it or sells it to another. A recent study found that less than half of those who died due to accidental overdose had actually received the drugs from a physician.
Yet less was known about the risk of overdosing in patients receiving the drugs from their physicians for pain, Von Korff said.
Among patients in the study, the cause of the overdoses varied. Medical records showed eight people accidentally took too much. Six were suicide attempts, while three had also obtained additional opioids from non-medical sources.
But in most cases, the reason for the overdose was unclear, including whether patients were taking the medications as intended when they overdosed, or if they had accidentally -- or intentionally -- taken more than was prescribed.
Symptoms of people who overdosed were delirium, loss of consciousness, confusion, respiratory problems and falling.
Because of the risks, physicians should closely monitor patients who are on long-term opioid therapy, prescribe as low a dose as possible to control pain and frequently re-evaluate whether the benefit of the drug is worth the risk.
"We need to consider what can be done to maintain the medical benefits of prescribed opiates -- you don't want to reduce appropriate availability -- while recognizing there are public health side effects," McLellan said.
Patient education and patient contracts, in which patients pledge to not share the drugs with others and to only use as necessary, have been shown to help, McLellan said.
"Patients must assume more responsibility for the storage and proper use of these medications, and doctors and dentists must recognize there are public health as well as individual patient implications," McLellan added.
The National Institute on Drug Abuse has more on opioids.