Non-prescribed use of opioid substitution medication: Patterns and trends in sub-populations of opioid users in Germany (2016)

Background: Non-prescribed use of opioid substitution medication (NPU) appears to represent a relevant source of opioids among European drug users. Little is known about the prevalence of NPU in Germany and possible differences between subgroups of opioid users. The present study examines NPU and other drug use patterns among drug consumption room (DCR) clients, opioid substituted DCR clients, and patients recruited in opioid substitution treatment (OST) practices.
Methods: Cross-sectional data was collected in 2011 from 842 opioid users in 10 DCRs and 12 OST practices across 11 German cities. Structured interviews comprised indicators for socio-demographics, health status, drug use, motives for NPU, and the availability and price of illicit substitution medication. Group differences were examined with one-way ANOVAs, chi-square tests, or t-tests, and factors for NPU were included in a multivariate model. Over-time comparisons were performed with similar data collected in 2008.
Results: Lifetime, 30-day and 24-h NPU prevalence for the total sample was 76.5%, 21.9%, and 9.3%, respectively, with methadone being the most frequently used substance. NPU, poly-drug use and injection drug use were more common among DCR clients, especially among DCR clients not in OST. The three groups featured distinct socio-demographic characteristics, with substituted patients being more socially integrated, while few differences in health parameters emerged. Motives for NPU were mostly related to potential shortcomings of OST, such as insufficient dosages, difficulties with transportation, and lack of access. NPU prevalence was found to be higher than in 2008, while injection rate of substitution medication was similarly low. Main factors associated with NPU were not being in OST, past 24-h use of other drugs, and younger age.
Conclusion: Although diverted methadone or buprenorphine are rarely used as main drugs, NPU is prevalent among opioid users, particularly among DCR clients not in OST. OST reduces NPU if opioid users' needs are met.