Illicit drug use is increasing among non-medical users of prescription drugs-Results from population-based surveys 2002-2014.

BACKGROUND: Non-medical use of prescription drugs (NMUPD) is known to be associated with illicit drug use, but less is known about how illicit drug use has changed in NMUPD. We examined (1) the changes in illicit drug use among Finnish non-medical users of prescription drugs during the 2000s and (2) whether the trends of illicit drug use differ by non-medical use of prescription drugs in the general population.

METHODS: Data were derived from population-based (aged 15-69) Drug Surveys conducted in Finland in 2002, 2006, 2010 and 2014. The response rates varied between 63% and 48%. NMUPD during the last year was measured (n=252). Past-year illicit drug use among non-medical users of prescription drugs and the reference population not reporting NMUPD (n=10,967) was compared. Logistic regression was used to estimate the p-values for trends.

RESULTS: Illicit drug use has increased notably among Finnish non-medical users of prescription drugs (from 21% to 70%, p for trend<0.001). This was not explained by the respondents' gender, age, employment status or alcohol use. Among the reference population, illicit drug use also increased statistically significantly, but much more moderately (from 2.5% to 5.4%). The difference between the trends was confirmed by an interaction test (p=0.022).

CONCLUSIONS: NMUPD seems to be increasingly merging with illicit drug use. This indicates an increasing prevalence of polydrug use among non-medical users of prescription drugs, which may bring about more severe harms and worse health outcomes for users and more challenges in regard to treatment.