Mortality risk from opioid overdose has previously been measured in terms of thresholds of risk. Four scientists linked to the UNC Gillings School of Global Public Health and UNC Injury Prevention Research Center are co-authors on a new cohort study finding that dose-dependent opioid overdose risk among patients does not show evidence of a distinct risk threshold.
Their article, titled “Cohort Study of the Impact of High-dose Opioid Analgesics on Overdose Mortality,” was published online Sept. 1 by Pain Medicine.
Nabarun Dasgupta, PhD, is a 2013 alumnus of the Department of Epidemiology at the Gillings School, and is currently a Senior Researcher at UNC IPRC. Steve Marshall, PhD, is the Director of UNC IPRC, and a professor in the Department of Epidemiology, where Michele Jonsson-Funk, PhD, research assistant professor, is also faculty. Kurt Ribisl, PhD, is a professor of health behavior at the School and a member of the Lineberger Comprehensive Cancer Center at UNC.
The researchers used Poisson regression models to quantify dose-dependent overdose mortality across a large spectrum of clinically common doses and examined the contributions of benzodiazepines and extended-release opioid formulations to mortality.
Using one year of name-linked mortality data from a controlled substances prescription-monitoring program in North Carolina, the team discerned that opioid analgesics were dispensed to 22.8 percent of N.C. residents. There were 629 overdose deaths during the study year, half of which had an opioid analgesic prescription active on the day of death.
The models found that mortality rates increased gradually as the average daily milligrams of morphine equivalents rose.
Additionally, 80 percent of opioid analgesic patients also received benzodiazepines, and rates of overdose death were 10 times higher among those co-dispensed both opioid analgesics and benzodiazepines.
This cohort study underscores the urgent need to disseminate updated guidance to the medical community about the risk associated with co-prescribing classes of medicines. This will facilitate a better balance between pain relief and overdose risk for patients using opioids.