LAS VEGAS—Attempts to reduce opioid overdose risk by limiting prescriptions to less than 100 mg per day may have limited impact, researchers concluded.

Using an insurance claims database, Angela DeVeaugh-Geiss, PhD, of Purdue Pharma L.P., in Stamford, Connecticut, and colleagues identified 3,224 overdose cases among 9.6 million individuals dispensed new opioids. Of the 3,224 cases, 44% had no prescribed opioids in the 30 days preceding the event. This proportion decreased with age, from 59% among those aged 18-24 years to 30% among those aged 50-64 years. At lower doses, most patients had prescriptions for immediate-release (IR) opioids; at higher doses (above 100 mg/day), most had prescriptions for extended-release (ER) opioids.

The trend of the relationship between daily dosage strength and overdose risk changed from a 1.33-fold increase per 50 mg increment to a 1.12 increase after adjusting for IR/ER opioid type. After adjusting for opioid type, patient age, and sedative/hypnotic use, each 50 mg increment in dose was associated with an 8% increased risk of overdose among those aged 18-24, a 6% increased risk for those aged 24-34, a 2% decreased risk among subjects aged 35-44, and an 8% increased risk for patients aged 45-64, the researchers reported.

Compared with the dose category of at least 50 but less than 100 mg, the dose categories of at least 100 mg but less than 150 mg and at least 150 mg but less than 200 mg were associated with a 13% and 19% decreased risk of overdose, respectively, after adjusting for opioid type, patient age, and sedative/hypnotic use.

The findings suggest that comparisons of overdose risk in patients prescribed high vs low opioid doses are confounded by different patient types in the groups, Dr. DeVeaugh-Geiss’ group noted. In adjusted analyses, opioid type, patient age, and sedative/hypnotic use remained significant and strong predictors of overdose risk, according to the investigators. “The high proportion of overdoses without recent prescriptions suggests that many overdoses are from non-prescribed opioids,” they concluded.