Prescription high-risk polysubstance use among opioid maintenance treatment patients.

BACKGROUND: Among individuals receiving buprenorphine or methadone as opioid maintenance treatment (OMT), concomitant use of other central nervous system depressants, including prescription drugs, can increase risk of overdose. We aimed to 1) determine the prevalence of use of high-risk prescription drugs (opioid analgesics, benzodiazepines, benzodiazepine-related drugs, and gabapentinoids) among OMT patients, 2) calculate its associations with different mental health and pain-related diagnoses, and 3) compare prevalence of concomitant use with the general population. METHODS: A national sample comprising all individuals filling at least one prescription of OMT drugs in Norway in 2019 was formed. Healthcare registry data were linked to investigate high-risk prescription drug use and different diagnoses. We calculated one-year prevalence of use, amount dispensed in defined daily doses (DDDs), and the number of prescribers for the different high-risk prescription drugs. Logistic regression was used to determine associations (adjusted odds ratios; aOR, 95% confidence intervals (CIs)) between diagnoses and use. Prevalence of use was calculated both in the OMT patient sample and the general population. RESULTS: Among the OMT patient sample (n=7,299), 47.6% (n=3,476) filled prescriptions for benzodiazepines. For each high-risk prescription drug group, there was a median of 1-2 prescribers. Musculoskeletal diagnoses were the strongest factor for concomitant high-risk prescription drug use for both males (aOR 3.23, CI: 2.72-3.85) and females (aOR 3.07, CI: 2.42- 3.90). The 1-year prevalence of benzodiazepine use was 11.4 times higher for males and 7.1 times higher for females in OMT than the general population. The amount in DDDs was higher for every drug for OMT patients than the general population, particularly for benzodiazepines. CONCLUSIONS: OMT patients frequently filled prescriptions for high-risk drugs, and in higher dosages than the general population. However, we found little evidence of 'doctor shopping.' Given that these prescription drugs carry overdose risk, particularly when combined with OMT drugs, our findings emphasize the continued need for education and caution to both prescribers and patients on their concomitant use with OMT.