Higher opioid dose linked to overdose risk in people with chronic pain
20 January 2010
The use of medically prescribed opioids such as Oxycontin and Vicodin for chronic pain has increased in recent years in the USA. More than eight million American adults - around 3 per cent of the adult population - are estimated to be using opioids long-term. The Centers for Disease Control and Prevention recently reported that nearly 14 000 US deaths involved prescription opioids in 2006, more than triple the number in 1999.
In a study published in the 'Annals of Internal Medicine', researchers led by Dr Michael Von Korff, a senior investigator at the Group Health Research Institute in Seattle, studied nearly 10 000 patients who received multiple opioid prescriptions for common chronic pain conditions such as back pain and osteoarthritis (and excluding cancer-related pain).
Most of the overdoses occurred among patients receiving low to medium doses, as prescriptions at those levels were much more common. However, the researchers found that patients who received higher opioid doses were nine times more likely to overdose than were those receiving low doses.
"Some studies have indicated that fatal opioid overdoses occur most often among people abusing prescription drugs or obtaining them from non-medical sources," Dr Von Korff said. "But our results suggest that many overdoses may occur among people using prescribed opioids."
Dr Von Korff believes that doctors should carefully evaluate and monitor patients using opioids long-term.
"Fatal overdose may be only the tip of the iceberg," said Dr Von Korff. "For every fatal overdose in our study, seven non-fatal overdoses occurred, and most of the non-fatal overdoses were medically serious."
The findings were described as "concerning" by Dr Kate Dunn, a Wellcome Trust Research Career Development Fellow at Keele University, the study's lead author.
Further study is required to determine all the potential contributing factors to the overdoses, such as accidental or intentional ingestion of more opioid than prescribed, suicide attempts, or opioids obtained from non-medical sources. Depression tends to be common among people with chronic pain using opioids long-term. According to Dr Dunn, suicide attempts and drug abuse were sometimes mentioned as factors, but were noted in only a minority of the overdoses in this study.
Image: Artwork - pain and disturbance. Credit: Chris Nurse, Wellcome Images
Reference
Dunn, KM et al. Opioid prescriptions for chronic pain and overdose: a cohort study. Ann Intern Med. 2010;152:85-92.
