Prevalence of Benzodiazepine Prescription Prior to Overdose Deaths Compared to Toxicological Findings

Background:

Diazepam and oxazepam are the most commonly prescribed benzodiazepines in Norway. Furthermore, the most prevalent benzodiazepines in overdose deaths are detected in 65% of the cases. To effectively implement preventive measures against overdose deaths, it is crucial to determine whether these benzodiazepines were obtained through legitimate prescriptions or not.

Methods:

The study utilized data from the Norwegian Cause of Death Registry (NCoDR), the Norwegian Prescribed Drug Registry (NorPD), and forensic toxicological results obtained from forensic autopsies spanning the period from 2004 to 2021. The study specifically examined the dispensation of diazepam, oxazepam, clonazepam and alprazolam within 12 and two months preceding death in cases of overdose where those substances were detected during autopsy. More advanced statistical methods and time trend studies will be performed before the conference.

Results:

A total of 3,765 overdose deaths were analysed. Clonazepam was detected in 1,306 cases, whereas 17% had received a prescription within the past 12 months prior to death and 14% within the past two months. For diazepam (n = 1198), the proportion were 54% within the past 12 months and 45% within the past two months. For alprazolam (n = 474), the proportion were 25% within the past 12 months and 21% within the past two months, while for oxazepam (n = 206), the proportion were 75% and 69%, respectively. The proportion who had received a prescription was higher among women compared to men. In addition, an age difference was observed for diseased with detected benzodiazepines. It was highest for diazepam, where 30% below 40 years and 58% over 40 years had a prescription. Concomitant use of at least one illicit drug was also studied, and the proportion of prescriptions was lower among those who also used illicit drugs. 

Conclusion:

The study found that the proportion of overdose deaths with prior dispensation of diazepam, oxazepam, clonazepam and alprazolam was highest for oxazepam, with approx. 75% of cases. Additionally, half of the deaths with diazepam also had a prescription history, while in cases were clonazepam and alprazolam were detected, 83% and 75% did not have a prescription. This means that for the most prevalent benzodiazepine, clonazepam, 1,078 overdose deaths were without prescription. Prescription drug use was associated with higher age, the absence of concomitant illicit drug use, and being female. Conversely, the absence of prescription drug use was associated with being male, using illicit drugs, and being younger.