A cross-national analysis of the association between years of implementation of opioid substitution treatments and drug-related deaths in Europe from 1995 to 2013.

Data at the individual-level provide evidence that opioid substitution treatment (OST) programs protect against mortality for opioid dependent populations. Prior research has not examined the merits of national implementation of opioid substitution programs for reducing mortality at the country-level. This study elucidates longitudinal associations between country-level implementation of opioid substitution treatment programs on mortality rates of drug related deaths (DRD) from 1995 to 2013 in 30 European nations. Cases of DRD were measured using National Definitions for each country from official sources of data. Preliminary analysis of dispersion of cases of DRD using means and variances justified use of the negative binomial regression model with a population offset. Year and country-level fixed effects negative binomial regression models investigated the association between years of implementation of methadone maintenance therapy (MMT), OST in prison, and high dose buprenorphine treatment (HDBT) implementation and mortality rates from drug related deaths after adjusting for unemployment rates, heroin seizures and per capita expenditures on health. Beta coefficients were converted to Incidence Rate Ratios (IRR) and standard errors bootstrapped using non-parametric methods to adjust for bias (SDbs). The mean mortality rate of DRD was 1.81 from 1995 to 2013. In adjusted models, each additional year of MMT (IRR = .61, SD = .04, p < .001; SDbs = .08, p < .001), prison OST (IRR = .90, SD = .01, p < .001; SDbs = .02, p < .001), and HDBT (IRR = .09, SD = .02, p < .001; SDbs = .02, p < .01) was significantly associated with lower rates of DRDs after adjusting for country and year fixed effects. Implementation of OST programs in the general population and in prison settings may have protected against mortality from drug use at the country-level in Europe from 1995 to 2013.